22861869 Summer Training Report

7/31/2019 22861869 Summer Training Report

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2/96

ELECTONIC AND INSTRUMENTION DEPT.

Compiled & Submitted By:-

ABHAS GUPTA

(Roll No.:- 0902932001

B.Tech (EIE)- VI semester


3/96

ACKNOWLEDGEMENT

We are highly thankful to B.H.E.L. engineers and technical staff

for providing us vital and valuable information

about the differentfacts of an industrial

management system.We express our gratitude to Human Resource

and Developmentdepartment for giving us a chance to feel the

industrial environmentand its working in B.H.E.L. and we are thankful to Mr. M.K.Nagaich,

Giving his precious time and help us in on CNC under whose kind

Supervision we accomplished our project we are thankful to Mr VIJAY

VERMA for his kind support.

ABHAS GUPTA

(B.Tech (EIE), KIET, GHAZIABAD)


4/96

PREFACE

At very outset of the prologue it becomes

imperative to insist thatvocational training is an integral part of engineering curriculum.

Training allows us to gain an insight into the

practical aspects of thevarious topics, with which we come across while

pursuing our B.Techi.e. vocational training gives us practical

implementation of varioustopics we already have learned and will

learn in near future.Vocational training always emphasizes on logic

and commonsenseinstead of theoretical

aspects of subject.On my part, I pursued four weeks training at

B.H.E.L. Jhansi. Thetraining involved a study of various departments of

the organizationas per the time logically scheduled and well

planned given to us.The rotation in various departments was

necessary in order to getan overall idea about the working of

the organization.

A

B

H

A

S

G

U

P

T

A

(B.Tech (EIE), KIET,

GHAZIABAD)


5/96

BHARAT HEAVY

ELECTRICALS LIMITED

In the post independence era when India

was moving towardsindustrialization, the thrust by the government

was in the core sector.

Wi

t

h

t

h

i

s

o

b

j

e

c

ti

v

e

BHARAT HEAVYELECTRICALS LIMITED was setupin Bhopal in August 1956, with a view to

reach self sufficiency inindustrial products and power equipments. This

plan was setup undercollaboratio

n of M/s.

AEJ, U.K.Now more plants were setup at Tiruchy,

Hyderabad and Haridwarwith Czechoslovakian and Soviet Union

assistance in May 1956, Dec.1965, and Jan. 1967 respectively. Today

B.H.E.L. has become thelargest engineering plant employing

approximately 72000employees. Its headquarters

are located at Delhi.B.H.E.L. is the largest engineering and

manufacturing enterprisein India in the energy/infrastructure sector,

today. B.H.E.L. wasestablished more than forty years ago

ushering in the indigenousheavy electrical equipments industry in India a

dream that has beenmore than realized with a well-

recognized track record ofperformance. It has been earning profits since

1971-72 and payingdivid

ends

since

1976-

77.

B.H.E.L. manufactures over 180

products under thirty major

product groups and caters to core sectors of theIndian Economy viz.,Power Generation and Transmission,

Industry, Transportation,Telecommunication, Renewable Energy, etc.

The wide network ofB.H.E.L.s fourteen manufacturing

divisions, four power sector


6/96

regional centers, over hundred project sites,

eight service centersand eighteen regional offices, enables the

company to promptlyserve its customers and provide them

with suitable productsefficiently and at

competitive

prices.The quality and reliability of its products is

due to the emphasis ondesign, engineering and manufacturing to

international standards byacquiring and adapting some of the best

technologies from leadingcompanies in the world, together with

technologies developed in itso

w

n

R

&

D

c

e

n

te

r

s

.

B.H.E.L. has acquired certifications to

Quality ManagementSystems- ISO 9001, Environmental Management

Systems-ISO 14001and Occupational Health and Safety

Management Systems-OHSAS18001 and has also adopted the

concepts of Total QualityMana

geme

nt. B.H.E.L. has installed equipment for over90,000 MW of powergeneration- for Utilities, Captive, and Industrial

users. It supplied over2,25,000 MVA transformer capacity and

sustained equipmentoperating in transmission and distribution

network up to 400 KV- AC& DC.

It supplied over 25,000 motors with

Drive Control System topower projects, petrochemicals, refineries, steel,

aluminum, fertilizer,cement plants, etc. It also supplied traction

electrics and AC/DC locosto power over 12,000 Km railway network.

