REPORT: A vocational training at:

Kharsia road, Raigarh, Chhattisgarh 496001

25

Acknowledgement:

I am grateful to Jindal Steel and Power Limited to give me such an opportunity to visit inside the plant and earning practical knowledge about the Electrical system and process.

I am very much thankful to the respected sir, Mr. Rajesh Agrawal (Head of the department, EPS), Mr. M.V. Sudhakar sir (Manager, MRSS-2), Mr. Karamchand Dewangan sir and all the concerned officers to allow for the visit & guide me to make this visiting valuable.

Kishan GabelB.Tech. 2nd year

Electrical, NIT Raipur

Jindal Steel and Power Limited (JSPL) is an Indian steel and energy company based in New-Delhi with

turnover of approx. US$ 3.3 billion. JSPL is a leading player in steel, power, mining, oil and gas and infrastructure in India. The company produces steel and power through backward integration from its own captive coal and iron-ore mines.

JSPL has 6 major subsidiaries:

Jindal Power Limited which operates JINDAL TAMNAR POWER PLANT a 1000 MW (4x250 MW) coal-based thermal power plant in Raigarh in state of Chhattisgarh. This plant is fully functional.

Jindal Shadeed Iron and Steel, Oman Jindal Steel Bolivia Jindal Steel and Power Mauritius Jindal Africa Investments Skyhigh Overseas

#LAYOUT AND CONNECTION DIAGRAM OF ELECTRICAL POWER SYSTEM FOR ALL INTERCONNECTED JINDAL PLANTS:

About Main Receiving Substation (MRSS):

JPL4X250 MW

DCPP4X135 MW CSEB

MRSS-1MRSS-3

MRSS-4

NSPLMRSS-2

This is mainly a system arranged at generating or distributing areas to control and protect the electric power being transmitted through transmission lines. In other words, this helps to maintain the balanced power flow and outgoing to any feeder.

These substations are arranged also to protect the equipments installed at the line or to provide isolation to a specific line in faulty conditions, such as short circuit or ground faults.

#Components of a substation:

Incoming line Main bus Isolator Potential transformer Current transformer Circuit breaker Bushings Insulators Power Transformer Outgoing feeders Conductor & cables Gantry structures

Incoming lines (or incomers)

These are mainly transmission lines which are used to charge the main bus situated at any substation; or it may be any cables or conductors. All the bays or divided supplies are charged by connecting it to the main bus which is charged by the incomer.

Main busBus in a substation works like a main charging spot for all the feeders and outgoing bays, the outgoings in turn charges another bus of any other substations.

IsolatorThere are two types of isolators:

1. Bus isolator2. Line isolator

Bus isolator isolates the line to main bus.In case of more than one buses are there then bus isolator helps us to choose from which we want the line to be charged.

Line isolator isolates the buses from the main lines of transmission. This completely removes the connection of any bus to be charged.

Potential transformer (voltage transformer, VT)

This is a type of measuring instrument which uses the principle of operation of transformer to measure the potential of any line in terms of phase to ground voltage.

Connection diagram:

Current transformer (CT)This is also a type of measuring instrument in which high current is measured in terms of low value. This is made of a step-up transformer followed by a low range ammeter.

Circuit breaker (CB)

There are three categories for circuit breakers:

1.Low current breaker

2.Medium current breaker

3.High current breaker

Also there are many types of circuit breakers:

1. Miniature circuit breaker(MCB)2. Moulded case circuit breaker(MCCB)3. Vacuum circuit breaker(VCB)4. Air circuit breaker(ACB)5. SF6 circuit breaker6. CO2 circuit breaker

Circuit breakers work as a switch to open or close the line in which this is installed. Thus it provides protection in case of any fault in the line by simply opening the connection, which is called “Tripping”.

While isolator does the same work as circuit breaker but the main difference is the mode of operation of the two equipments. Circuit breakers are specific to operate at loaded condition while isolator can’t be used on loading, it can only be used in off-load or open circuited condition.

BushingsBushings are nothing but the insulation provided between the body and any of the equipment. These are made up of Porcelain. In transformers two types of bushings are provided; namely HV bushings and

LV bushing. HV bushings are provided to connect the internal windings of the transformer to the outer conductor without having body contact to the transformer.

InsulatorsInsulators are the non conducting medium made of insulating material. The resistance offered by this material is very much higher than the conductors; therefore this is used to restrict the current to the conductors itself. Work of insulators is to mechanically support the conductors with the gantries.

Power transformerTransformers which are used to transfer power at one voltage level to another voltage level throughout same frequency.

Power transformer 100/120 MVA on 220kV yard

Nameplate rating for 100/120MVA power transformer:

Cooling type: oil natural

Outgoing feeder:The output to a substation is called a feeder. Feeder means the component which feeds power to a specific system, it maybe a furnace or a motor driving system.

