Final PSPCL report part 1

Final Report

Submitted to

Punjab State Power Corporation Ltd., Patiala

on

Consultancy Works on Study of Induction Billet

Heaters and Induction Surface Hardening Machines

(Work Order No. 5 dt. 29.05.2012 & No. 3 dt. 29.04.2013)

Report No: ERED/EA/128/2012-2013

July 2013

ENERGY EFFICIENCY & RENEWABLE ENERGY DIVISION

Central Power Research Institute, Prof. Sir C.V. Raman Road, P.B. No 8066,

Sadashivanagar, Bangalore – 560 080 E-mail: [email protected]

Web-site: http://www.cpri.in

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EXECUTIVE SUMMARY

Punjab State Power Corporation Ltd., (PSPCL) is distributing power to industries in

Punjab state. PSPCL is providing the power supply for industries at 11 kV or 66 kV

depending on the contract demand. Generally up to 2500 kVA contract demand PSPCL

will provide power supply at 11 kV and above 2500 kVA, the grid supply power will be of

66 kV.

PSPCL declared induction furnaces, induction billet heaters, induction surface

hardening machines and arc furnaces as power intensive industries.

In order to define the criteria for declaring induction billet heaters as Power intensive

industries, 28 numbers of Billet heating induction furnaces of 10 kW to 4000 kW and 10

numbers of induction surface hardening machines are studied in the vicinity of

Ludhiana, Jalandhar, Mohali & Khanna Circles.

At the same time, to study and compare the behavior and nature of Billet heating

induction furnace with induction melting furnaces and arc furnaces, five numbers of

induction melting furnaces of different capacities from 300 kg output to 6000 kg output

are also studied. One arc furnace was also studied to know the behavior of arc furnace.

The induction billet heater works on the principle of transformer. Due to mutual

inductance, the magnetic field produced surrounding the coil induces an equal and

opposing electric current in the billet and billet will heated up due to the resistance to the

flow of the induced current i.e., eddy current. The rate of heating of the billet is

dependent on the frequency of the induced current, the intensity of the current density,

the specific heat of the material, the magnetic permeability of the material, and the

resistance of the material to the flow of current. Induction heat treating involves heating

a billet from room temperature to a higher temperature, as is required for different

applications like induction tempering or induction austenitizing. The heating rates and

efficiencies depend upon the physical properties of the billets (chemical composition of

metal). These properties are temperature dependent, and the specific heat, magnetic

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permeability, and resistivity of metals change with temperature. The resistivity of steel at

room temperature is about 18.8 µΩ-cm which about nearly 11 times that of copper (1.7

µΩ-cm). As the temperature increases the resistivity of steel increases drastically

compared to copper. The steel exhibit a resistivity of about 121.9 µΩ-cm at a

temperature of 980 oC and that of copper resistivity is 9.4 µΩ-cm.

The magnetic permeability of steel is high at room temperature, but when the steel

temperature crosses the Curie temperature (just above 780 °C), steels become

nonmagnetic with the effect that the permeability becomes the same as air. As the steel

is heated by induction heating from room temperature to higher temperature, the

alternating magnetic flux field causes the magnetic dipoles of the material to oscillate as

the magnetic poles change their polar orientation every cycle. This oscillation is called

hysteresis, and a minor amount of heat is produced due to the friction produced when

the dipoles oscillate. When steels are heated above Curie temperature they become

nonmagnetic, and hysteresis ceases. Because the steel is nonmagnetic, no reversal of

dipoles can occur. Therefore only eddy current will help in heating

The billet heaters, surface hardening machines and induction melting furnaces work on

the same principle of AC variable high frequency power supply. In both cases, the grid

power frequency supply (50 Hz) is converted to DC by rectifiers and inverted back to

varying frequency AC source. The heating effect depends on the frequency i.e., at high

frequency the heating or melting is fast.

The power quality parameters are almost similar in both induction billet heaters / surface

hardening machines as well as induction furnaces and there is no difference in power

quality parameters like current & voltage harmonics, voltage flicker and voltage dip.

The sudden change in non-linear load due to billet heating and melting of metals cause

dip in voltage which is again depends on network short circuit capacity. During

measurement the non-linear load of 600 kVA was in service. At Kay Jay Forging, during

measurement at 11 kV incomer side, the current is increased by 12.21 % which had

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reduced the voltage by about 1.265 % which is very high. The average voltage change

during the entire measurement is 0.65 %.

At Nidhi Furnace, during the measurement at main incomer on 11 kV side, the current is

increased by about 603.5 %, the voltage drop is 2.91 % which is on higher side. This

higher voltage is may be due to the short circuit MVA is less (11 kV incomer for the

contract demand of 2500 kVA).

During measurement the non-linear load of 40 kVA was in service at Presto Forging, the

current at main incomer on 11 kV side is increased by 69.23 %, the voltage dip is 0.026

% which is on lower side compared Kay Jay Forging.

The average voltage dip is measured in the range of

• Billet heaters: 0.03 to 0.65 %

• Hardening machines: 0.09 to 0.47 %

• Induction furnaces: 0.09 to 2.05 % and

• Arc Furnace : 0.70 %

The average voltage drop (curve fit value from graph) at 400 kVA non-linear load (billet

heater load) is about 0.30 %.

The total voltage drop due to six industries in one 11 kV feeder is 6 x 0.40 % (average

value from curve fit) = 2.4 %. The estimated voltage drop for 11 kV feeder for average

distance of 6 km based on KVA-KM basis is 4.68 % (data provided by PSPCL)

The total voltage drop due to non-linear load of average six industries (having a non-

linear load of 500 kVA each) and the voltage drop due to resistance of conductor is (2.4

+ 4.68 ) = 7.08 %. Considering the diversity factor of 70 % for industrial load, the voltage

drop will be 4.96 %. This voltage drop is not in the control of utility and is due to

industrial power pollution and load. As per IE rules 1956 rule number 54, the voltage dip

must be maintained at -9.0 %. Therefore the utility will have a margin of only about 4.04

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% on negative side for maintaining the voltage within permissible limit of IE rule 54

which is very less & critical.

At Varun steel industries, during the measurement at 66 kV incomer side, the current is

increased by 176.5 %, the voltage drop is 0.27 %.

At Happy Forging (billet heaters), during the measurement at 66 kV incomer side, the

current is increased by 1.13 %, the voltage drop is 0.53 %.

At Happy Forging (induction hardening machines), during the measurement at 66 kV

incomer side, the current is increased by 9.17 %, the voltage drop is 0.09 % which is on

lower side compared to Kay Jay Forging.

The non-linear loads like induction billet heaters, surface hardening machines and

induction furnaces, generate inter harmonics in the system. The inter harmonics are not

the integer value of the harmonics. These inter harmonics create the voltage flicker in

the system. The integer harmonics can be suppressed by installing the harmonic filters

but it is very difficult to suppress the inter harmonics which cause voltage flicker in the

system. These voltage flickers cause inconvenience to the human eyes. The flicker

limits as per IEEE Standard 1453 – 2004 (refer Figure 7), “Measurement and limits of

Voltage Fluctuations and Associated Light Flicker on AC Power Systems”.

IEC flicker meter’s output is simple: if the output is greater than 1.0, the flicker is

generally irritable to humans (as per IEC 61000-3-7); if less than 1.0, it is not. These

results have been successfully validated with many years of real world testing in several

countries. The flicker meter’s main output is in a unit called PST, meaning, “Perception

of light flicker in the short term.”

The average harmonic current is measured in the range of

• Billet heaters: 1.0 to 10.67 A

• Hardening machines: 0.80 to 13.74 A

• Induction furnaces: 2.37 to 18.86 A and

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• Arc Furnace : 6.36 A

The harmonic current increases with the increase in non-linear load i.e., capacity of

induction billet heater / hardening machines. For all induction billet heaters, hardening

machines and induction furnaces, the harmonic current is almost same but in case of

Nidhi Furnace the harmonic current is high because the contract demand is 2500

(during study only one furnace of 4.0 t capacity furnace was in service) & is connected

with 11 kV system. Therefore, to compensate the harmonic current at PCC, higher short

circuit level (i.e., higher impedance level of utility grid) is required to suppress the

harmonic currents.

Due to non-linear loading, the current waveform is distorted. This non-linear loading

distorts the voltage waveform at billet heater. The non-linear loading of billet heaters

distorts the voltage waveform and pollute power quality of the utility grid.

The presence of harmonics in the system reduces the capacity of distribution capacity

of utilities i.e., transformers, overhead lines, cables, circuit breakers, etc.

The approximate capacity loss due to harmonics present in industries at PCC are

computed. The average distribution capacity reduction is computed as:



• Induction furnaces: 0.10 to 2.27 %


The capacity loss increases with the increase in non-linear load i.e., capacity of

induction billet heater / hardening machines. For all induction billet heaters, hardening

machines and induction furnaces, the capacity loss is almost same but in case of Nidhi

Furnace the capacity loss is high because the contract demand is 2500 (during study

only one furnace of 4.0 t capacity furnace was in service) & is connected with 11 kV

system. But on the other hand at Varun Furnace the capacity loss is 0.1 % & is less

because the incoming power supply voltage is 66 kV. During the measurements, at both

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these industries, only one induction furnace of 4.0 t capacity was in service. Similarly at

Happy forging where surface hardening machines are installed and incoming voltage is

66 kV, the distribution capacity loss is very less of about 0.03 %.

As the harmonic current increases the true maximum demand will increase but the

static energy meters will record only RMS value of maximum demand. The average

excess demand is computed as:

• Billet heaters: 19.7 to 597.8 kVA (4.10 – 24.84 %)

• Hardening machines: 40.0 to 185.0 kVA (7.41 – 30.0 %)

• Induction furnaces: 59.2 to 275.6 kVA (6.59 – 20.5 %)

• Arc Furnace: 654.9 kVA (4.68 %)

It can be seen from the Figures that the excess demand increases with the increase in

non-linear load i.e., capacity of induction billet heater / hardening machines. For all

induction billet heaters, hardening machines and induction furnaces, the capacity loss is

almost same.

Since the concern is with respect to power or demand not with energy parameters,

therefore, the demand factor is essential.

The demand factor is varying in the range of:

• Billet heaters: 8.34 to 100.57 %; At few industries like Nicks India, Turbo tools,

Sunitha Bicycle & Presto Forging demand factor is less may be due to

lower rating of billet heaters are used.

• Hardening machines: 21.09 to 91.59 %; At Happy forging the demand factor is

less may be due to high contact demand.


• Arc Furnace: 70.05 to 79.84 %

The demand factor for all billet heaters, induction hardening machines, induction

furnace and arc furnaces is almost same. And there is no significant difference in

demand factor for all these machines.

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The non linear load will not exhibit true power factor. The true power factor of non linear

load (where harmonic currents are present) consists of two parameters i.e.,

dispacement factor and distortion factor.

The distortion factor is inversly proportional to current THD. Therefore, as the current

THD increses, the true power factor will become less. For a non linear load even if their

displacement factor is good but the true power factor will be low. Therefore, all these

induction billet heaters, surface hardening machines and induction furnaces exhibit

higher current THD which cause lower true power factor.

The presence of harmonics in the system i.e., current harmonics from the industry leads

to voltage harmonics and voltage harmonics increases the iron losses (hysteresis loss α

frequency & eddy current losses α square of frequency) of utility power transformers.

The average energy loss is computed as:

• Billet heaters: 0.30 to 58.09 kWh/month

• Hardening machines: 0.73 to 48.43 kWh/month

• Induction furnaces: 5.4 to 221.7 kWh/month

• Arc Furnace: 72.5 kWh/month

The energy loss in utility power transformer increases with the increase in non-linear

load i.e., capacity of induction billet heater / hardening machines. But the energy loss

due to Nidhi furnace is very high because the harmonic current is high and the main

incoming voltage is 11 kV.

In most of the induction billet heaters, hardening machines, induction furnaces and arc

furnaces, the impact of energy loss in utility power transformer is almost same but

depends on the utility voltage level of power supply at PCC.

In the billet heaters the energy is used to only heat the billets of smaller size and there

is no change in state of material. But in case of induction melting furnaces, while

heating the iron is converted from solid to liquid i.e., state change. In induction furnace,

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the melting temperature is higher in the range of 1500 – 1600 oC compared to billet

heaters in the range of 1200 – 1250 oC & surface hardening machines in the range of

950 – 1150 oC. At higher temperature, the steel resistivity will be very high which draws

higher current and hence the SEC will be high. Thus the energy used at induction

furnace is higher compared to billet heaters and surface hardening machines.

The average Specific Energy Consumption (SEC) for different machines is:

• Billet heaters: 0.24 to 0.83 kWh/kg of steel; but at presto forging the SEC is in the

range of 0.013 to 0.026 kWh/piece of tools and is very less because the heating

will takes place at hardly 25 to 35 mm at front portion of tools which is forged only

front portion.

• Hardening machines: 0.126 to 18.86 kWh/piece of surface hardening and is

varying widely may be due to varying in temperature and different surface area.

• Induction furnaces: 0.74 to 0.902 kWh/kg of steel and is slightly high compared to

billet heater may be because of higher temperature requirement & change of

state of material from solid to liquid.

• Arc Furnaces: 0.455 to 0.669 kWh/kg of steel and is comparable with both billet

heaters and induction furnaces.

The SEC increases with the increase in non-linear load i.e., capacity of induction

billet heater / hardening machines whereas in case of induction furnaces as the capacity

of induction furnace increases the SEC decreases.

Therefore, it is very difficult to differentiate billet heater and induction melting furnace as

far as power quality and power supply parameters are concerned but SEC will be less

for billet heaters compared to induction melting furnace. But the concern is with power

or demand and not with energy consumption.

Therefore, the utility must provide higher level of short circuit MVA to absorb the power

quality pollutants created by the industry which is having a larger capacity of non-liner

loads. The utilities to overcome these issues of power quality and voltage fluctuations in

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the grid, they are declaring industries whose loading pattern is non-linear as power

intensive industries.