Supplied over one millionvalves to power plants

and other industries.

B.H.E.L.s operations are organized

around three businesssectors, namely Power Industry

including Transmission,


7/96

Transportation, Telecommunication and

Renewable Energy andOverseas Business. This enables B.H.E.L. to

have a strong customerorientation, to be sensitive to his needs and

respond quickly to thech

an

ge

s

in

thema

rke

t.

B.H.E.L.s vision is to become a

world class engineeringenterprise, committed to enhance stakeholder

value. The company isstriving to give shape to its aspirations and fulfill

the expectations as aN

a

v

r

a

t

n

a

C

o

m

p

an

y

.

The greatest strength of B.H.E.L. is

its highly skilled andcommitted 44,000 employees. Every

employee is given an equalopportunity to develop himself and improve his

position. Continuoustraining and retaining, career planning, a

positive work culture andparticipative style of management have

engendered development ofa committed and motivated work force

leading to enhanced

productivity andhigher levels of

quality.


8/96

VISION, MISSION AND VALUES

OF B.H.E.L.

VISION:

A world class engineering enterprise

committed to enhancings

t

a

k

e

h

o

l

d

e

r

va

l

u

e

.

Mission

:To be an Indian Multinational Engineering

Enterprise providing totalbusiness solution through quality products,

system and services in thefields of energy, industry, transportation,

infrastructure and otherpotential

area

s.

VALU

ES:Zeal to

Excel Zest

for

change.

Integrity and

fairness in all

matters.Respect for dignity and potential

of every individual.Strict

adherence tocommitments.Ensur

e

speed

of

respon

se.

Faster learning,

teamwork and

creativity.Loyalty and

Pride in the

Company.


9/96


10/96

MANUFACTURING

UNITS OF B.H.E.L.

First

Gene

ration

Units

BHOPAL

Heavy Electrical Plant

HARDWAR HeavyElectrical Equipment PlantHYDERABAD Heavy Electrical

Power Equipment PlantTIRUCHY High

Pressure Boiler Plant

Second

Generat

ion

UnitsJHANSI Transformer

and Locomotive PlantHARDIWAR Central

Foundry and Forge PlantTIRUCHY

Seamless Steel Tube Plant

Unit Through

Acquisition and

MergerBANGALORE

Electronic DivisionElectr

o

Porcel

ain

Divisi

on

New

Manufac

turing

UnitsRANIPAT

Boiler Auxiliaries Plant

JAGDISHPURInsulator PlantRUDRAPUR Component

and Fabrication PlantBANGALORE

Industrial System Group


11/96

Focus

To build a high degree of customer

confidence by providingincreased value for his money through

international standards ofproduct performance

superior customer service.

Pe

op

le

Or

ie

nt

ati

on

To enable each employee to achieve his

potential, improve hiscapabilities, perceive his role and

responsibilities and participateand contribute to the growth and success of the

company, to invest inhuman resources continuously and be

alive to their needs.

Tech

nolo

gy To achieve technologicalexcellence in operations bydevelopment of indigenous technologies and

efficient absorption andprovide competitive

advantage to the company.

Image

To fulfill the expectations which

stakeholders like government asowner, employees, customers and the country

at large have fromB.H.E.L.


12/96

THE PRODUCT PROFILE OF

B.H.E.L., JHANSI

S.No.

Products

Specifications1. Power Transformer Up to 220

KVA class 250 MVA2. Special

Transformer Up to

110 KVA3. ESP

transformer

1000 KVA4. Fright Loco Transformer 3900-5400

KVA & 6500 KVA (3 Phase)

5. ACEMU Transformer Up to 1000

KVA 25 KV (single phase)

6. Dry Type

Transformer Up to 3150

KVA7. Bus Duct Up to

15.75 KVA (Generating voltage)

8. Instrument Transformer VT and

CT up to 220 KVA9.

D

ie

se

l

E

n

gi

ne

Up

to

260

0

HP

Loco

motive10. AC/DC Locomotive Up to 5000 HP

(25 KV AC/1500v DC)

11. Well

Wagon

200

Tones

12.

Over

Head

Equipment

cum

Test Car

13.

Dynamic

Track

Stabilizer

14.