Conductors and cables:Mainly two types of current carriers are used in substations. One is the bare conductor while the other is through power cable. Bare conductors are used where more height can be

given to the conductor and no need to insulate the current carrier while cables are used for relatively low voltage power transmission and wherever transmission

incomer lines

power transformers

Feeders

medium is underground or under watered. Power cables provide insulation as well as protection to the conductor whereas bare conductors don’t have the same.

Types of Conductors:1.ACSR (Aluminium conductor steel

reinforced)

These are manly used for long transmission lines because the steel used provides more strength to the Aluminium which is the main media for current to flow through.

2.AAAC (All Aluminium alloy conductor)

These conductors are nothing but strands of Aluminium alloy, which are arranged layer wise. These have lower mechanical strength than ACSR conductors but current conducting

media has higher area of cross section. Therefore this provides relatively low resistance than ACSR conductors at

the cost of mechanical strength.

3.AAC (Aluminium alloy conductor)

It constitutes in parts; one part contains the alloys of Aluminium while another part contains Aluminium in metal form. These are not generally used now-a-days in substations. Basically these conductors are for lower strength transmission and distribution.

Gantry structure:The metallic supporting structures which are used to

support the conductors and to provide base for installation of various types of equipments like CT, PT and LA, are called gantry. Generally gantries are made up of steel and are pre-fabricated by its provider company. All the gantries used inside any of the substations are also provided with alternative earthings.

About ETL(electro technical lab)All the equipments must be treated so healthily as to maintain proper working and lossless operation. In order to maintain these operations regular and standardised testing is required. In ETL lab, testing of various components of transformers, breakers and other equipments is done under expertise surveillance. On field as well as sample testing is done in this laboratory. Some of the tests are named as given below:

transformer testing

AC

magnetic balance

magnetizing current

turns ratio

DC

winding resistance

polarisation index

insulation resistance

AC testing: Magnetic balance test

The core of the transformer is tested for the distribution of the flux to be uniform throughout the core for all the primary and secondary

windings. Magnetising current test

After applying the AC voltage at no load, the primary and secondary of the transformer must have the at most current value. The core magnetising current is generally 2-3% of the rated current.

Turns ratio testAC voltage of any definite magnitude is applied to any of the primary or secondary of the transformer then the induced open circuit voltage of the other winding is tested whether it is according to the ratio of the nameplate ratings of the transformer or not. For a 220kV/33kV transformer this ratio is found to be 6.667.

DC testing:

Winding resistance testThe transformers windings are tested whether the resistance is in the proper limit to a specific value or not. Main purpose of this testing is to minimize & maintain the Copper losses occurring inside the transformer. The readings of the windings

resistance is found of the order of milli-ohms (mΩ). Insulation resistance test

The windings are tested for the following faults which may occur: phase-to-phase short circuit, phase-to-ground short circuit and any other insulation failure inside the transformer body is maintained under this. The insulation resistance is measured with Megger up to one minute.

Polarisation index testBoth Insulation Resistance Test (IR) and Polarisation Index Test (PI) are conducted on HV machine to determine service condition of the insulation. In HV machines windings are likely to be affected by moisture and contamination. IP test is conducted specially to determine the dryness and cleanliness of the winding insulation.

TRW (Transformer Repair Workshop)In this workshop various components of the substation are

repaired under the guidance of experts. Various transformers

like power transformers, current transformer, potential

transformers etc. are repaired and their proper operation is

maintained.

Transformer oil tankers

Rectifier & Battery bank arrangement DC power supply is must to run some basic control

equipments inside as well as outside any power system.

Therefore, an alternate source of DC should be arranged.

When AC power is available to us, we can get desired

amount of DC supply by rectifying the AC power through step

down transformers and thyristors.

In case of AC failure, we use battery banks to provide

uninterrupted power supply.

Battery-banks A battery bank is

nothing but the series

connection of multiple

similar type batteries.

The numbers of

batteries are considered

according to the ratings

of a single cell as well

as the desired DC voltage level.

Control Room

The main control and monitoring is done at indoor arrangement.

Basically this room has

panels installed inside the

room itself. The panels

have their input and

output communications

through incomers and

command lines which are connected to the main bus of the

control panel.

Control panels are available at indoor of any substation for

each individual voltage bus, means separately for 220kV and

33kV also ACDB and DCDB.

Cooling towers

Cooling towers are installed at the substation to exchange heat

through heat exchanger for SVC yard. Pumping by Induction

motors are done in order to maintain regular cycling of water

and the heat exchanger.

(Schematic diagram for cooling tower)

SAFETY: Must wear helmets to protect your head from any fallen

object or to pass through any low clearance door.

You should wear good standardised safety shoes in order

to protect your legs from any hard injury.

Wear glasses to protect your eyes.

Avoid loose cloths.

Don’t make large steps while walking through yard.

THANK YOU FOR READING AND COOPERATION.