"The Billet heaters and surface hardening machines can be considered as power

intensive industry because already induction furnaces are considered as power

intensive industries by PSPCL. The working principle and operational behavior

with respect to power supply and power quality parameters for billet heaters,

surface hardening machines & induction furnaces are same. The impact of power

quality parameters like voltage dip, voltage flickers, voltage & current waveform

distortions, harmonics, capacity loss of utility distribution system, demand

factor, energy loss in distribution system, etc; have same effect. Only the specific

energy consumption for induction furnaces is slightly higher compared to billet

heaters due to the change of state of material from solid to liquid & higher degree

of melting temperature”.

The non-linear load is the load where the current is not proportional to voltage

and current waveform is distorted which distorts the voltage waveform. The

induction billet heaters, induction surface hardening machines, induction

furnaces can be considered as non-linear load because these equipments

produce heavily distorted current waveforms that cause the distortion of voltage

waveform which will also create voltage dips & voltage flicker in the system.

CONTENTS

Page Nos.

EXECUTIVE SUMMARY i

1.0 INTRODUCTION 1

1.1 Induction Billet Heaters

1.2 Induction Surface Hardening Machines

1.3 Induction melting furnaces

1.4 Arc Furnace

1.5 Scope of Work

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2.0 EXPERIMENTAL WORK 8

3.0 POWER INTENSIVE INDUSTRY 9

3.1 Principle of induction heating

3.2 Voltage variation

3.3 Voltage Flicker

3.4 Harmonic current

3.5 Current & Voltage Waveforms

3.6 Capacity reduction of utility distribution system

3.7 Excess Demand

3.8 Power Factor

3.9 Demand Factor

3.10 Energy loss in utility distribution system

3.11 Specific Energy Consumption

3.12 Energy intensive factor

3.13 Overall Appraisal

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4.0 FIELD MEASUREMENTS, OBSERVATIONS, STUDY RESULTS

AND DISCUSSIONS 48

4.1 Billet Heaters

4.1.1 Kay Jay Forging

4.1.2 Happy Forging

4.1.3 Emson Tools

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4.1.4 Sherpur Forging

4.1.5 Turbo Tools

4.1.6 Sunitha Sony Bicycle

4.1.7 Eastman Cast & Forge

4.1.8 Ismeet Forging

4.1.9 Leela Forging

4.1.10 Nicks India Tools

4.1.11 JVR Forging

4.1.12 Perfect Forging

4.1.13 PS Industries

4.1.14 Global Export

4.1.15 Jai Parvati Forging

4.1.16 Samrat Forging

4.2 Induction Surface Hardening Machines:

4.2.1 Presto Forging

4.2.2 Nakul Gupta Automobile Parts

4.2.3 Rama Steel

4.2.4 Happy Forging (Hardening)

4.2.5 GNA Enterprises

4.2.6 GNA Udyog Ltd.

4.3 Induction melting furnaces:

4.3.1 Garg Furnaces

4.3.2 Raj Furnaces

4.3.3 Basant Metal Works

4.3.4 Nidhi Steel Industries

4.3.5 Varun Steel Casting

4.4 Arc furnace: Upper India Steel Industries

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5.0 CONCLUSIONS 96

Annexure I - Figures 99

Annexure II – ACSR conductor rating 471

Annexure III – Minutes signed during measurements at site 472

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1.0 INTRODUCTION

This section introduces the Induction Billet heaters, Induction melting furnaces and Arc

furnaces, scope of the work and power measurement system.


Induction heating is mainly because of two kinds of heat generation i.e., through

hysteresis loss and eddy current loss.

The induction billet heater works on the principle of transformer. Alternating current is

fed to induction coil which acts as transformer primary and the billet to be heated is

placed inside the coil acts as secondary of transformer. Due to mutual inductance The

magnetic field produced surrounding the coil induces an equal and opposing electric

current in the billet and billet will heated up due to the resistance to the flow of the

induced current i.e., eddy current. The rate of heating of the billet is dependent on the

frequency of the induced current, the intensity of the current density, the specific heat of

the material, the magnetic permeability of the material, and the resistance of the

material to the flow of current. Induction heat treating involves heating a billet from room

temperature to a higher temperature, as is required for different applications like

induction tempering or induction austenitizing. The heating rates and efficiencies

depend upon the physical properties of the billets. These properties are temperature

dependent, and the specific heat, magnetic permeability, and resistivity of metals

change with temperature. Figure 1 shows the variation of specific heat (ability to absorb

heat) with temperature for various materials (© 2001 ASM International, Practical

Induction Heat Treating (#06098G)) Steel has the ability to absorb more heat as

temperature increases. This means that more energy is required to heat steel when it is

hot compared to when it is cold. The resistivity of steel at room temperature is about

18.8 µΩ-cm which about nearly 10 times that of copper (1.7 µΩ-cm). As the temperature

increases the resistivity of steel increases drastically compared to copper. The steel

exhibit a resistivity of about 121.9 µΩ-cm at a temperature of 980 oC and that of copper

resistivity is 9.4 µΩ-cm.

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Figure 2 shows the curie temperature of carbon steel (ABCD path). The magnetic

permeability of steel is high at room temperature, but when the steel temperature

crosses the Curie temperature (just above 780 °C), steels become nonmagnetic with

the effect that the permeability becomes the same as air.

Hysteresis losses occur only in magnetic materials such as steel. As the steel is heated

by induction heating from room temperature to higher temperature, the alternating

magnetic flux field causes the magnetic dipoles of the material to oscillate as the

magnetic poles change their polar orientation every cycle. This oscillation is called

hysteresis, and a minor amount of heat is produced due to the friction produced when

the dipoles oscillate. When steels are heated above Curie temperature they become

Figure 1: Variation of Specific heat for different materials

with temperature.

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nonmagnetic, and hysteresis ceases. Because the steel is nonmagnetic, no reversal of

dipoles can occur.

It can be seen from the Figure 1 that as the temperature of steel increases the specific

energy consumption increases exponentially till curie temperature (780 oC) may be due

to both eddy current & hysteresis loss contribute. After the curie temperature the

specific energy consumption linearly increases with temperature may be due to only

eddy current loss takes place and resistivity of steel increases drastically.

In the billet heaters, the temperature of steel will be increased to about 1200 to 1250 oC

depending on the type of steel with carbon percentage and job. But in these billet

heaters, the temperature of steel will be higher than the curie temperature but the phase

of material (steel) will be in solid state only and there is no change in phase whereas in

induction furnace the phase of material will change from solid to liquid which may take

higher specific energy consumption.

Figure 2: Curie temperature of carbon steel.

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The billets are heated in the induction furnace and forge to the required shape. The

billet temperature will be maintained generally in the range of 1200 to 1250 oC. Since

these furnaces require high frequency power supply at induction coil. The grid power

supply of power frequency of 50 Hz is converted to DC by using rectifier bridges and

again inverted back to AC with varying high frequency power supply. While converting

power supply from power frequency to high frequency AC supply, harmonics are

generated and pollute the power supply of grid. This billet heaters distorts the current

waveform and that distorts the voltage waveforms of incoming power supply. This

distorted waveforms and harmonics cause voltage flicker and sudden voltage dips in the

grid supply.

Induction billet heaters are used for various applications like heating the steel rod to red

hot for forging, surface hardening of automobile parts, surface hardening of tools, etc.

The starting characteristic billet heater of 300 kVA at Samrat forging is studied. The 300

kVA billet heater is started from room temperature and is maintained to about 1200 oC.

Figure 3 gives the variation of voltage and current with time and Figure 4 shows the

variation of power and current THD with time. The observations from the study are as

follows:

a) The time taken for attaining the temperature of about 1200 oC from room

temperature is 3 minutes: 45 seconds.

b) The current is gradually increased from zero to 409.5 A and the average current

ramp is 1.82 A/sec.

c) When the current increases the voltage at billet heater decreases from 406.5 V

to 395.9 V. The voltage drop is 10.6 V (2.61 %)

d) The power is increased from zero to 268.34 kW and the average ramp time is

1.19 kW/sec.

e) The current THD is suddenly increased from zero to 49.77 % for about 15 sec,

drops down to 29.63 %. Then the current THD is almost steady with slight

decrease to about 28.27 %.

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f) With this we can conclude that increase in billet heater temperature will have less

influence on the current THD, but the current & power increases gradually

whereas the voltage decreases.

Figure 3: Variation voltage & current at 300 kVA billet heater at Samrat Forging

Figure 4: Variation Power & current THD at 300 kVA billet heater at Samrat Forging

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Surface hardening induction machines are similar to the induction billet heaters. In

induction surface hardening machines, the power frequency is converted to DC,

inverted with high frequency AC power source and fed to induction coil. In surface

hardening machines only outer surface of the object will be heated to particular

temperature in the range of 950 to 1050 oC depending on the type of job (data provided

by PSPCL). The job will be quenched by injecting water on the job for tempering. This

surface hardening can be done for the entire portion of the job or only certain area be

heated depending on the requirement. In these machines also the object temperature

will be above the curie temperature of material.

The basic purpose of induction heating is that the eddy currents are produced on the

outer surface of the object which is referred to as “skin effect” heating. Because almost

all of the heat is produced at the surface, the eddy currents flowing in a cylindrical object

will be most intense at the outer surface, while the currents at the center are negligible.

The depth of heating depends on the frequency of the magnetic field, the electrical

resistivity, and the relative magnetic permeability of the object. The skin heating effect

(reference depth) is defined as the depth at which approximately 86 % of the heating

due to resistance of the current flow occurs. The skin effect depth on the surface of the

object decrease with increase in frequency and increase with increase in temperature.

1.3 Induction Melting Furnace

The induction melting furnace also works on the same principle of induction heating. But

in induction melting furnace, the steel scrap is melted in furnace and the temperature of

furnace will be in the range of 1500 to 1600 oC. In induction furnace, the material (steel)

temperature will be above curie temperature and the phase of the material will change

from stolid to liquid which will draw more energy to melt the steel. Therefore, the specific

energy consumption for Induction melting furnace will be higher compared to billet

heaters. The process time will vary from 1½ hours to 3 hours. In induction melting

furnaces the chemicals can be added depending on the type of steel. In these furnaces

also harmonics are generated while converting 50 Hz grid power supply to high

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frequency AC power supply that cause voltage flicker and pollute the grid power supply.

In these induction furnaces the grid power supply of power frequency of 50 Hz is converted to

DC by using rectifier bridges and again inverted back to AC with varying high frequency power

supply. While converting power supply from power frequency to high frequency AC supply,

harmonics are generated and pollute the power supply of grid. These induction furnaces

generate distorted current waveform that distorts the voltage waveforms of incoming power

supply. This distorted waveforms and harmonics cause voltage flicker and sudden voltage dips

in the grid supply.

1.4 Arc furnaces & Laddle furnaces

In arc furnaces, the electrical supply is fed between two electric rods and arc is created

between two electrodes, this arc heats the metal. The temperature of arc furnace also

vary in the range of 1500 to 1600 oC. Generally there are two types of arc furnaces i.e.,

DC arc furnaces where AC is converted to DC through rectifiers and fed to electric rods

and AC arc furnaces where directly AC is fed to Electric rods to create arc. Both of

these arc furnaces induces harmonics in the grid power supply.

Therefore, the principle used in induction furnaces, induction billet heaters and

induction surface hardening machines is same but the frequency of machines will

vary depending on the material. Since the temperature requirement for induction

furnace is higher in the range of 1500 to 1600 o C where the material phase will

change from solid to liquid and specific energy consumption will be higher

compared to billet heaters (temperature in the range of 1200 – 1250 oC) / surface

hardening machines (temperature in the range of 950 – 1150 oC). The power

quality parameters and impact of power quality parameters on the utility grid at

point of common coupling (PCC) is same but the intensity of impact will vary

depending on the short circuit level of the grid at PCC (i.e., impact at 11 kV

system will be higher due to lower short circuit level compared to 66 kV system).

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1.5 Scope of work

The scope of work involves:

a) Measurement of power supply parameters like voltage, current, harmonics,

power factor, maximum demand, active power in kW and reactive power in kVAR

for Billet heaters, Induction surface hardening machines, Induction furnaces and

Arc furnaces.

b) Measurement of current & voltage harmonics at individual furnaces and at main

incomer.

c) Logging of energy consumption at induction and arc furnaces at the point where

power is tapped from PSPCL grid power supply for one cycle.

d) Collect the information on production during the power measurement for

induction furnaces.

e) Generally in induction and arc furnaces, the electricity is directly a part of the

process (direct electricity is either passed or induced in raw material) and

variation in production will have great impact on the grid conditions. This will

pollute the grid and to maintain the grid stability, the utility may have to provide

sufficient distribution capacity and short circuit level of the grid power supply.

f) Analysis of the power supply parameters and computing specific energy

consumption for both furnaces.

g) Computation of SEC.

h) Identifying the criteria for declaring power intensive industry.

2.0 EXPERIMENTAL WORK

The field measurements for the first phase were carried out between 04.08.2012 to

07.08.2012. and for the second phase from 03.06.2013 to 08.06.2013. The field work

consists of:

Measurement of voltage, current, power factor and power at 25 billet heaters, 8

induction surface hardening machines, 5 induction melting furnaces and one Arc

furnace.

Measurement of individual voltage & current harmonics upto 50th order at all the

points.

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Measurement of voltage & current total harmonic distortion (THD) at all the

points.

Measurement of voltage profile at main incomer as well as at individual furnaces.

Collection of production data like number of pieces and output in weight.

Collection of monthly energy consumption & demand data for all industries.

3.0 POWER INTENSIVE INDUSTRY

Utilities have to provide the power supply to the customers according to Indian

Electricity (IE) Rules. While providing the power supply connection to individual

customer, the utility will decide the voltage level depending on the connected load &

contract demand. The utility must provide the required short circuit MVA for the

customers to maintain the power supply parameters within the prescribed limit of IE

Rules and Electricity Act 2003. The Distribution Licensee shall control the harmonics

level at the point of supply in accordance with that prescribed by the IEEE STD 519-

1992, namely “IEEE Recommended Practices and Requirements for Harmonic Control

in Electrical Power Systems” i.e., voltage harmonic needs to be maintained at point of

common coupling (PCC) at Industry.

At the same time it is the responsibility of the customers not to inject pollutants i.e.,

current harmonics in to the grid. The harmonic limits must be maintained within the

prescribed limit of IEEE 519 standard. The customer also maintain the power factor

near unity or higher than the limit prescribed by the utility. Generally the electricity

charges are directly proportional to energy consumption i.e., active energy. At poor

power factor, the active energy will be same but apparent energy will be high.