Ballast

Cleaning

Machine


13/96


14/96

14.

1990-

91

Successful Design and

Manufacturing of 400 HP 3A

xe

l

Di

es

el

C

CI

15.

1991-

92

Manufacture of First 2600

HP Diesel for NTPC

16.

1992-

93

Successful Design

and Development

of5000 HP Thruster

ControlLocomotive17.

1993-

94

Unit has been

Awarded ISO-

19001Certificate

for Quality

Systems18.

1994-

95

240 MVA Power Transformer

Produced First Time

19.

1995-

96

AC/DC

Locomotives first

time in India20.

1996-

97

Hundredth

Locomotive

Manufactured21.

1997-

98

250 MVA

Transformer

Produced First22.1998-

99

Developed Over HeadEquipment cum Test Car

23.

1999-

00

Diesel

Hydra

ulic

Shunti

ng


15/96

ROTA

TIONREP

OR

T


16/96

FABRICATION

(BAY-0, 1, 2)

Fabrication shop is the shop which deals with

the manufacturing oftransformer and locomotive components such

as Tanks, Plates, andNuts and Bolts. Fabrication shop is

divided into three parts-

BAY-0

BAY-1

BAY-2

BAY-

0This is the preparation shop, in this shop;

we cut the differentcomponents of the different

materials as per the drawingrequirements. Different

processing m/s in thisBAY is as

follo

ws CUT

TIN

G

MAC

HIN

E

a) CNC FLAME

CUTTING

MACHINEBy the use of this machine any shape can be

obtained up to 2.5m toX7m.

Maker

ESAB

Germany

made

Flame

Oxy-

Acetylene

Flame

Feeding Language ESSI

Format, ESC FormatCapacity

3.15mm to

300mm


17/96

b) A

c

c

u

r

a

c

y

0

.

1

m

m

Cutt

ing

Too

l

Cop

per

Material

s to cut

Mild

steel

c) P

A

N

T

OG

R

A

P

H

d) P

U

G

C

U

T

T

I

N

G

e) SHEARI

NGThis machine is used for metal sheet. Cutting

range is 2mm to 6 mm.Suitable materials for use are Al,

Standard steel and Cu.

BEN

DIN

G

MAC

HIN

E

Principl

e

Hydr

aulica

lly

operated

Pressure Gauge is used to read out the

pressure applied. Stoppingmechanism is used by screw to prevent thecollapsing the ram bladewith

bending

grooves

(Die).

ROL

LING

MAC

HINEThis machine is used for decreasing the roll

thickness. The rollermaterial used is

High Carbon

Steel.It is having the two rollers and one bending

roller. In this machine,gears are used for speed reduction of the rollers

to give uniform andbetter thickness and good surface finish.

Wedge type metal piece isused (Manually operated) for changing the gap

b/w rollers for ther

e

q

u

i

r

e

d

t

hi

c

k

n

e

s

s

.


18/96

FLATE

ENNG

MACHI

NE

This machine is used to straightening the job.

This is hydraulicallyoperated. In it, flattening load is applied

by hydraulic method;hydraulic oil of suitable grade is used. The

capacity of this machine is100 tons. The shape

of ram is cylindrical.

RADIAL

DRILLING

MACHINEIn this machine, tool can move radically. In it

cutting oil mixed withwater is used to cool the drill tool as used as the

material to be drilled.Different drill tools are used from

2mm to 100mm dia.

PLANO

MILLING

MACHINE

B

A

Y

(1,

2)These BAYS are known as assembly bays. Inthese bays, differentoperating

is to be

performe

d.Fitting

In this section, as the name

suggests, we fit differentcomponents as the

drawing requirements

.

Welding In this section, we weld the

different components ofdifferent drawing

by permanent

joints.Testing When our tank for the transformer is

completed, then wecheck the leakage tests on the tanks. There are

two types of leakagetests, which we have to perform on

the transformer tank.


19/96

1. AT

(Air

leakag

e test)

In this test, first we fill the tank by compressed

air and dip the tank inthe soap

solution for

bubble test.

2.

VT

(Defl

ectio

n

test)

Sh

o t

Bl

ast

ing

Pla

nt-

When we check the leakage by satisfying

result then we use SHOTBLASTING for removing the carbon layer from

the surface of the tank.In the SHOT BLASTING, we use the small rings

with the high pressureof 7kg.

Paintin

g

After shot blasting, we paint the tank

for corrosion resistant.

BAY

-3

It is split in two parts, half is consist of machine

shop and the other halfis consist of winding of

dry type transformer.

There is different type machines used in

section. These are listedbelow.

1. To

ol

Cu

tte

r

gri

nd

er

Used for cutting tool

also grinding them.

2. Hydrauli

c surface

grinder

It is consist of

magnetic

platform.Cooling

oils is used

as coolant.


20/96

3. Dr

ill

sh

ar

p

ma

chi

ne

It is used for

sharp the drill

bits bymeans

of

grindi

ng

wheel

.

4. Vertical

grinder

machine

It is used

for grinding

purpose

.

5. Hydr

aulic

power

press

Used for

straightening the

materialcapacity of this

machine is 25

tones.6. Resistancebrazing

machine

Used foroverlap

connectio

ns.7. B

e

n

d

s

a

w

m

a

c

h

i

ne

It is used for

cutting circular

object. Inthis machine blade width is inch

and thickness is inch.

8. E

l

e

c

t

r

i

c

f

u

r

n

a

c

e

Used

for

heating

the object.9. Hydraulic

punching

machine

Used for

making

small piecesof material for desire purpose.

Range of this machine is1

2

m

mt

o

2

5

0

m

m

.

10. Hydraulicshearing

machine

Used forcutting the

materialin range

between 12mm

to 25mm.11. L

a

t

h

e

m

a

c

h

i

n

e

There are mainly

three type of lathes

arethere these

are listed

as below.Turret lathe Used for heavy duty.

Range of this machine is2

5

0

m

m

t

o

3

0

0

m

m

.

Capstone lathe Used for light work,

range of this machine is2

0

mm

t

o

1

5

0

m

m

.

Center lathe It is used for light work and

range of this machineis

2

0

m

m

to

2

0

0

m

m

.


21/96

CO

PP

ER

SE

CT

IO

N

This part is only concern with copper cutting,

bending, tinning etc.Machine used

are as listed

below.a) S

h

e

ar

ing

m

ac

hi

n

e

: Range 4mm to 6mm and

length of the blade is830mm.

b) Hydraulic

power

press

: Used for straightening

the product.c) Tube

slitti

ng

mac

hine

: This machine is

developed here

and isused for cutting the tube along its

length and across itsdiameter. Its

blade thickness is

3 mm.d) F

l

y

p

r

e

s

sm

a

c

h

i

n

e

: It is fully mechanical and

is used to press thejob. It is operated mechanically by a

wheel, which is top on themachine.

e) Lin

cing

belt

mac

hine

: It

creates

a

smooth

surface.

BAY

4

Here winding work of the power

transformer is carried out.The coil of

transformer is of

four types.a) L

o

w

v

ol

ta

g

e

c

oi

l

b) H

i

g

h

v

o

lt

a

g

e

c

o

il

c) Tap coil

d) Tertiar

y coil


22/96

All the winding performed by the paper

insulation copper conductoror by continuously transposed conductor it also

made of copper. Theycan

arrange by

different

ways.

a) Reve

rse

secti

on

wind

ing

b) He

lic

al

wi

nding

c) I

n

t

er

l

i

n

k

e

d

w

i

n

d

i

ng

d) H

al

fs

e

ct

i

o

n

w

i

n

d

i

n

g

F igure showing Cast Resin Dry Type transformer find

utilization in main power ofindust

rial

plants

Arrangement and type of coil depends upon jobrequirements. Alsothe width and thickness of the conductors

are designed and aredecided by design department. Conductors used

for winding is in theform of very long spiral wound on a spool,

conductor is covered bycellulose

paper for

insulation

.


23/96


24/96

S

li

tt

i

n

g

m

a

c

h

i

n

e

:

used

to cut CRGO sheets

in different width. Ithas a circular cutter whose position can

be changed as per the

uire

ment

.

CNC

cropping line

pneumatic:

It contains only

one blade which

canrotate 90 about the sheet. It is

operated pneumatically.CNC

cropping line

hydraulic:

It is also used to

cut the CRGO sheet

itcontains two blades, one is fixed and otherrotates 90 above the

sheet. It is operated hydraulically. M4 quality

sheet 0.23-0.33 mm

h

i

c

k

n

e

s

s

i

s

u

s

e

d

.