Therefore, the utility had to provide more demand (kVA) for the required active power at

lower power factor. The maximum demand recorded during the month will also be

charged. Similarly, at harmonic distortions, the utility had to provide higher short circuit

level and capacity to absorb the pollutants injected at PCC by the industry. These

current harmonics will increase the harmonic voltages (depending on the source

impedance) and the voltage flicker will create in the grid. The current and voltage

10

waveforms will be distorted. The voltage flicker & voltage dips will be observed at PCC.

These flickers will adversely affect other customers which are connected with the same

feeder. Therefore, the utility had to provide higher level of short circuit level to

compensate the voltage dips and to suppress the harmonics in the feeders.

In the arc furnace, the arc voltage is subject to stochastic changes due to the melting

process. There are frequent short circuits between electrodes and scrap-metal charge.

These non-linear fluctuating load currents will create voltage fluctuation (voltage dip) in

the network. Arc movements which result in current fluctuations in the frequency band

0.05 to 30 Hz can affect consumer lighting TV sets, electronic apparatus, etc. The most

sensitive frequency is around 10 Hz where modulation of only 0.2 % on supply voltage

causes visible flicker effects.

Table 1 to 7 give the performance results of billet heaters, surface hardening machines,

induction furnaces and arc furnace. During the detailed study of power supply

parameters, power quality parameters and energy related parameters of billet heaters,

surface hardening machines and induction melting furnaces are studied to identify the

criteria for billet heaters & surface hardening machines to categorize as power intensive

industry. The detailed analysis of all the parameters are discussed below with

illustrations:

Table 1: Power supply particulars of industry. Industry

No. Particulars Type of

industry Billet

heater load (kW) [a]:

furnace capacity (tonne)

Service voltage,

(kV)

Contract demand,

(kVA)

Connected load, (kW)

4.1.1 Kay Jay Forging Billet heater 600 11 1435 1296.83

4.1.2 Happy Forging (billet) Billet heater 4600 66 11000 14000

4.1.3 Emson Forging Billet heater 575 11 1647 1992.699

4.1.4 Sherpur Forging Billet heater 300 11 995 975.48

4.1.5 Turbo Tools Billet heater 200 11 1500 1866.307

4.1.6 Sunitha Bicycle Billet heater 100 11 375 363.758

4.1.7 Eastman Forging Billet heater 400 11 1900 3044.783

4.1.8 Ismeet Forging Billet heater 475 11 955 985.948

11

4.1.9 Leela Forging Billet heater 300 11 750 950

4.1.10 Nicks India Tools Billet heater 175 11 995 1633.284

4.1.11 JVR Forging Billet heater 600 11 3920 3536.7

4.1.12 Perfect Forging Billet heater 100 11 933 1474.998

4.1.13 PS Industries Billet heater 100 11 575 564.376

4.1.14 Global Export Billet heater 90 11 300 324.799

4.1.15 Jai Parvati Billet heater 800 11 2300 2394.744

4.1.16 Samrat Forging Billet heater 300 11 1310 1995

4.2.1 Presto Forging Billet heater 40 11 220 198.29

4.2.2 Nakul Gupta Automobiles

Hardening 50 11 220 249.92

4.2.3 Rama Steel Billet heater 70 11 196 200.248

4.2.4 Happy Forging (hardening)

Hardening 425 66 5250 6000

4.2.5 GNA Enterprises Hardening 600 11 2450 5518.92

4.2.6 GNA Udyog Hardening 420 11 2480 3313.93

4.3.1 Basant metal Works furnace 0.5[a]

11 777 709.891

4.3.2 Garg Furnace furnace 6.0[a]

66 7100 7599

4.3.3 Nidhi Furnace furnace 4.0[a]

11 2500 2250

4.3.4 Raj Furnace furnace 0.3[a]

11 299 299.914

4.3.5 Varun Furnace furnace 4.0[a]

66 6817 5999

4.4 Upper India Arc Furnace 20000 66 20000 29446.42

[a]: production rate in tonne

Table 2: Billet heater load, production rate of furnace and measured voltage dip at PCC (11/66 kV side). Indust

ry. No.

Particulars Billet heater load (kW) [a]: furnace capacity

(tonne)

Service voltage, (kV)

Peak Voltage dip due to load change, %

Billet heaters / surfaces hardening machines

4.2.1 Presto Forging 40 11 0.03

4.2.2 Nakul Gupta Automobiles 50 11 0.09

4.2.3 Rama Steel 70 11 0.09

4.2.4 Happy Forging (hardening) 425 66 0.09

4.1.6 Sunitha Sony Bicycle 100 11 0.09

4.1.13 PS Industries 100 11 0.09

4.1.14 Global Export 90 11 0.09

4.1.5 Turbo Tools 200 11 0.10

4.1.10 Nicks India Tools 175 11 0.18

4.1.4 Sherpur Forging 300 11 0.19

4.1.9 Leela Forging 300 11 0.19

4.1.12 Perfect Forging 100 11 0.19

4.1.16 Samrat Forging 300 11 0.27

4.2.6 GNA Udyog 420 11 0.28

4.1.8 Ismeet Forging 475 11 0.39

4.1.11 JVR Forging 600 11 0.42

4.1.7 Eastman Forging 400 11 0.47

4.1.3 Emson Forging 575 11 0.48

4.2.5 GNA Enterprises 600 11 0.49

4.1.2 Happy Forging (billet) 4600 66 0.53

4.1.1 Kay Jay Forging 600 11 0.65

4.1.15 Jai Parvati 800 11 0.75

12

Induction furnaces

4.3.1 Basant metal Works 0.5[a]

11 0.09

4.3.2 Garg Furnace 6.0[a]

66 0.18

4.3.4 Raj Furnace 0.3[a]

11 0.18

4.3.5 Varun Furnace 4.0[a]

66 0.27

4.3.3 Nidhi Furnace 4.0[a]

11 1.80

Arc Furnaces 4.4 Upper India 20000 66 0.70


Table 3: Computed demand factor and measured SEC. Indust

ry. No.

Particulars Billet heater load (kW)

[a]: furnace capacity (tonne)

Service voltage,

(kV)

Demand factor, %

SEC, kWh/kg or [a]

kWh/piece


4.2.1 Presto Forging 40 11 26.3 - 47.0 0.013 to 0.026[a]

4.2.2 Nakul Gupta Automobiles 50 11 50.1 - 68.6 0.126[a]

4.1.12 Perfect Forging 100 11 72.82 - 96.17 0.22

4.1.13 PS Industries 100 11 70.12 - 89.53 0.22 to 0.49

4.1.14 Global Export 90 11 89.12 - 98.56 0.24[a]

4.2.4 Happy Forging (hardening) 425 66 21.09 - 28.2 0.26 to 0.36[a]

4.2.3 Rama Steel 70 11 27.97 - 64.16 0.29 to 0.54[a]

4.1.16 Samrat Forging 300 11 78.85 - 98.92 0.35

4.1.9 Leela Forging 300 11 70.92 - 98.84 0.37 to 0.58

4.1.4 Sherpur Forging 300 11 51.99 - 76.91 0.39

4.1.11 JVR Forging 600 11 60.54 - 73.03 0.41 to 0.53

4.1.8 Ismeet Forging 475 11 8.34 - 95.35 0.42 to 0.47

4.1.1 Kay Jay Forging 600 11 70.7 - 100.36 0.46 to 0.50

4.1.7 Eastman Forging 400 11 59.51 - 68.76 0.48

4.1.2 Happy Forging (billet) 4600 66 49.43 - 76.94 0.49 to 0.67

4.1.10 Nicks India Tools 175 11 33.67 - 55.61 0.53

4.1.3 Emson Forging 575 11 77.82 - 93.36 0.55 to 0.65

4.1.6 Sunitha Sony Bicycle 100 11 38.71 - 53.54 0.57

4.1.5 Turbo Tools 200 11 47.08 - 62.17 0.58

4.1.15 Jai Parvati 800 11 82.04 - 100.57 0.73

4.2.6 GNA Udyog 420 11 51.68 - 64.42 2.00[a]

4.2.5 GNA Enterprises 600 11 59.02 - 91.59 4.45 to 18.86[a]

Induction furnaces


11 95.68 - 103.63 0.74


66 35.96 - 88.24 0.783


66 60.53 - 87.80 0.816


11 93.13 - 99.79 0.88


11 64.74 - 81.08 0.902

Arc Furnaces 4.4 Upper India 20000 66 70.05 - 79.84 0.455 to 0.669


13

Table 4: Harmonic current, excess demand and capacity loss of distribution system. Industry No.

Particulars Billet heater

load (kW) [a]:

furnace capacity (tonne)

Service voltage,

(kV)

Avg. Current THD, %

Harmonic current, A

Excess demand,

kVA

Excess demand,

%

Capacity loss,

%


4.2.1 Presto Forging 40 11 28.74 1.00 19.7 21.95 0.12

4.2.3 Rama Steel 70 11 25.29 1.32 24.3 27.94 0.21

4.2.2 Nakul Gupta Automobiles

50 11 13.17 2.1 40.0 30.00 0.25

4.1.6 Sunitha Sony Bicycle 100 11 22.85 2.20 41.3 22.79 0.17

4.1.10 Nicks India 175 11 7.81 2.87 54.2 13.65 0.24

4.1.14 Global Export 90 11 25.61 4.09 78.1 4.10 0.36

4.1.9 Leela Forging 300 11 13.38 4.48 81.1 12.46 0.33

4.1.12 Perfect Forging 100 11 8.55 5.12 84.0 24.84 0.43


425 66 4.66 0.80 91.6 7.41 0.03

4.1.5 Turbo Tools 200 11 11.58 5.59 100.2 11.85 0.36

4.1.8 Ismeet Forging 475 11 12.97 5.94 102.3 18.61 0.57

4.1.13 PS Industries 100 11 30.07 5.40 103.8 22.49 0.45

4.1.16 Samrat Forging 300 11 17.53 5.46 106.0 9.35 0.46

4.1.4 Sherpur Forging 300 11 21.04 6.94 109.1 21.34 0.53

4.1.3 Emson Forging 575 11 12.89 6.64 112.3 7.89 0.43

4.2.6 GNA Udyog 420 11 6.17 6.90 112.8 5.08 0.46

4.1.7 Eastman Forging 400 11 4.52 6.54 123.8 5.25 0.42

4.1.11 JVR Forging 600 11 4.52 7.29 128.7 5.01 0.52

4.1.15 Jai Parvati 800 11 13.83 8.50 146.5 6.09 0.71

4.2.5 GNA Enterprises 600 11 10.43 8.74 185.0 13.00 0.66

4.1.1 Kay Jay Forging 600 11 18.53 10.67 190.0 14.90 0.84

4.1.2 Happy Forging (billet) 4600 66 9.17 5.17 597.8 8.56 0.21 Induction furnaces


11 16.93 3.13 59.2 20.50 0.32


11 22.1 5.21 98.12 16.27 0.57


66 8.28 2.37 275.6 6.76 0.1


66 10.18 2.98 347.9 6.59 0.14


11 7.83 18.86 366.2 14.96 2.27

Arc Furnaces

4.4 Upper India 20000 66 6.54 6.36 654.9 4.68 0.6


Table 5: Energy loss in distribution equipment & utility power transformer. Industry No.


(tonne)

Service voltage,

(kV)

Energy loss, kWh/month




14


4.2.3 Rama Steel 70 11 1.90

4.2.2 Nakul Gupta Automobiles 50 11 2.50

4.1.10 Nicks India 175 11 5.46

4.1.14 Global Export 90 11 5.90

4.1.13 PS Industries 100 11 7.94

4.1.9 Leela Forging 300 11 8.64

4.1.12 Perfect Forging 100 11 10.20

4.1.5 Turbo Tools 200 11 11.82

4.1.16 Samrat Forging 300 11 13.56

4.2.6 GNA Udyog 420 11 13.77

4.1.4 Sherpur Forging 300 11 14.80


4.1.8 Ismeet Forging 475 11 22.91

4.1.3 Emson Forging 575 11 25.44

4.1.15 Jai Parvati 800 11 46.91


4.1.1 Kay Jay Forging 600 11 54.62

4.1.11 JVR Forging 600 11 58.09

4.1.2 Happy Forging (billet) 4600 66 59.55 Induction furnaces


11 5.4


66 6.7


66 17.20


11 17.60


11 221.7

Arc Furnaces 4.4 Upper India 20000 66 72.5


Table 6: Energy Intensive Factor for billet heaters, surface hardening machines & induction furnaces. Industry No.


(tonne)

Service voltage,

(kV)

Energy Intensive Factor, kWh/kVA



4.2.3 Rama Steel 70 11 47.82


4.1.4 Sherpur Forging 300 11 101.99 4.2.2 Nakul Gupta Automobiles 50 11 104.75


4.1.10 Nicks India 175 11 125.98

4.1.2 Happy Forging (billet) 4600 66 126.66

4.1.8 Ismeet Forging 475 11 130.49

4.1.12 Perfect Forging 100 11 139.27

4.1.5 Turbo Tools 200 11 168.79

4.1.14 Global Export 90 11 174.42

4.1.11 JVR Forging 600 11 186.75


15


4.2.6 GNA Udyog 420 11 216.07

4.1.3 Emson Forging 575 11 228.07

4.1.15 Jai Parvati 800 11 250.21

4.1.13 PS Industries 100 11 267.60

4.1.16 Samrat Forging 300 11 269.56

4.1.9 Leela Forging 300 11 273.62

4.1.1 Kay Jay Forging 600 11 290.97 Induction furnaces


66 118.30


66 126.75


11 196.27


11 232.63


11 271.32


16

Table 7: Key Parameters of the Report)

Sr. No

Process Voltage dip, % (at PCC)

Avg. Current THD, %

Cap. Loss due to Harmonics, % (at

PCC)

Excess MD, kVA (% of CD)

Demand Factor, %

Avg. energy loss

kWh/month (at PCC)

SEC, kWh/kg of Steel

1 Billet Heater 0.03 to 0.65 1.0 to 10.67 0.12 to 0.84

19.7 to 598 kVA (4.10 to 24.84%)

8.34 to 100.57 0.30 to 58.09 0.24 to 0.83

2 Harding M/Cs 0.09 to 0.47 0.8 to 13.74 0.03 to 0.66

40.0 to 185 KVA (7.41 to 30 %)

21.09 to 91.59 0.73 to 48.43 0.126 to 16.86

3 Induction Furnace

0.09 to 2.05 2.37 to 18.86 0.01 to 2.27 59.2 to 275.6 KVA

(6.59 to 20.5%) 35.96 to 103.63 5.4 to 221.7 0.74 to 0.902

4 Arc Furnace 0.70 6.36 0.6 654.9KVA (4.68%) 70.05 to 79.84 72.5 0.455 to 0.669

Table 8: Overall performance parameters of billet heaters & surface hardening machines.