Y-6

This shop is divided into two parts one is traction

transformer windingand other one consist of assembly of

traction transformer.These transformers are used in locomotive used in

the AC locomotivecalled freight locomotive transformer. These are

mainly of two types:Single phase (5400 KVA) and Three

phase (6500 KVA).For local train EMV (Electrical multiple unit

transformers) is to beused. These are also two type: Single phase

(1000 KVA) and Threep

h

a

s

e

(

1

50

0

K

V

A

).

The major difference is that it has various

output terminals. Thevarious outputs are required to supply the

machine of different ratingmounted on the loco. A tape changer is also

provided and is used toobtain supply of

different rating

power.


25/96

F igure showing Transformer to be installed in

Shatabdi Express Train.

The traction machine (DC Motor). Which

provide torque to the locoetc by changing taps from the electrical panel

on the driver desk thespeed of the

locomotive can be

changed.

BAY

7

In this bay various types of insulation are

prepared which is to beu

s

e

d

in

tr

a

n

sf

o

r

m

ers.

M

A

T

E

RI

A

L

US

E

D:


26/96


27/96

It is involved in manufacturing of instrument

transformer of 132KV and220 KV. Voltage Transformer, Current

Transformer and ESPtransfo

rmer.

INSTRUMENT

TRANSFORME

R:

The

se

areof

two

typ

es

a) Currenttransfo

rmer

(C.T.)

b) Voltage

transfor

mer

(V.T.)CURRENT

TRANSFO

RMERIt is step down transformer. High current is not

directly measured butby the current transformer is step down to lower

measurable values,whi

ch

is

gen

eral

lylow

.

Body

The main body is a bushing, it also act

as insulator in whichw

in

d

i

n

g

i

s

p

l

a

c

e

d

.

The CT has a

bottom and top

chamber. The top chamber is the cylindrical

tank of mild steel. It hasterminals for connection of HV coils. It

has a glass window toi

n

d

i

c

a

t

e

t

h

eo

il

l

e

v

e

l.

Below the top chamber there is

bushing made of porcelain.It has several folds and rain sheds

to provide a specificelectrical field distribution and long

leakage path. Somebushings are of cylindrical while

modern one is conical asamount of oil porcelain used is

reduced without anyu

n

d

es

i

r

a

b

l

e

e

f

f

e

c

t.

Bottom chamber house the

secondary winding. There isalso connection box to which the

connection low voltage(LV)

is

mad

e.

Windin

gs


28/96

The primary winding consists of hollow

copper/aluminum pipe bentfrom of U aluminum, used for low rating. For

higher rating a set ofwire is passed through the pipe. For still higher

rating, copper pipe isused and for highest rating copper pipe with

copper wire passingthrough it is used. This arrangement depends on

the current carryingcapacity. The bent portion of

primary as in the bottom chamberwhere as the free end is the top chamber. The

straight portion liesi

ns

i

d

e

t

h

e

b

u

s

h

i

n

g

.

The primary is wound with crepe paper

insulation goes in increasingas we go downwards in the bottom

chamber. The free ends areprovides with ferrules, which are small

hollow cylinder throughwhich wires can pass connection to the

primary are made throughthese ferrules. The secondary is divided in a

number of coils fordifferent set of tapings. Connections are

different taping are made inconnection box. Each coil has an annular

core of CRGO (siliconsteel).

VOLTAGE

TRANSFOR

MERThis is also step-down transformer the out of

construction is the same

as that of C.T. It has also a top chamber,bushing and a bottomchamber. The difference

is only in windings.


29/96

Windin

gsThe primary winding is of thick wire having a

few turns. The windingis heavily insulated with paper insulation. It

has a hollow cylinderpassing centrally through it, which houses the

secondary winding.The clean and painted with either enamel

or epoxy paint. Thecostumer gives the choice of paint. Epoxy paint

is generally used inchemical plant and seashore installation.

Terminals are then mark andrating and

diagram plate

is fixed.The job is sent to shipping department

which takes care of itsdispatch by packing

in the wooden boxes.

D

I

F

F

E

R

E

N

CE

:

- In current transformer,

primary has less turns thensecon

dary

and

vice

versa. ESP

TRANS

FORM

ER: -

The Electro static

precipitator

rectifiertransformer is used for environmental

application. It is used tofilter the suspended charged in the waste

uses of an industry.They are of particular use in thermal

power station and cementindustry.

The ESP is a single

phase transformer. It hasprimary and secondary windings. The

core is laminated and ismade up of CRGO sheet. It is a step up

transformer. An ACreactor is connected in series with

primary coil. The output ofthe transformer must be DC which is

obtained by rectifying ACusing a bridge rectifier (bridge rectifier

is a combination ofseveral hundred diodes). A radio frequency

chock (RF chock) isconnected in series with the DC output

for the protection ofsecondary circuit and filter circuit.

The output chosen thenegative because the particles of carbon arepositively charged.The dc output from the secondary is

given to a set of platearrange one after the others. Impurity

particles being positivelycharged stick to these plates, which

can be jerked off byhammer. For this a network of plant has to

be set up all across


30/96

the plants .This is very costly process in

comparison with thetransformer cost. A relevant is also

provided to prevent thetransformer from bursting it higher pressure

develops, inside it.It is the weakest point in the

transformer body. An oiltemperature indicator and the secondary

supply spark detectorare also provided. One side of the

transformer output is takenand the other side has a marshalling box

which is the controlbox

ofthe

tra

nsf

or

me

r.

BAY

9

Three types of transformer are

fabricated in this bay:

1. P

o

w

er

t

r

a

n

s

f

o

r

m

e

r

.

2. Dr

y

ty

pe

tra

ns

fo

r

m

er.

3. Rectifier type

transfo

rmer.1) POWER

TRANSF

ORMERPower transformer find their wide use in

electrical power system.Actually these are the transformer,

which have made A.C.transmission very easy. These are step up or

down transformer. Theprimary and secondary voltage of power

transformer comprisesmaterial for magnetic circuit terminals, tanning

switches, tank oil aswell

as

cooling

devi

ces.


31/96


32/96

transformer along with rectifier unit

efficiency are that it can beconnected to the supply lines. This being static

unit efficiency is high.It may appear to be power transformer,

but it differs in manyrespects, power transformer is used to step up

or down the voltagewhere rectifier, secondary of which

corresponds to the output DCvoltage.

The quality that makes a rectifier

transformer unique is:The LV of a rectifier transformer carry very high

current busher has tobe used for the connection

winding and terminals.Other associated equipment of rectifier

transformer is also housed inthe same tank. A rectifier transformer is

basically a constant currenttransformer and consequently KVA rating

changes with outputvoltages.

The rating of a transformer is in watts

greater than the rated DCpower output is required to provide for the

harmonic current ofdis

tor

ted

wa

ves

.

TEST

ING

TRANSFO

RMER

TESTINGIn this shop testing on the transformer is

carried out in one sectionand for loco in other section. In transformer

testing section there arefor MG. sets. The electrical specification of the

entire test is alreadygiven. These tests are done on demand of

customer on transformermanufactured, in this unit there

are basically of test.1. T

YP

E

TE

ST

This test is done in a

single unit of that type.

2. R

O

U

TI

N

E

T

E

S

T

Bach and every

unit has to be

testedindividu

al.


33/96

(a) For power

transformer

routine testRatio

test:

Special

equipment

transformer fromrouti

ne

mete

r.

R

es

is

ta

nc

e

te

st

:

Special

equipments

Kelvin andW

h

e

at

s

t

o

n

e

b

r

i

d

g

e

.

Insulati

onresistan

ce test:

Special

equipment

megger.

Separate source

voltage withstand test:

Special

equipments HV transformers

with associated controland measuring desk, standard

capacitance potentialdivider.

Iron loss

measureme

nt test :

S

p

e

c

i

a

l

e

q

u

i

p

m

e

n

t

:

El

ect

ro

dy

na

m

om

ete

r

RM

S

volt

met

er

A

v

e

r

a

g

e

v

o

l

t

m

e

t

e

r

Precision

classmeasuring

VT

Variable frequency

sine wave generator

TEST OF CURRENT

TRANSFORMER

1. P

O

L

A

RI

T

Y

T

E

ST

:

INST

RUM

ENT

USE

D:

Polarity meter

analog

multimeterOne of the winding is supplied with 1.5V

D.C supply and other isconnected to ammeter. If the direction of the

deflection is correctimplies the connections are correct else it is

wrongly connected.