Sr. No.

Name of Consumer

Billet load Under test,

KVA

Temp. 0C

Peek Voltage dip, %

(at PCC)

Voltage THD, %

Current THD, %

Average

TDD, %

Extra Demand, kVA (at

PCC)

Demand Factor, % (at

PCC)

Energy Loss,

KWh/month (at PCC)

SEC KWh/kg of steel

1a Kay Jay Forging 300 1250 0.65

6.6-8.0 32.6-35.3 24.1 190.0 70.7 - 100.36 54.62

0.50

1b Kay Jay Forging 300 1250 5.9-6.9 31.9-39.6 24.1 0.46

2a Happy Forging 4000, 600 1200 0.53

1.5-3.5 23.2-24.6 12.7 597.8 49.43 - 76.94 59.55

0.493

2b Happy Forging 600 1200 6.1-7.8 25.9-27.5 12.7 0.673

3a Emson Tools 200,175,150 1200

0.48

1.6-6.4 28.3-34.1 23.8

112.3 77.82 - 93.36 25.44

0.63

3b Emson Tools 250 1200 2.62-5.2 28.7-30.0 23.8 0.55

3c Emson Tools 175 1200 0.8-3.8 27.7-29.2 23.8 0.65

4 Sherpur Forging 300 1200 0.19 0.6-8.3 29.3-30.7 30.3 109.1 51.99 - 76.91 14.8 0.39

5 Turbo Tools 200, 200 1200 0.10 1.4-5.2 38.3-54.5 18.02 100.2 47.08 - 62.17 11.82 0.58

6 Sunitha Sony Bicycle

100, 100 1200 0.09 2.7-4.2 25.1-27 31.3 41.3 38.71 - 53.54 1.48 0.57

7 Eastman Cast and Forging

100,150,200 1200 0.47 0.7-5.0 16.8-47.9 9.8 123.8 59.51 - 68.76 21.48 0.48

8a Ismeet Forging 300, 175 1200 0.39

3.7-6.0 27.6-30.4 19.1 102.3 8.34 - 95.35 22.91

0.47

8b Ismeet Forging 175 1200 4.8-8.0 20.9-31.1 19.1 0.42

9a Leela Forging 150 1200 0.18 2.2-5.5 29.2-29.8 22.6 81.1 70.92 - 98.84 8.64 0.58

17

9b Leela Forging 150 1200 2.0-3.8 32.0-40.4 22.6 0.37

10 Nicks India Tools

175 1200 0.18 1.9-5.2 27.2-29.2 23.7 54.2 33.67 - 55.61 5.46 0.53

11a JVR Forging 400, 200 1200 0.42

4.2-5.6 27.7-29.2 21.3 128.7 60.54 - 73.03 58.09

0.53

11b JVR Forging 200 1200 5.2-6.6 28.2-29.0 21.3 0.41

12 Perfect Forging 100, 250 1200 0.19 0.9-2.1 37.2-89.5 3.2 84.0 72.82 - 96.17 10.2 0.22

13a PS Industries (10KVA) 10 1200 0.09

4.0-5.0 55.5-78 35.5

103.8 70.12 - 89.53 7.94

0.39

13b PS Industries 10 1200 3.5-4.3 64.9-79 35.5 0.49

13c PS Industries 10 1200 4-4.5 69.4-80.8 35.5 0.22

14 Global Export 90+90 1150 0.09 2.3-7.5 7.2-40.6 33.8 78.1 89.12 - 98.56 5.90 0.24

15 Jai Parvati 400+400 1200 0.75 8.4-8.8 25.8-26.9 21.8 146.5

82.04 - 100.57

46.91 0.73

16 Samrat Forging 300+300 1200 0.27 1.92-4.1 24.5-43.9 35 106.0 78.85 - 98.92 13.56 0.35

17a Presto Forging 20 1000 0.03

3.0-6.0 6.5-52.5 61.8 19.7 26.3 - 47.0 0.30

0.026

17b Presto Forging 20 1000 2.7-5.0 7.2-61.6 61.8 0.013

18 Nakul Gupta Automobiles

50 950 0.09 2.6-6.7 40.5-53.6 37.3 40.0 50.1 - 68.6 2.50 0.126

19a Rama Steel 35 950 0.09

1.1-3.8 15.3-25.4 55.9 24.3 27.97 - 64.16 1.90

0.29

19b Rama Steel 35 950 1.2-4.0 43.6-45 55.9 0.54

20a Happy Forging 200 1000 0.09

1.9-4.7 30.5-40.3 8.8 91.6 21.09 - 28.2 0.73

0.36

20b Happy Forging 200 1000 1.9-3.4 31.4-39.8 8.8 0.26 21a GNA Enterprises 350 1000

0.49

1.3-9.4 5.1-35.9 24.5

185.0 59.02 - 91.59 48.43

18.85

21b GNA Enterprises 125 1000 1.6-3.6 23.5-29.4 24.5 4.45

21c GNA Enterprises 150 1000 1.2-5.6 1.7-11.1 24.5 15.75

22a GNA Udyog 100 1000 0.28

1-5.9 25.1-29.6 11.1 112.8 51.68 - 64.42 13.77

2

22b GNA Udyog 320 1000 1-3.6 1.7-16.8 11.1 2

18

3.1 Principle of induction heating

The billet heaters, surface hardening machines and induction melting furnaces work on

the same principle of AC variable high frequency power supply. In both cases, the grid

power frequency supply (50 Hz) is converted to DC by rectifiers and inverted back to

varying frequency AC source. The heating effect depends on the frequency i.e., at high

frequency the heating or melting is fast.

The power quality parameters are almost similar in both cases and there is no

difference in power quality parameters like current & voltage harmonics, voltage flicker

and voltage dip.

3.2 Voltage variation

The sudden change in non-linear load due to billet heating and melting of metals cause

dip in voltage which is again depends on network short circuit capacity. During

measurement the non-linear load of 600 kVA was in service. At Kay Jay Forging, during

measurement at 11 kV incomer side, the current is increased from 49.64 A (11:28:50

hours) to 55.7 A (∆I = 6.06 A; a variation of 12.21 %), due to non-linear loading of billet

heaters, this increased current had reduced the voltage at 11 kV side from 10.273 kV to

10.143 kV (∆V = 0.13 kV). The voltage drop is about 1.265 % which is very high. The

average voltage change during the entire measurement is 0.65 % which is on higher

side.

At Nidhi Furnace, during the measurement at main incomer on 11 kV side, the current is

increased from 17.2 A to 121 A (∆I = 103.8 A; variation of 603.5 %), the voltage is

reduced on 11 kV side from 11.450 kV to 11.117 kV (∆V = 0.333 kV). The voltage drop

is 2.91 % which is on higher side. This higher voltage is may be due to the short circuit

MVA is less (11 kV incomer for the contract demand of 2500 kVA).

During measurement at Presto Forging, the non-linear load of 40 kVA was in service,

the current at main incomer on 11 kV side (at 13:27:11 hours) is increased (∆I) from 1.3

19

A to 2.2 A (∆I = 0.9 A; a variation of 69.23 %), the voltage is decreased from 11.420 kV

to 11.417 kV (∆V = 0.003 kV). The voltage dip is 0.026 % which is on lower side.

Figure 5 gives the variation of average voltage dip for different billet heater and

induction hardening machines and Figure 6 shows the variation voltage dip for induction

furnaces. The average voltage dip is measured in the range of



• Induction furnaces: 0.09 to 2.05 % and


It can be seen from the Figures that the voltage drop on 11 kV side increases with the

increase in non-linear load i.e., capacity of induction billet heater / hardening machines.

Generally, the utility must maintain the voltage variation at customer as per Indian

Electricity Rules 1956 (IE Rule) Rule No. 54:

• Low voltage : ± 6.0 %

• High Voltage : + 6.0 % and – 9.0 %

• Extra High Voltage: + 10 % and -12.5 %.

As per the IE rules 1956 rule No. 2, 11 kV is treated as High voltage and above 33 kV is

treated as EHV.

Therefore, the voltage variation for 11 kV system must be + 6.0 % and - 9.0 % at PCC.

During the power supply measurement at PCC of industries at M/s. Kay Jay Forging

where non-linear load 600 kVA (two numbers of 300 kVA) billet heaters were in service.

The average voltage dip due to load change was measured as 0.65 %. Similarly at Jai

Parvti Forging, the voltage dip was 0.75 % (400 kVA x 2 billet heaters), at Emson

Forging the voltage dip is 0.48 % (150 kVA + 250 kVA + 175 kVA billets were in service

during measurement). The average voltage drop (curve fit value from graph) at 500 kVA

non-linear load (billet heater load) is about 0.40 %.

20

For 11 kV system, the ACSR conductor size used will be copper equivalent of 65 mm2

i.e., ‘DOG’ conductor. The current rating of this conductor at 45 oC is 300 A (refer

Figure 6: Variation of voltage drop at main incomer for induction furnaces.

Figure 5: Variation of voltage drop at main incomer for billet heaters.

21

Annexure III). The average current of each industry connected at 11 kV system is about

50 A. Six industries can be connected on this feeder. The total voltage drop due to six

industries in one feeder is 6 x 0.30 % (average value from curve fit) = 1.8 %.

To compute the voltage drop (provided by PSPCL) method through kVA-km method is

as follows:

If there are 6 numbers of consumers whose average non-liner load of 600 kVA each at

a uniform distance of 1 km from sub-station. The conductor used is ‘DOG’ (ACSR: 65

mm2). As per the Standard Instruction Nos. 44 & 46 of PSPCL guidelines:

Total KVA – KM as computed from tail end.

KVA – KM (600+1200+1800+2400+3000+3600)

KVA – KM = 12,600

As per voltage regulation equation

100 x VD = 4.09 X1 + 4.97X + 6.69Y + 10.17Z

X1 ; is KVA KM of 65 mm2 ACSR ; KVA – KM of other conductor sizes will be zero

100X VD = 4.09 x 12600 = 515.34 Volts

Voltage regulation: 515.34 * 100 / 11000 = 4.68 %

Therefore, the estimated voltage drop for 11 kV feeder for average distance of 6 km is

4.68 % (data provided by PSPCL)

The total voltage drop due to non-linear load of average six industries (having a non-

linear load of 500 kVA each) and the voltage drop due to resistance of conductor is (2.4

+ 4.68 ) = 7.08 %. Considering the diversity factor of 70 % for industrial load, the voltage

drop will be 4.96 %. This voltage drop is not in the control of utility and is due to



22



The total voltage drop due to non-linear load of average six industries and the voltage

drop due to resistance of conductor is (2.4 + 4.68 ) = 7.08 %. Considering the diversity

factor of 70 % for industrial load, the voltage drop will be 4.96 %. Moreover this voltage

drop is not constant but will be varying continuously which may affect other equipments

(refer Figures 7 to 9). This voltage drop is not in the control of utility and is due to





If a non-linear load of about 2000 kVA is considered at 11 kV i.e., at Nidhi Steel, the dip

due to sudden load change is 1.8 %. The total voltage dip due to non-linear load of 6

industries will be 10.8 % and voltage drop due to conductor resistance is 4.68 %.

Figure 7: Variation of voltage & current at Kay Jay Forging main incomer.

23

Therefore, the total voltage drop will be 15.48 % which is very high for the utility to

maintain the power supply parameters as per IE rules. Even if 1000 kVA is considered

at 11 kV, the estimated voltage drop due to power quality will be 1.0 % and total voltage

dip due to non-linear load of 6 industries will be 6.0 % and voltage drop due to

conductor resistance is 4.68 %. Total voltage drop will be 10.68 % which is on higher

side.

If the bulk non-linear load, started suddenly, the voltage will drops down and will affect

the voltage at grid also. But the voltage dip at the grid depends on the circuit level of

network of industry as well as grid short circuit level. On the other hand, while the bulk

non-linear load stopped suddenly, the voltage may raise and affect the grid. Therefore,

for starting of bulk non-linear load must have sufficient short circuit level for smooth

operation. The utilities may also operate number of power transformers in parallel to

provide higher level of short circuit level.

Figure 8: Variation of voltage & current at Jai Parvati Forging main incomer.

24

In order to maintain the voltage fluctuation within the limits, the utility may have to

provide the connection by next higher voltage rating for which the utility had to incur

additional expenditure. Generally, for providing the power supply connection to

industries, 11 kV power supply will be fed to the customers whose contract demand is

up to 2500 kVA. For above 2500 kVA, the utility is providing 66 kV power supply.

At Varun steel industries, during the measurement at 66 kV incomer side, the current is

suddenly changed from 5.1 A to 14.1 A (∆I = 9.0 A: variation of 176.5 %), the voltage is

dropped from 67.80 kV to 67.62 kV (∆V = 0.18 kV; drop of 0.27 %). The voltage drop is

0.27 %.

At Happy Forging (billet heaters), during the measurement at 66 kV incomer side, the

current is increased from 53.1 A to 53.7 A (∆I = 0.6 A; variation of 1.13 %), the voltage

is dropped from 67.80 kV to 67.44 kV (∆V = 0.36 kV). The voltage drop is 0.53 %.

At Happy Forging (induction hardening machines), during the measurement at 66 kV

incomer side, the current is suddenly changed from 10.9 A to 11.9 A (∆I = 1.0 A:

variation of 9.17 %), the voltage is dropped from 66.00 kV to 65.94 kV (∆V = 0.06 kV;

drop of 0.09 %). The voltage drop is 0.09 % which is on lower side.

Figure 9: Variation of voltage & current at Presto Forging main incomer.