2. AC

CU

RA

CY

TE

ST

:

It is the test for

checking the turn ratio

steps:


34/96

A standard transformer primary

is connected acrossthe

pri

ma

ry

of

the

job

.

As the no. of turns of the

secondary transformer isknown the no. of turns of

secondary of job iscalculat

ed.The ratio is taken and the

max permissible error

should be not more than thatspecified by the design.Even the phase angle is

checked for this maxp

e

r

m

is

si

b

le

li

m

it

.

3. INTER TURN

INSULATION

TEST :Checks for the

insulation of the

transformer Current is given to primary

and secondary is opencircuited.

Either of the rated primary

current or the 4.5KV peaksecondary voltageswhichever appears first isallowed to

withstand

for 1 min.Then if the insulation can

withstand then it is said tobe okay.

4. WINDIN

G

RESISTA

NCE :Error in winding resistance appears if the

conductors of differentlength are used if the conductors are joined in

between to check thiswinding resistance is checked and if it

appears then the internalpoints of

connections

is changed. TRANSFORMER

COMMERCIAL (TRC)


35/96

The objective of this department is to interact

with the customers. Itbrings out tenders arid notices and also

responds to them. It isdepartment that places the contracts of building

the transformer andafter delivery further interacts with the

customer regarding faults,failure and maintenance is done by this

department. All such snagsare reported to them and they forward

the information to the

concern

ing

dep

art

men

t.

The works of the

commercial department

are: T

e

n

d

e

r

s

a

n

d

n

o

t

i

c

e

s

Interaction

with design

departmentPlac

e of

workApproxima

te cost of

the workEar

nestmon

eyPlace and time where contract

document can be seen.

Amount if any to be paid

for such document

TENDERS

AND

NOTICES:The department response to the tenders

calls of companies ororganization which requires transformer.

Contracts are baggedth

rou

g

h

n

e

g

ot

ia

ti

o

n

s.

The department also invites tenders and

notices. Before invitingtenders it must be sure that BHEL is ready to

undertake the contractand before full knowledge of scope

of work is essential.


36/96


37/96

in 4 or 6 equal steps. The type of tap

changer depends on theapplication of the transformer. Where a

continuous power supply isnot required an Off Circuit Tap Changer (OCTC)

may be used. Wherea continuous power supply is must e.g. at

substation in cities etc. OnLoad Tap

Changer (OLTC)

is used.

T

E

C

H

N

O

L

O

G

Y

This department analyses the changes taking

place in the world andsuggest changes accordingly. This is very

important because theproduct must not get obsolete in the market

otherwise they will berej

ec

ted

by

cu

st

o

m

er.

Function:

Technology functioncan be classified as:

Pro

cess

ing

seq

uen

ce

: The

sequenc

e of

process

of

manufacturing is decided for

timely and economicco

m

ple

tio

n

of

the

jo

b.

Operati

on time

estimat

e

: I

t

i

n

c

l

u

d

e

si

n

c

e

n

t

i

v

e

sc

he

m

e

m

an

age

m

en

t.

Allowe

d

operat

ion

time

: I

t

i

nc

l

u

d

e

s

i

n

c

e

n

t

i

ve

amount.

Facili

tie sidenti

ficatio

n

: It

includes

looking

for new

equipment, plant or tools to

increase productivity.Special

process ce

rtification:

S

pe

ci

al

pr

oc

es

se

s

ar

e

the once required expertise for

example identifyingerrors, cracks, air

bubble in

winding.


38/96

Special

tool re

quiremen

t:

Speci

al

tools

are

allott

ed

if possible. When required else

the design has to bereconsi

der.Productivity

projects

compilation:

It

inclu

des

the

initial analysis of the problem

and their appropriatesolution to

enhance

productivity.

The

principle of

working is

that

IF YOU DONT

MAKE CHANGES INYOUR COMPANY, THE COUSTMER WILL

CHANGE YOU.