25

As per IE rules 1956 Rule No. 2, 66 kV voltage distribution is considered as EHV and

the voltage variation limit is + 10 % and -12.5 %. During the power supply

measurement at PCC of industries at M/s. Varun Steel industries where non-linear load

2000 kVA (induction melting furnace i.e., one number of 4 tonne melting furnace) was in

service. The voltage dip due to load change was measured 0.27 %.

3.3 Voltage Flicker

The non-linear loads like induction billet heaters, surface hardening machines and

induction furnaces, generate inter harmonics in the system. The inter harmonics are not

the integer value of the harmonics. These inter harmonics create the voltage flicker in

the system. The integer harmonics can be suppressed by installing the harmonic filters

but it is very difficult to suppress the inter harmonics which cause voltage flicker in the

system. These voltage flickers cause inconvenience to the human eyes. The flicker

limits as per IEEE Standard 1453 – 2004 (refer Figure 10), “Measurement and limits of

Voltage Fluctuations and Associated Light Flicker on AC Power Systems”.

Figure 10: Range of Observable and Objectionable Voltage Flicker versus Time (IEEE standard 1453-2004)

26

IEC flicker meter’s output is simple: if the output is greater than 1.0, the flicker is

generally irritable to humans; if less than 1.0, it is not. These results have been

successfully validated with many years of real world testing in several countries. The

flicker meter’s main output is in a unit called PST, meaning, “Perception of light flicker in

the short term.”

This standard adopts IEC-61000-4-15 – 2003, which gives details for flicker calculations

and measurements. As per IEC standard the voltage flicker will be measured by using

flicker meter which is in-built in the power quality analyser and give the measurement

value of PST i.e., short term flicker which will take the average value of 10 minute

readings. The long term flicker is computed by taking the measurement for 2 hours (i.e.,

12 readings of PST values each of 10 minutes). The PLT is computed as

31

3

N

P

P

N

i

STi

LT

∑=

=

Where N is the number of PST periods within the observation time of PLT i.e., 12 PST (10

minutes) measurements

The limit for PST is 1.0 and PLT is 0.8 (IEC 61000-3-7). During the field measurement

study for billet heaters and surface hardening machines, the voltage flickers are

measured for different billet heaters and at main incomer also.

Figure 11 gives the variation of voltage flicker ‘PST’ values at 10 kVA billet heater at PS

industries. Figure 12 gives the variation of voltage flicker ‘PST’ values at main incomer at

11 kV at PS industries (during measurement 10 numbers of 10 kVA billet heaters were

in service).

27

It can be seen from the above Figures that the maximum voltage flicker at billet heater

is measured as 0.55 whereas at main incomer side the voltage flicker is 0.17. The

voltage flicker readings are well within the permissible limit of IEC.

Figure 13 gives the variation of voltage flicker ‘PST’ values at 300 kVA billet heater at

Sherfur Forging. Figure 14 gives the variation of voltage flicker ‘PST’ values at main

incomer at 11 kV at Sherfur forging (during measurement one number of 300 kVA billet

heater was in service).

Figure 12: Variation of voltage flicker at incomer at PS Industries.

Figure 11: Variation of voltage flicker at Billet heater at PS Industries.

28



voltage flicker readings are well within the permissible limit of IEC.

Figure 15 gives the variation of voltage flicker ‘PST’ values at 400 kVA billet heater at Jai

Parvati Forging. Figure 16 gives the variation of voltage flicker ‘PST’ values at main

incomer at 11 kV at Jai Parvati forging (during measurement two numbers of 400 kVA

billet heaters were in service).

Figure 14: Variation of voltage flicker at incomer at Sherfur Forging.

Figure 13: Variation of voltage flicker at Billet heater at Sherfur Forging.

29



voltage flicker readings are higher the permissible limit of IEC at billet heaters.

3.4 Harmonic current

The equivalent harmonic current component is computed as

AIIcurrentHarmonicAveragei

ih ∑=

=50

3

2

Where Ii is the individual current harmonics from 3rd order to 50th order.

Figure 16: Variation of voltage flicker at incomer at Jai Parvati Forging.

Figure 15: Variation of voltage flicker at billet heater at Jai Parvati Forging.

30

Figure 17 gives the variation of average harmonic current for different billet heater and

induction hardening machines and Figure 18 shows the variation of harmonic current for

induction furnaces. The average harmonic current is measured in the range of

• Billet heaters: 1.0 to 10.67 A

• Hardening machines: 0.80 to 13.74 A

• Induction furnaces: 2.37 to 18.86 A and

• Arc Furnace : 6.36 A

It can be seen from the Figures that the harmonic current increases with the increase in


induction billet heaters, hardening machines and induction furnaces, the harmonic

current is almost same but in case of Nidhi Furnace the harmonic current is high

because the contract demand is 2500 (during study only one furnace of 4.0 t capacity

furnace was in service) & is connected with 11 kV system. But on the other hand at

Varun Furnace the harmonic current is 2.37 A & is less because the incoming power

supply voltage is 66 kV. During the measurements, at both these industries, only one

induction furnace of 4.0 t capacity was in service. Therefore, to compensate the

harmonic current at PCC, higher short circuit level (i.e., higher impedance level of utility

grid) is required to suppress the harmonic currents.

Figure 17: Variation of harmonic current at main incomer for billet heaters.

31

3.5 Current & Voltage Waveforms

Due to non-linear loading, the current waveform is distorted (Figure 19: Current

waveform of 400 kVA billet heater at Jai Parvati Forging). This non-linear loading

distorts the voltage waveform at billet heater (Figure 20). It can be seen from the

waveform the current THD of 26.71 % distorts the voltage THD to 15.13 %. This billet

heater load (400 kVA load) distorts the current waveform at main incomer at 11 kV THD

is 12.62 % (2 x 400 kVA load) (Figure 21) and voltage waveform THD is 2.17 % (Figure

22). Therefore, the non-linear loading of billet heaters distort the voltage waveform and

pollute power quality of the utility grid. Similarly voltage & current waveforms at Sunitha

Sony Bicycle (100 kVA billet heater load) & Leela forging (300 kVA billet heater load) is

given in Figures 23 to 34

Figure 18: Variation of harmonic current at main incomer for induction furnaces.

32

Figure 25: Current waveform at Main incomer (800 KVA)

Figure 23: Current waveform at Billet heater (400 KVA)

Figure 24: Voltage waveform at Billet heater (400 KVA).

33

Figure 28: Voltage waveform at Billet heater (100 KVA)


Figure 26: Voltage waveform at Main incomer (800 KVA)

34


Figure 30: Voltage waveform at Main incomer (100 kVA)


35

Figure 34: Voltage waveform at Main incomer (300 kVA)


Figure 32: Voltage waveform at Billet heater (300 KVA)

36

3.6 Capacity reduction of utility distribution system

The presence of harmonics in the system reduces the capacity of distribution capacity

of utilities i.e., transformers, overhead lines, cables, circuit breakers, etc.

The capacity loss is computed as:

%100*

TR

h

I

IlossCapacity =

Where ITR is the rated current of power transformer at utility sub-station (i.e., 1049.7 for

11 kV & 874.77 A for 66 kV lines) or conductor rated current or circuit breaker current in

A.

The approximate capacity loss due to harmonics present in industries at PCC are

computed. Figure 35 gives the variation of capacity reduction of distribution system due

to presence of harmonics at PCC for billet heaters and hardening machines and

Figure 36 shows the variation of capacity reduction of distribution system for induction

furnaces. The average distribution capacity reduction is computed as:





It can be seen from the Figures that the capacity loss increases with the increase in



almost same but in case of Nidhi Furnace the capacity loss is high because the contract

demand is 2500 (during study only one furnace of 4.0 t capacity furnace was in service)

& is connected with 11 kV system. But on the other hand at Varun Furnace the capacity

loss is 0.1 % & is less because the incoming power supply voltage is 66 kV. During the

measurements, at both these industries, only one induction furnace of 4.0 t capacity

was in service. Similarly at Happy forging where surface hardening machines are

37

installed and incoming voltage is 66 kV, the distribution capacity loss is very less of

about 0.03 %.

Figure 36: Variation of Capacity reduction of distribution system at Induction furnaces.

Figure 35: Variation of Capacity reduction of distribution system at Billet heaters.

38

3.7 Excess Demand

The harmonic current increases the true maximum demand will increase but the static

energy meters will record only RMS value of maximum demand. The excess MD due to

the presence of harmonic current at PCC is computed as:

kVAIVKVAdemandExcess havexcess **3=

Where Vav is the average voltage in kV at main incomer.

The percentage of excess demand is computed as:

%100*

av

excess

MD

KVAdemandExcess =

Where MDav is the average maximum recorded for period of one and half year.

Figure 37 gives the variation of excess demand due to presence of harmonics at PCC

for billet heaters and hardening machines and Figure 38 shows the variation of excess

demand for induction furnaces. The average excess demand is computed as:

• Billet heaters: 19.7 to 597.8 kVA (4.10 – 24.84 %)

• Hardening machines: 40.0 to 185.0 kVA (7.41 – 30.0 %)

• Induction furnaces: 59.2 to 275.6 kVA (6.59 – 20.5 %)

• Arc Furnace: 654.9 kVA (4.68 %)

It can be seen from the Figures that the excess demand increases with the increase in



almost same.

39

3.8 Power Factor

The non linear load will not exhibit true power factor. The true power factor of non linear

load (where harmonic currents are present) consists of two parameters i.e.,

dispacement factor and distortion factor.

Figure 38: Variation of Excess demand at Induction furnaces.

Figure 37: Variation of Excess demand at Billet heaters.

40

FactorDistortionFactortDispacemenPFtrue *=

2

1001

1*

*

+

=

Iavgavg

avg

true

THDIV

PPF

Where Pavg is the average RMS power in Watt, Iavg is the RMS current in Amps, Vavg is

the RMS voltage in V and

%100*2

2

RMS

k

kRMS

II

I

THD

∑∞

==

The distortion factor is inversly proportional to current THD. Therefore, as the current

THD increses, the true power factor will become less. For a non liners load even if their

displacement factor is better but the true power factor will be low.

Figure 39 gives the variation of true power factor with current THD. Therefore, all these

induction billet heaters, surface hardening machines and induction furnaces exhibit

higher current THD which cause lower true power factor.

Figure 39: Variation of True power factor with current THD (Ref: W. Mack Grady & Robert J. Gilleskie, ‘Hormonics & how they relate to

power factor’, Proc. of the EPRI Power Quality Issues & Opportunities Conference (PQA’93), San Diego, CA, November 1993).

41

3.9 Demand Factor

Since the concern is with respect to power or demand not with energy parameters,

therefore, the demand factor is essential. The demand factor is computed as:

%kVAindemandcontract

kVAindemandrecordedormeasuredActualfactorDemand =

The demand factor is varying in the range of:

• Billet heaters: 8.34 to 100.57 %; At few industries like Nicks India, Turbo tools,

Sunitha Bicycle & Presto Forging is less may be due to lower rating of

billet heaters are used.

• Hardening machines: 21.09 to 91.59 %; At Happy forging the demand factor is

less may be due to contact demand is high.


• Arc Furnace: 70.05 to 79.84 %

The demand factors for all billet heaters, induction hardening machines, induction

furnace and arc furnaces is almost same. And there is no significant difference in

demand factor for all these machines.

3.10 Energy loss in utility distribution system

The presence of harmonics in the system i.e., current harmonics from the industry leads

to voltage harmonics and voltage harmonics increases the iron losses (hysteresis loss α

frequency & eddy current losses α square of frequency) of utility power transformers.

( )2frequencylossescurrentEddy α

frequencylossesHysterisis α

The current harmonics increases the utility power transformer winding losses and

conductor losses.

Figure 40 gives the variation of energy loss in utility power transformers due to

presence of harmonics at PCC for billet heaters and hardening machines and Figure 41

42

shows the variation of energy loss in utility power transformers for induction furnaces.

The average energy loss is computed as:

• Billet heaters: 0.30 to 58.09 kWh/month

• Hardening machines: 0.73 to 48.43 kWh/month

• Induction furnaces: 5.4 to 221.7 kWh/month

• Arc Furnace: 72.5 kWh/month

It can be seen from the Figures that the energy loss in utility power transformer

increases with the increase in non-linear load i.e., capacity of induction billet heater /

hardening machines. But the energy loss due to Nidhi furnace is very high because the

harmonic current is high and the main incoming voltage is 11 kV.

In most of the induction billet heaters, hardening machines, induction furnaces and arc

furnaces, the impact of energy loss in utility power transformer is almost same but

depends on the utility voltage level of power supply at PCC.

Figure 40: Variation of Energy loss in distribution system for Billet heaters.

43

3.11 Specific Energy Consumption

In the billet heaters the energy is used to only heat the billets of smaller size and there

is no change in phase. But in case of induction melting furnaces, while heating the iron

is converted from solid to liquid i.e., phase change. In induction furnace, the melting

temperature is higher in the range of 1500 – 1600 oC compared to billet heaters in the

range of 1200 – 1250 oC & surface hardening machines in the range of 950 – 1150 oC.

At higher temperature, the steel resistivity will be very high which draws higher current

and hence the SEC will be high. Thus the energy used at induction furnace is higher

compared to billet heaters and surface hardening machines. The SEC is computed by

periodtimeparticularinnconsumptioEnergy

weightorpiecesofnumberineitherperiodtimeparticularinoductionSEC

Pr=

Figure 41: Variation of Energy loss in distribution system for Induction furnaces.

44

Figure 42 gives the variation of SEC for billet heaters and hardening machines and

Figure 43 shows the variation of SEC for induction furnaces. The average SEC for

different machines is:

• Billet heaters: 0.24 to 0.83 kWh/kg of steel; but at presto forging the SEC is in the

range of 0.013 to 0.026 kWh/piece of tools and is very less because the heating

will takes place at hardly 25 to 35 mm at front portion of tools which is forged only

front portion.

• Hardening machines: 0.126 to 18.86 kWh/piece of surface hardening and is

varying widely may be due to varying in temperature and different surface area.

• Induction furnaces: 0.74 to 0.902 kWh/kg of steel and is high slightly high

compared to billet heater may be because of higher temperature requirement &

phase change of material.

• Arc Furnaces: 0.455 to 0.669 kWh/kg of steel and is comparable with both billet

heaters and induction furnaces.

Figure 42: Variation of SEC at Billet heaters

45

It can be seen from the Figures that the SEC increases with the increase in non-linear

load i.e., capacity of induction billet heater / hardening machines whereas in case of

induction furnaces as the capacity of induction furnace increases the SEC decreases.

3.12 Energy Intensive Factor

The energy intensive factor (EIF) is the ratio of monthly energy consumption to the

allotted contract demand (CD). This factor will shows the energy consumption for one

kVA of contract demand. The EIF is computed by

kVAkWhkVAinCDDemandContract

monthkWhinnConsumptioEnergyMonthlyEIF /

)(

/=

Figure 44 gives the variation of energy intensive factor for billet heaters and hardening

machines and Figure 45 shows the variation of energy intensive factor for induction

furnaces. The average EIF for different machines is:

Figure 43: Variation of SEC at Induction furnaces

46

• Billet heaters: 101.99 to 290.97 kWh/kVA; this energy intensive factor will depend

on the production level and vary widely.

• Hardening machines: 47.19 to 216.07 kWh/kVA; this energy intensive factor will

depend on the production level and vary widely.

• Induction furnaces: 118.30 to 271.32 kWh/kVA; this energy intensive factor will

depend on the production level and vary widely.

Sometime the industry may operate 3-shift operation if production demand is more but

the contract demand will be same, in that case the energy intensive factor will increase.

If the production output requirement is less (i.e., industry may operate at partial load or

single shift operation), the energy intensive factor will be low. The behavior of all billet

heaters, hardening machines and induction furnaces are almost same with respect of

energy intensive factor and the value varies widely. Therefore, it is very difficult to

differentiate billet heaters, hardening machines and induction furnaces with respect to

energy intensive factor. But it can be seen from the Figures that as the billet heater load

or induction furnace capacity increases, the energy intensive factor increases slightly.

Figure 44: Variation of EIF at Billet heaters

47

3.13 Overall Appraisal

Therefore, it is very difficult to differentiate billet heater and induction melting furnace as

far as power quality and power supply parameters are concerned but SEC will be less

for billet heaters compared to induction melting furnace. But the concern is with power

or demand and not with energy consumption.

Therefore, the utility must provide higher level of short circuit MVA to absorb the power

quality pollutants created by the industry which is having a larger capacity of non-liner

loads. The utilities to overcome these issues of power quality and voltage fluctuations in

the grid, they are declaring industries whose loading pattern is non-linear as power

intensive industries.

"The Billet heaters and surface hardening machines can be considered as power



Figure 45: Variation of EIF at Induction furnaces

48

with respect to power supply and power quality parameters for billet heaters,

surface hardening machines & induction furnaces are same. The impact of power

quality parameters like voltage dip, voltage flickers, voltage & current waveform

distortions, harmonics, capacity loss of utility distribution system, demand

factor, energy loss in distribution system, etc; all have same effect. Only the

specific energy consumption for induction furnaces is slightly higher compared

to billet heaters due to the change of state of material from solid to liquid &

higher degree of melting temperature”.

The non-linear load is the load where the current is not proportional to voltage


induction billet heaters, induction surface hardening machines, induction




4.0 FIELD MEASUREMENTS, OBSERVATIONS, STUDY RESULTS AND DISCUSSIONS

Field measurements were carried out for the following industries:

1) Induction billet heaters:

a. Kay Jay forging

b. Happy Forging (billet)

c. Emson Tools

d. Sherpur Forging

e. Turbo Tools

f. Sunitha Sony Bicycle

g. Eastman Cast & Forge

h. Ismeet Forging

i. Leela Forging

j. Nicks India Tools

49

k. JVR Forging

l. Perfect Forging

m. PS Industries

n. Global Export

o. Jai Parvati Forging

p. Samrat Forging

2) Induction Surface Hardening Machines:

a. Presto Forging

b. Nakul Gupta Automobile Parts

c. Rama Steel

d. Happy Forging (Hardening)

e. GNA Enterprises

f. GNA Udyog Ltd.

3) Induction melting furnaces:

a. Garg Furnaces

b. Raj Furnaces

c. Basant Metal works

d. Nidhi Steel Industries

e. Varun steel casting

4) Arc Furnace: Upper India Steel Industries

In all above industries, the power supply parameters are recorded at individual furnaces

/ heaters and also at main incomer. The results are discussed below:


4.1.1 Kay Jay Forging

The power is tapped at 11 kV from the PSPCL grid. The contract demand is 1435 kVA

and connected load is 1296.83 kW. At Kay Jay forging, two numbers of billet

heaters of 300 kW are used to heat the billets to the temperature in the range of 1150

to 1250 oC. The power supply parameters are recorded for billet heaters and at main

incomer.

50

Figures 46 to 52 give the variation of power supply parameters at Billet heater 1. The

rating of billet heater 1 is 300 kW (make: Inductotherm). This billet heater is heating the

iron rod for forging. The rod piece average weight is 1318.25 grams, the output is 5

pieces per minute and the total mass output for a time period of 32 minutes is 210.92

kg. The electrical energy consumption is 105.997 kWh for 32 minutes. The Specific

energy consumption (SEC) is 0.50 kWh/kg of steel. Observations on the power

supply parameters are as follows:

a) The voltage at billet heater was varying widely due to non-linear loading.

b) The voltage THD was in the range of 6.6 % - 8.0 % and is on higher side

c) The current THD was in the range of 32.6 % to 35.3 % and is on higher side.


rating of billet heater 2 is 300 kW (make: Inductotherm). This billet heater is heating the

iron rod for forging. The rod piece average weight is 1490.33 grams, the output is 4.5

pieces per minute and the total mass output for a time period of 31 minutes is 207.9 kg.

The electrical energy consumption is 94.854 kWh for 31 minutes. The Specific energy

consumption (SEC) is 0.46 kWh/kg of steel. Observations on the power supply

parameters are as follows:


b) The voltage THD was in the range of 5.9 % to 6.9 % and is on higher side


Figures 60 and 61 give the variation of recorded demand and energy consumption for

last one year (past data from energy bill). The total connected load is 1296.83 kW and

contract demand is 1435 kVA. The demand factor is 70.70 to 100.36 % based on past

data. The utility factor during the power measurement was measured as 75.60 %.

Figures 62 to 72 give the variation of power supply parameters at Main incomer.

Observations on the power supply parameters are as follows:

a) The voltage at inlet was varying between 10.14 to 10.36 kV and is on lower side.

b) The voltage total harmonic distortion (THD) was measured in the range of 1.4 % to 1.9

% and is lower than the limit prescribed by IEEE 519 standard. The individual harmonics

51

were less than prescribed limit of 5.0 %. As per the IEEE-519-1992 standard, the

voltage THD be limited to a maximum value of 5.0 % with no individual voltage harmonic

to exceed 3.0 %, for the voltage up to 69 kV (refer Table 9).

c) The current is varying between 42.9 A to 61.7 A and is changing due to varying load.

d) The current total demand distortion (TDD) was measured in the range of 14.0 % to 24.1

%. The current TDD is considered depending on the average current during the power

measurement and the average current is 51.58 A.

1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

ISC =1049.73*100*1.075/10.32 ≈ 10935 A

ISC/IL = 10935/51.58 = 212

The ISC/IL ratio at peak power is 212 which is more than 100 and less than 1000. The

TDD must be less than 15.0 % as per the Table 10 but the actual measured value is

24.1 % which is higher than the limit. But the TDD is varying widely at partial load.

e) The peak voltage change at main incomer (i.e., at point of common coupling) due

to peak load variation is 0.65 % and is on higher side.

Table 9: Voltage Distortion Limits as per IEEE 519 standard

Voltage Distortion Limits

Bus Voltage At PCC Individual Voltage Harmonic

Distortion, % Total Harmonic

Distortion, THD %

Below 69 kV 3.0 5.0

69 kV to 138 kV 1.5 2.5

138 kV and above 1.0 1.5

4.1.2 Happy Forging


and connected load is 14000 kW. During power measurement at Happy forging, one

number of billet heater of 4000 kW was working and the power is fed for this billet

heater is from two transformers & rectifier units of 2400 kW & 1600 kW. Another billet

heater of 600 kW was also working during the power measurement. The power supply

52

parameters are recorded for 4000 kW billet heater, 600 kW billet heater and at main

incomer. The temperatures maintained in the billet heaters are in the range of 1150 to

1250 oC.

Table 10: Current Distortion Limits for General Distribution Systems (120 V through 69.0 kV)

Maximum Harmonic Current Distortion, % of IL

Individual Harmonic Order (Odd Harmonics)

ISC / IL < 11 11 < h < 17 17 < h < 23 23 < h < 35 35 < h TDD

<20* 4 2 1.5 0.6 0.3 5

20 < 50 7 3.5 2.5 1 0.5 8

50 < 100 10 4.5 4 1.5 0.7 12

100 < 1000 12 5.5 5 2 1 15

> 1000 15 7 6 2.5 1.4 20

Even harmonics are limited to 25 % of the odd harmonic limits above.

Current distortions that result in a dc offset, e.g., half – wave converters, are not allowed.

*All power generation equipment is limited to these values of current distortion, regardless of actual ISC / IL

Where ISC = Maximum Short – circuit current at PCC IL = Maximum demand load current ( fundamental frequency component at PCC)

The billet Heater 1 is rated for 4000 kVA and is provided power supply from two

transformers of 2400 kVA & 1600 kVA. This billet heater is heating the iron rod for

forging. The rod piece average weight is 82 kg, the output is 51.4 pieces per hour and

the total mass output for a time period of 15 minutes is 1053.7 kg. The electrical energy

consumption is 519.64 kWh for 15 minutes. The Specific energy consumption (SEC)

is 0.493 kWh/kg of steel. Observations on the power supply parameters are as follows:

a) The voltage fluctuation is on higher side.

b) The voltage THD at 2400 kVA TR was in the range of 1.5 to 3.5 % and at 1600

kVA TR was in the range of 1.9 to 3.4 %. The voltage THD is normal.

c) The current THD at 2400 kVA TR was in the range of 8.3 to 27.8 % and at 1600

kVA TR was in the range of 23.2 to 24.6 %. The current THD is on higher side.

53


rating of billet heater 2 is 600 kW. This billet heater is heating the iron rod for forging.

The rod piece average weight is 6 kg, the output is 85.7 pieces per hour and the total

mass output for a time period of 20 minutes is 171.4 kg. The electrical energy

consumption is 115.445 kWh for 20 minutes. The Specific energy consumption

(SEC) is 0.673 kWh/kg of steel. Observations on the power supply parameters are as

follows:

a) The voltage fluctuation is on higher side.

b) The voltage THD was in the range of 6.1 to 7.8 % and is on higher side.

c) The current THD was in the range of 25.9 to 27.5 % and is on higher side.


last one year (past data from energy bill). The total connected load is 14000 kW and

contract demand is 11000 kVA. The demand factor is 49.43 to 76.94 % based on past

data. The utility factor during the power measurement was measured as 58.92 %.



a) The voltage at inlet was varying between 65.46 to 68.16 kV and is on normal.






c) The current is varying between 32.19 A to 55.9 A and is varying widely due to varying

load.




1.075% Im

FLSC

II X

pedance voltage= A

54

Axx

I FL 32.26240.66*3

10003100==

ISC =2624.32*100*1.075/15.02 ≈ 18783 A

ISC/IL = 18783/50.19 = 374


TDD must be less than 15.0 % as per the Table 3 but the actual measured value is 12.7

% which is lower than the limit.

4.1.3 Emson Tools


and connected load is 1992.699 kW. At Emson Tools, two numbers of 250 kVA, one

200 kVA, one 175 kVA & one 150 kVA billet heaters are installed to heat the billets to

the temperature in the range of 1100 to 1200 oC. The power supply parameters are

recorded for billet heaters and at main incomer.


rating of billet heater 1 is 150 kVA. The design frequency is 3 kHz but the operating was

about 70 % loading i.e., frequency of 2100 Hz. This billet heater is heating the iron rod

for forging. The rod piece average weight is 1000 grams, the average time taken by

each billet is 19.85 sec. The average production rate is 181.36 kg/h. The average

electrical energy consumption for one hour is 114.26 kWh/h. The Specific energy




b) The voltage THD was in the range of 1.6 – 6.4 % and is on higher side



rating of billet heater 2 is 250 kVA (make: Electrotherm). The design frequency is 3 kHz

but the operating was about 80 % loading i.e., frequency of 2400 Hz. This billet heater is

heating the iron rod for forging. The rod piece average weight is 1700 grams, the

average time taken by each billet is 19.57 sec. The average production rate is 308.39

55

kg/h. The average electrical energy consumption for one hour is 157.73 kWh/h. The

Specific energy consumption (SEC) is 0.55 kWh/kg of steel. Observations on the

power supply parameters are as follows:













b) The voltage THD was in the range of 0.8 to 3.8 % and is normal.



last one year (past data from energy bill. The peak demand factor is 77.82 to 93.36 %

based on past data. The demand factor during the power measurement was measured

as 50.15 %. Figures 119 to 132 give the variation of power supply parameters at Main

incomer. Observations on the power supply parameters are as follows:

a) The voltage at inlet was varying between 11.25 to 11.65 kV and is normal.







56




1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

ISC =1049.73*100*1.075/10.05 ≈ 11228 A

ISC/IL = 11228/32.67 ≈ 344




4.1.4 Sherpur Forging


and connected load is 975.48 kW. At Sherpur Forging (Safe Engineering), one

number of 300 kVA billet heater is installed to heat the billets to the temperature in the

range of 1300 to 1350 oC. The power supply parameters are recorded for billet heaters

and at main incomer.

Figures 133 to 141 give the variation of power supply parameters at Billet heater. The

rating of billet heater is 300 kVA. The design frequency is 3 kHz but the operating was










57
















1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

ISC =1049.73*100*1.075/10.05 ≈ 11228 A

ISC/IL = 11228/21.59 ≈ 520




4.1.5 Turbo Tools


and connected load is 1866.307 kW. At Turbo Tools, two numbers of 200 kVA billet

heaters are installed but only one billet heater was in service to heat the billets to the

temperature in the range of 1150 to 1200 oC. The power supply parameters are


58










b) The voltage THD was in the range of 1.4 to 5.2 % and is on higher side

















1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

ISC =1049.73*100*1.075/9.35 ≈ 12069 A

59

ISC/IL = 12069/28.59 ≈ 422




4.1.6 Sunitha Sony Bicycle


and connected load is 363.758 kW. At Sunitha Sony Bicycle, two numbers of 100

kVA billet heaters are installed but only one billet heater was in service to heat the

billets to the temperature in the range of 1100 to 1200 oC. The power supply parameters

are recorded for billet heaters and at main incomer.




for forging. The rod piece average weight is 550 grams, the average time taken by each

billet is 11.99 sec. The average production rate is 165.21 kg/h. The average electrical

energy consumption for one hour is 94.17 kWh/h. The Specific energy consumption


follows:





last one year (past data from energy bill. The peak demand factor is 38.71 – 53.54 %





60










1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

ISC =1049.73*100*1.075/9.26 ≈ 12184 A

ISC/IL = 12184/7.0 ≈ 1741

The ISC/IL ratio at peak power is 1741 which is more than 1000. The TDD must be less

than 20.0 % as per the Table 10 but the actual measured value is 31.3 % which is higher

than the limit. But the TDD is varying widely at partial load.

4.1.7 Eastman Cast & Forge


and connected load is 3044.783 kW. At Eastman Cast & Forge, three numbers of 200

kVA billet heaters are installed but only two billet heaters were in service to heat the

billets to the temperature in the range of 1150 to 1200 oC. Apart from billet heaters,

induction furnaces of 100 kW, 150 kW & 200 kW each are also installed but were not in

service during the measurement. The power supply parameters are recorded for billet

heaters and at main incomer.



about 55 % loading i.e., frequency of 16.5 kHz. This billet heater is heating the iron rod

for forging. The rod piece average weight is 250 grams, the average time taken by three

61

billets is 14.48 sec. The average production rate is 186.54 kg/h. The average electrical



follows:
















d) The current total demand distortion (TDD) was measured in the range of 1.6 % to 9.8 %.

The current TDD is considered depending on the average current during the power


1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

ISC =1049.73*100*1.075/9.86 ≈ 11444 A

ISC/IL = 11444/41.56 ≈ 275


TDD must be less than 15.0 % as per the Table 10 but the actual measured value is 9.8

% and is lower than the limit.

62

4.1.8 Ismeet Forging


and connected load is 985.948 kW. At Ismeet Forging, two numbers one each of 300

kVA & 175 kVA billet heaters are installed and both billet heaters were in service to

heat the billets to the temperature in the range of 1150 to 1200 oC. The power supply

parameters are recorded for billet heaters and at main incomer.



about 75 % loading i.e., frequency of 750 Hz. This billet heater is heating the iron rod for

forging. The rod piece average weight is 4000 grams, the average time taken by three




follows:








three billets is 27.64 sec. The average production rate is 293.11 kg/h. The average







63
















1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

ISC =1049.73*100*1.075/9.86 ≈ 11550 A

ISC/IL = 11550/35.79 ≈ 323




4.1.9 Leela Forging


and connected load is 950 kW. At Leela Forging, two numbers of 150 kVA billet

heaters are installed and both billet heaters were in service to heat the billets to the



64








follows:











follows:


b) The voltage THD was in the range of 2.0 to 3.8 % and is normal








65










1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

ISC =1049.73*100*1.075/10.37 ≈ 10880 A

ISC/IL = 10880/23.57 ≈ 462




4.1.10 Nicks India Tools


and connected load is 1633.284 kW. At Nicks India Tools, one number of 175 kVA

billet heater is installed and was in service to heat the billets to the temperature in the

range of 1100 to 1200 oC. The power supply parameters are recorded for billet heaters




about 70 % loading i.e., frequency of 7.0 kHz. This billet heater is heating the iron rod




66


follows:



















1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

ISC =1049.73*100*1.075/10.0 ≈ 11284 A

ISC/IL = 11284/21.11 ≈ 535




67

4.1.11 JVR Forging


and connected load is 3536.7 kW. At JVR Forging, two numbers of 400 kVA, two

numbers of 200 kVA, one number of 700 kVA, one number of 500 kVA and one number

of 180 kVA billet heaters are installed. During the measurement, one number of 400

kVA and one number of 400 kVA billet heaters were in service to heat the billets to the




rating of billet heater 1 is 400 kVA. The design frequency is 1 kHz but the operating

was about 75 % loading i.e., frequency of 750 Hz. This billet heater is heating the iron

rod for forging. The rod piece average weight is 6300 grams, the average time taken by










was about 85 % loading i.e., frequency of 2550 Hz. This billet heater is heating the iron

rod for forging. The rod piece average weight is 3600 grams, the average time taken by







68



last one year (past data from energy bill). The peak demand factor is 60.54 to 73.03 %














1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

ISC =1049.73*100*1.075/9.77 ≈ 11550 A

ISC/IL = 11550/106.28 ≈ 109



11.4 % which is slightly lower than the limit because the percentage of non-linear load is

21.3 % which is lower side. But the TDD is varying widely at partial load.

4.1.12 Perfect Forging


and connected load is 1474.998 kW. At Perfect Forging, one number of 100 kVA and

one number of 250 kVA billet heaters are installed. During the measurement, only 100

69

kVA billet heater was in service to heat the billets to the temperature in the range of

1100 to 1200 oC. The power supply parameters are recorded for billet heaters and at

main incomer.



was about 50 % loading i.e., frequency of 5.0 kHz. This billet heater is heating the iron

rod (only front portion) for forging. Since only front portion is heating, it is difficult

compute the production in weight basis and thus it is considered as number of pieces

output as production rate. The average time taken for each piece is 18 sec. The

average electrical energy consumption for one piece is 0.22 kWh/piece. The Specific

energy consumption (SEC) is 0.22 kWh/piece. Observations on the power supply




















70

1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

ISC =1049.73*100*1.075/9.77 ≈ 11550 A

ISC/IL = 11550/79.73 ≈ 145



13.6 % which is slightly lower than the limit because the percentage of non-linear load is

3.2 % which is lower side. But the TDD is varying widely at partial load.

4.1.13 PS Industries


and connected load is 564.376 kW. At PS Industries, ten numbers of 10 kVA billet

heaters are installed. During the measurement, 9 billet heaters were in service to heat

the billets to the temperature in the range of 1100 to 1200 oC. The power supply



rating of billet heater 1 is 10 kVA. This billet heater is heating the iron rod (only front

portion) for forging. This billet heater is heating the iron rod for forging. The rod piece

average weight is 85 grams, the average time taken by each billet is 10.6 sec. The

average production rate is 28.87 kg/h. The average electrical energy consumption for

one hour is 11.34 kWh/h. The Specific energy consumption (SEC) is 0.39 kWh/kg of

steel. Observations on the power supply parameters are as follows:






71






























72





1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

ISC =1049.73*100*1.075/9.46 ≈ 11928 A

ISC/IL = 11928/14.47 ≈ 824



35.5 % which is on higher side. But the TDD is varying widely at partial load.

4.1.14 Global Export


and connected load is 324.799 kW. At Global Export, two numbers of 90 kVA billet

heaters are installed. During the measurement, one billet heater was in service to heat

the billets to the temperature in the range of 1150 to 1200 oC. The power supply





average weight is 500 grams, the average time taken by each billet is 5 sec. The

average production rate is 360 kg/h. The average electrical energy consumption for one

hour is 84.96 kWh/h. The Specific energy consumption (SEC) is 0.24 kWh/kg of





73
















1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

ISC =1049.73*100*1.075/9.35 ≈ 12069 A

ISC/IL = 12069/13.82 ≈ 873




4.1.15 Jai Parvati Forging


and connected load is 2394.744 kW. At Jai Parvati Forging, two numbers of 400 kVA

and one number of 1000 kVA billet heaters are installed. During the measurement, two

numbers of 400 kVA billet heaters were in service to heat the billets to the temperature

in the range of 1150 to 1160 oC. The power supply parameters are recorded for billet

heaters and at main incomer.

74



portion) for forging. The design frequency is 1 kHz but the operating was about 85 %

loading i.e., frequency of 850 Hz. This billet heater is heating the iron rod for forging.

The rod piece average weight is 9350 grams, the average time taken by each billet is

46.12 sec. The average production rate is 729.9 kg/h. The average electrical energy

consumption for one hour is 532.83 kWh/h. The Specific energy consumption (SEC)




















1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

75

ISC =1049.73*100*1.075/9.817 ≈ 11492 A

ISC/IL = 11492/29.7 ≈ 387




4.1.16 Samrat Forging


and connected load is 1995 kW. At Samrat Forging, one number of 300 kVA billet

heater is installed. During the measurement, one billet heater of 300 kVA was in service

to heat the billets to the temperature in the range of 1100 to 1200 oC. The power supply




portion) for forging. The design frequency is 1 kHz but the operating was about 80 %

loading i.e., frequency of 800 Hz. This billet heater is heating the iron rod for forging.

The rod piece average weight is 5600 grams, the average time taken by each billet is

35.55 sec. The average production rate is 567.17 kg/h. The average electrical energy

consumption for one hour is 197.54 kWh/h. The Specific energy consumption (SEC)











76










1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

ISC =1049.73*100*1.075/9.817 ≈ 11492 A

ISC/IL = 11492/26.12 ≈ 440





4.2.1 Presto Forging


and connected load is 198.29 kW. At Presto forging, two numbers of billet heaters of 20

kW are used for surface hardening of tools. The power supply parameters are recorded

for billet heaters and at main incomer.


rating of billet heater 1 is 20 kW (make: Bull Power Induction heater). This billet heater

is heating the front portion of tools. Since the heating takes place only at front portion of

the tool, the output cannot be taken in weight basis but can be taken on number of

pieces for particular time. The time taken for each tool is about 6 sec and the average

energy consumption for 20 pieces is 0.521 kWh. The specific energy consumption

77

(SEC) is 0.026 kWh/piece and SEC is very low. Observations on the power supply






rating of billet heater 2 is 20 kW (make: Bull Power Induction heater). This billet heater

is heating the front portion of tools. Since the heating takes place only at front portion of

the tool, the output cannot be taken in weight basis but can be taken on number of

pieces for particular time. The time taken for each tool is about 6 sec and the average

energy consumption for 14 pieces is 0.179 kWh. The specific energy consumption

(SEC) is 0.013 kWh/piece and SEC is very low. Observations on the power supply







contract demand is 220 kVA. The demand factor was varying between 26.3 % to 47.0 %

(based on monthly recorded demand past data form energy bill). The utility factor during

the power measurement was measured as 20.6 %. Figures 501 to 511 give the

variation of power supply parameters at Main incomer. Observations on the power




% and is slightly on higher side compared to limit prescribed by IEEE 519 standard. The

individual harmonics were less than prescribed limit of 5.0 %. As per the IEEE-519-1992

standard, the voltage THD be limited to a maximum value of 5.0 % with no individual

voltage harmonic to exceed 3.0 %, for the voltage up to 69 kV (refer Table 9).

78





1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

ISC =1049.73*100*1.075/10.32 ≈ 10935 A

ISC/IL = 10935/1.33 ≈ 8222


than 20.0 % as per the Table 10 but the actual measured value is 61.8 % which is on

higher side. But the TDD is varying widely at partial load.

4.2.2 Nakul Gupta Automobile Parts


and connected load is 249.92 kW. At this shop, machining of automobile parts is being

carried out and one number of surface hardening induction heater of 50 kW is installed.

The temperature maintained is about 450 oC. The power supply parameters are


Figures 512 to 518 give the variation of power supply parameters at surface hardening

induction heater. The rating of surface hardening induction heater is 50 kW. This billet

heater is heating the centre portion of automobile parts. Since the heating takes place

only at centre portion of the automobile parts, the output cannot be taken in weight

basis but can be taken on number of pieces for particular time. The time taken for each

piece is about 15 sec and the average energy consumption for 20 pieces is 2.517 kWh.

The specific energy consumption (SEC) is 0.126 kWh/piece and SEC is very low.





79



contract demand is 220 kVA. The demand factor for total load was varying between

50.1 % to 68.60 % (based on monthly recorded demand past data form energy bill). The

inductive surface heater demand factor is 28.6 %. The total demand factor during the

power measurement was measured as 106.6 %. Figures 521 to 531 give the variation

of power supply parameters at Main incomer. Observations on the power supply




% and is slightly on higher side compared to limit prescribed by IEEE 519 standard. The








1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

ISC =1049.73*100*1.075/10.32 ≈ 10935 A

ISC/IL = 10935/6.65 ≈ 1644




4.2.3 Rama Steel


and connected load is 200.248 kW. At Rama steel, two numbers of two phase metal

80

gathering heaters of 35 kW are used to heat the metal rod and forge to make tools

which are used for tightening of bolts of lorry wheels. The principle of working of this

metal gathering is shorting the secondary of transformer through the metal rod which is

heated and pressed against the metal. The metal rod will contrast at front with red hot

which will be forged in forging machine to get the required shape. The power supply

parameters are recorded for metal gathering heaters and at main incomer.

Figures 532 to 538 give the variation of power supply parameters at metal gathering

heater 1. The rating of heater 1 is 35 kW (make: Sunrise heater). This heater is heating

the front portion of tools. Since the heating takes place only at front portion of the tool,

the output cannot be taken in weight basis but can be taken on number of pieces for

particular time. The time taken for each tool is about 2 minutes and the average energy

consumption for 12 pieces is 3.472 kWh. The specific energy consumption (SEC) is

0.29 kWh/piece and SEC is less. Observations on the power supply parameters are as

follows:

a) The voltage at heater was varying widely due to non-linear loading.

b) The voltage THD was in the range of 1.1 % - 3.8 % and is normal.


Figures 539 to 545 give the variation of power supply parameters at metal gathering

heater 2. The rating of heater 2 is 35 kW (make: Sunrise heater). This heater is heating

the front portion of tools. Since the heating takes place only at front portion of the tool,

the output can not be taken in weight basis but can be taken on number of pieces for

particular time. The time taken for each tool is about 2 minutes and the average energy

consumption for 13 pieces is 7.028 kWh. The specific energy consumption (SEC) is

0.54 kWh/piece and SEC is less. Observations on the power supply parameters are as

follows:

a) The voltage at heater was varying widely due to non-linear loading.

b) The voltage THD was in the range of 1.2 % - 4.0 % and is normal.


81



contract demand is 196 kVA. The demand factor was varying between 27.97 % to 64.16

% (based on monthly recorded demand past data form energy bill). The utility factor

during the power measurement was measured as 56.57 %. Figures 548 to 558 give the



a) The voltage at inlet was varying between 10.42 to 10.83 kV and is slightly on

lower side.


% and is lower compared limit prescribed by IEEE 519 standard. The individual

harmonics were less than prescribed limit of 5.0 %. As per the IEEE-519-1992







1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

ISC =1049.73*100*1.075/10.32 ≈ 10935 A

ISC/IL = 10935/3.46 ≈ 3160






and connected load is 6000 kW. At Happy forging, two numbers of 225 kVA and one

number of 200 kVA induction surface hardening machines are installed. The

82

temperature maintained is about 950 – 1150 oC. The power supply parameters are



induction heater 1. The rating of surface hardening induction heater 1 is 225 kVA. This

hardening is heating the centre portion of automobile parts. Since the heating takes

place only at centre portion of the automobile parts, the output cannot be taken in

weight basis but can be taken on number of pieces for particular time. The time taken

for each piece is about 17 sec and the average energy consumption for each piece is

0.36 kWh. The specific energy consumption (SEC) is 0.36 kWh/piece and SEC is

very low. Observations on the power supply parameters are as follows:


b) The voltage THD was in the range of 1.9 % - 4.7 % and is normal




hardening is heating the centre portion of automobile parts. Since the heating takes





very low. Observations on the power supply parameters are as follows:






contract demand is 5250 kVA. The demand factor was varying between 21.09 to 28.2 %

(based on monthly recorded demand past data form energy bill). The utility factor during

83

the power measurement was measured as 28.31 %. Figures 577 to 588 give the





% and is lower compared limit prescribed by IEEE 519 standard. The individual





d) The current total demand distortion (TDD) was measured in the range of 2.0 % to 8.8 %.

The current TDD is considered depending on the average current during the power


1.075% Im

FLSC

II X

pedance voltage= A

Axx

I FL 3.26240.66*3

31000100==

ISC =2624.3*100*1.075/14.11 ≈ 19994 A

ISC/IL = 19994/10.51 ≈ 1902


than 20.0 % as per the Table 10 but the actual measured value is 8.8 % and is on lower

side.

4.2.5 GNA Enterprises



carried out. One number of 350 kVA, five numbers of 250 kVA, three numbers of 125

kVA and two numbers of 200 kVA induction surface hardening machines are installed.

Apart from induction hardening machines one 150 kVA motor-generator set (M-G set)

i.e., rotary motor set is also installed for surface hardening. During measurement, one

each of 100 kVA & 320 kVA were in service. The temperature maintained is about 950 –

84

1150 oC. The power supply parameters are recorded for billet heaters and at main

incomer.



billet heater is heating the centre portion of automobile parts. Since the heating takes





high. Observations on the power supply parameters are as follows:











low. Observations on the power supply parameters are as follows:




Figures 607 to 613 give the variation of power supply parameters at rotary machine.

The rating of rotary machine is 150 kVA. This billet heater is heating the centre portion

of automobile parts. Since the heating takes place only at centre portion of the

automobile parts, the output cannot be taken in weight basis but can be taken on

85

number of pieces for particular time. The time taken for each piece is about 320 sec and

the average energy consumption for each piece is 15.75 kWh. The specific energy

consumption (SEC) is 15.75 kWh/piece and SEC is high. Observations on the power








59.02 % to 91.59 % (based on monthly recorded demand past data form energy bill).

The total demand factor during the power measurement was measured as 86.89 %.



a) The voltage at inlet was varying between 10.41 to 10.8 kV and is slightly lower.


% and is on lower side compared to limit prescribed by IEEE 519 standard. The








1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

ISC =1049.73*100*1.075/9.98 ≈ 11307 A

ISC/IL = 11307/49.11 ≈ 230

86




4.2.6 GNA Udyog Ltd.,



carried out. One number of 320 kVA, two numbers of 100 kVA, three numbers of 50

kVA, one number of 40 kVA and four numbers of 30 kVA surface hardening machines

are installed. During measurement, one each of 100 kVA & 320 kVA were in service.

The temperature maintained is about 950 – 1150 oC. The power supply parameters are








2.0 kWh. The specific energy consumption (SEC) is 2.0 kWh/piece and SEC is low.











87

2.0 kWh. The specific energy consumption (SEC) is 2.0 kWh/piece and SEC is low.












a) The voltage at inlet was varying between 10.66 to 10.90 kV and is slightly lower.










1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

ISC =1049.73*100*1.075/9.01 ≈ 12524 A

ISC/IL = 12524/40.88 ≈ 306



11.1 % and is on lower side.

88

4.3 Induction Furnaces

4.3.1 Garg Furnaces


and connected load is 7599 kW. At this factory, two numbers of scrap melting furnaces

of 3 tonne and 6 tonne capacity are installed. The power supply to these furnaces is fed

at 11 kV. During the power measurement only one furnace of 6 tonne was in service.

The temperature maintained is about 1450 oC. The power supply parameters are

recorded for induction furnace and at main incomer.

Figures 662 to 668 give the variation of power supply parameters at induction furnace.

The average cycle time for melting of scrap is about 2 to 3 hours and vary with the

grade. The energy consumption for one cycle of melting of 6 tonne of steel is measured

as 4,895.4 kWh. The specific energy consumption (SEC) is 815.9 kWh/t of steel.


a) The voltage at furnace was varying widely due to non-linear loading.










a) The voltage at inlet was varying between 64.56 to 69.30 kV and is slightly on

higher side.




89




e) The current total demand distortion (TDD) was measured in the range of 2.5 % to 41.8



1.075% Im

FLSC

II X

pedance voltage= A

Axx

I FL 32.26240.66*3

10003100==

ISC =2624.32*100*1.075/15.02 ≈ 18783 A

ISC/IL = 18783/21.75 ≈ 864




4.3.2 Raj Furnaces


and connected load is 299.914 kW. At this factory, one number of scrap melting furnace

of 300 kg capacity is installed. The power supply to this furnaces is fed at 11 kV. The

temperature maintained is about 1400 oC. The power supply parameters are recorded

at main incomer because only furnace load was available & no other loads were in

service.


The average cycle time for melting of scrap is about 1 hour 15 minutes to 1 hour 30

minutes and vary with the grade. The energy consumption for one cycle of melting of

300 kg of steel is measured as 263.94 kWh. The specific energy consumption (SEC)

is 879.8 kWh/t of steel. Observations on the power supply parameters are as follows:



90















1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

ISC =1049.73*100*1.075/10.32 ≈ 10935 A

ISC/IL = 10935/14.43 ≈ 758




4.3.3 Basant Metal Works


and connected load is 709.891 kW. At this factory, one number of scrap melting furnace

of 500 kg is installed. The power supply to this furnace is fed at 11 kV. The temperature

maintained is about 1550 oC. The power supply parameters are recorded for induction

furnace and at main incomer.

91



minutes and vary with the grade. The energy consumption for one cycle of melting of

500 kg of steel is measured as 450.778 kWh. The specific energy consumption

(SEC) is 901.56 kWh/t of steel. Observations on the power supply parameters are as

follows:


b) The voltage THD was in the range of 3.3 to 11.8 % and is on higher side.


Figures 702and 703 give the variation of recorded demand and energy consumption for









% and is slightly higher side compared to limit prescribed by IEEE 519 standard. The








1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

ISC =1049.73*100*1.075/10.32 ≈ 10935 A

92

ISC/IL = 10935/22.66 ≈ 483




4.3.4 Nidhi Steel Industries


and connected load is 2250 kW. At this factory, one number of scrap melting furnace of

4 tonne is installed. The power supply to this furnace is fed at 11 kV. The temperature

maintained is about 1550 oC. The power supply parameters are recorded for induction

furnace and at main incomer.



minutes and vary with the grade. The energy consumption for one cycle of melting of 4

tonne of steel is measured as 2960.77 kWh. The specific energy consumption (SEC)

is 740.19 kWh/t of steel. Observations on the power supply parameters are as follows:













% and is lower compared to limit prescribed by IEEE 519 standard. The individual

93





e) The current total demand distortion (TDD) was measured in the range of 2.6 % to 78.2



1.075% Im

FLSC

II X

pedance voltage= A

Ax

I FL 73.10490.11*3

100020==

ISC =1049.73*100*1.075/10.32 ≈ 10935 A

ISC/IL = 10935/115.61 ≈ 95

The ISC/IL ratio at peak power is 95 which is more than 50 and less than 100. The TDD

must be less than 12.0 % as per the Table 10 but the actual measured value is 78.2 %

which is on higher side. But the TDD is varying widely at partial load.

4.3.5 Varun Steel Casting


and connected load is 5999 kW. At this factory, two numbers of scrap melting furnaces

of 4 tonne are installed. During power measurement one furnace was in service. The

power supply to these furnaces is fed at 11 kV. The temperature maintained is about

1600 oC. The power supply parameters are recorded for induction furnace and at main

incomer.


The average cycle time for melting of scrap is about 1 hour 30 minutes to 2 hours and

vary with the grade. The energy consumption for one cycle of melting of 4 tonne of steel

is measured as 3131.2 kWh. The specific energy consumption (SEC) is 782.8 kWh/t

of steel. Observations on the power supply parameters are as follows:



94
















f) The current total demand distortion (TDD) was measured in the range of 6.1 % to 23.4



1.075% Im

FLSC

II X

pedance voltage= A

Axx

I FL 32.26240.66*3

10003100==

ISC =2624.32*100*1.075/15.02 ≈ 18783 A

ISC/IL = 18783/22.22 ≈ 845

The ISC/IL ratio at peak power is 95 which is more than 100 and less than 1000. The TDD

must be less than 15.0 % as per the Table 10 but the actual measured value is 23.4 %

which is on higher side. But the TDD is varying widely at partial load.

4.4 Arc Furnace: Upper India Steel Industries


and connected load is 29446.42 kW. At this factory, two numbers of Arc furnaces of 25

95

tonne capacity and one number of Laddle furnace of 25 tonne capacity are installed.

During power measurement both arc furnaces and one ladle furnace were in service.

The power supply to these furnaces is fed at 11 kV. The temperature maintained is

about 1550 – 1650 oC. The power supply parameters are recorded for these furnaces


Figures 755 to 761 give the variation of power supply parameters at Arc furnace 1. The

average cycle time for melting is about 2 hour 30 minutes and varies with the grade.

The energy consumption for one cycle of melting of 25 tonne is measured as 14,577

kWh. The specific energy consumption (SEC) is 583.08 kWh/t of steel.





Figures 762 to 768 give the variation of power supply parameters at Arc furnace 2. The

average cycle time for melting is about 2 hour 30 minutes and varies with the grade.

The energy consumption for one cycle of melting of 25 tonne is measured as 9220.4

kWh. The specific energy consumption (SEC) is 368.82 kWh/t of steel.





Figures 768 to 774 give the variation of power supply parameters at Laddle furnace.

The average cycle time for melting is about 1 hour 30 minutes and varies with the

grade. The energy consumption for one cycle of melting of 25 tonne of steel is

measured as 2,145.6 kWh. The specific energy consumption (SEC) is 85.82 kWh/t

of steel. Observations on the power supply parameters are as follows:




96



contract demand is 20,000 kVA. The demand factor for total load was varying between

70.05 % to 79.84 % (based on monthly recorded demand past data from energy bill).














1.075% Im

FLSC

II X

pedance voltage= A

Axx

I FL 32.26240.66*3

10003100==

ISC =2624.32*100*1.075/15.02 ≈ 18783 A

ISC/IL = 18783/31.41 ≈ 598




5.0 CONCLUSIONS

The main conclusions from the study are as follows:

i) Induction billet heaters and induction melting furnaces works on the principle of

97

high frequency variable AC supply. These furnaces inject pollutants in to the

grid.

ii) The harmonic currents at point of common coupling at industry create voltage

fluctuation and voltage flicker in the grid which are harmful to human eye. These

voltage flickers will affect the other customers which are fed from the feeder.

iii) The non-linear loading will reduce the capacity of distribution system and cause

more energy losses.

iv) To overcome the power pollution problem in grid, the utility had to provide

enough short circuit level in the grid to absorb the pollutants in the network.

v) The specific energy consumption of billet induction heaters (SEC: 0.24 to 0.83

kWh/kg) are less compared to induction melting furnace (SEC: 0.74 to 0.902

kWh/kg) because melting furnace need higher energy to melt the scrap

(temperature maintained in the range of 1400 to 1650 oC) but in the billet heater

the metal will become red hot (temperature maintained in the range of 1150 to

1250 oC).

vi) The presence of harmonics in the system reduces the capacity of distribution

capacity of utilities i.e., transformers, overhead lines, cables, circuit breakers,

etc.

vii) Since the concern is with respect to power or demand not with energy

parameters, therefore, the demand factor will not pay a major role. The demand

factors for both billet heaters and induction melting furnaces are having a same

nature except surface hardening induction machines (smaller capacity).

viii) It is very difficult to differentiate billet heater and induction melting furnace as far

as power quality and power supply parameters are concerned but SEC will be

less for billet heaters compared to induction melting furnace. But the concern is

with power or demand and not with energy consumption.

ix) The voltage fluctuations depend on the rating of bulk non-linear load.

x) The Billet heaters and surface hardening machines can be considered as power



with respect to power quality parameters for billet heaters, surface hardening

98

machines & induction furnaces are same. The impact of power quality

parameters like voltage dip, voltage flickers, voltage & current waveform

distortions, harmonics, capacity loss of utility distribution system, demand factor,

energy loss in distribution system, energy intensive factor, etc, are all same.

Only the specific energy consumption for induction furnaces is slightly higher

compared to billet heaters due to change of state of material from solid to liquid

& higher degree of melting temperature.

xi) The non-linear load is the load where the current is not proportional to voltage


induction billet heaters, induction surface hardening machines and induction




Documents

Final PSPCL report part 1