BUS

DU

CT Bus duct is used as connectionbetween generators andtransformer. Bus duct are used in power

connection over 150 M V.The question now arise that why are bus duct

preferred over normalconductors. In high power application,

insulations are the majorproblems and frequent insulation

breakdown occurs. If this doeshappens then possibility of shorting of

conductors and hence seriousdamage may occur to both

transformer and generators.

Bus duct are hollow pipes made of aluminum

the cross section ofthese ducts depends on requirements of the

customer and is done bythe

des

igndep

art

me

nt.

The cross section may have differentshapes, circular, squarehexagon, octagon. The casing is also made

of aluminum sheets.Althou

gh

alumin

um is

not

a good conductor as

copper still is preferred


39/96

over it because it is lighter than copper.

Moreover, it is cheaper thancopper.

Bus

duct

are of

two

types:

a. Segregate

d Bus

Duct(SBD

)

b. Isolat

ed

BusDuct(

IBD)

In segregated bus duct one casing isdivided into three separatechambers for the three phases. In isolated bus

duct is provided intoseparate casing. The conductors i.e. duct is

separated from the casingby proclaim or epoxies

(chemical) insulators.

Bus duct assembly

contains three cubicles

P.

T.

an

d

S.

P.cu

bi

cl

es

N.G.

cubic

les L

.

A.

V

.

T

.

c

u

b

i

c

l

e

s

These cubicles have the circuit and the

controls of the bus ductassembly. The connection may be star or

delta. The lines enterfrom the top of the chamber. The top chamber

has the neutral sideand the line side. The aluminum conductor in

bus duct is not solidbecause of ac has skin effect i.e. it flows

only on outer surface ofconductor then why to waste money on the

remaining conductor,so we simply remove that part so it

is hollow conductor.


40/96

L

O

C

O

M

O

TI

VE

A locomotive is a rail vehicle that provides

the motive power for atrain.

Loco

means

from a

place

Motive

means

causing

motion.

A locomotive has no payload capacity of its own.

It is used to move atrain.

The trains which have self propelled pay load

carrying vehicles arecalled Multiple

Units (MU) or rail

cares.

CLASSIFICATION OF

LOCOMOTIVE

By

thei

r

use:

Pass

enger

Loc

omo

tive

F

r

i

g

h

t

L

o

c

o

m

o

t

i

v

e

Shunting

(switcher)

Locomotive

By their

source of

energyS

t

e

a

m

Lo

c

o

m

o

t

i

v

e

D

i

e

s

e

l

L

o

c

o

m

o

t

i

v

e

diese

l

electr

ic

die

selhy

dra

uli

c

E

l

e

c

tr

i

c

L

o

c

o

m

o

ti

ve

M

a

g

n

e

t

i

c

L

e

v

i

ta

t

i

o

n

H

y

b

r

i

d

L

o

c

o

mo

t

i

v

e


41/96

Ste

am

Lo

co

mo

tiv

e

Less efficiency in comparison to electric

and diesel locomotiveRequires more

manpower to

operate.Use in countries where coal is much more

abundant source thandiesel

fuel.Use at mountains and high attitudes rail

lines as they are lessaffected by

reduced air

pressure.

D

ie

s

el

L

o

c

o

m

o

ti

v

e

Powered by internal

combustion engine.Power Transmission-output of prime

mover to driving wheels. By coupling Alternator/Generator to

prime mover. (DieselElectric)

By coupling torque converter to

prime mover. (DieselHydraul

ic)Requires less maintenance as compared to

steam locomotives.

Ele

ctri

c

Loc

om

otiv

e

Electric power supplied extremely through

an overhead pickup(centenary) or

through a

third rail.High performance and

low operation cost.Capital cost of

electrifying track is

high.Spe

ed

up

to

575

km/

hr.

Can also

operate on

battery power.


42/96

Battery locomotives which are used in

mines and undergroundlocation.

Mag

netic

Loco

moti

ve

New

techn

olog

y in

train.

It floats the train above the

rail without wheels.Re

du

ce

fric

tio

n.

C

o

st

is

v

e

r

y

h

i

g

h.

Hy

bri

d

Lo

co

mo

tiv

e

Used on board rechargeable

energy storage system.

Locomotives

manufactured at

BHELEl

ec

tri

cL

oc

o

m

ot

iv

es

WAG-5

WC

A

M

-

2

A

C

/

D

C

W

C

A

M

-

3

A

C

/

D

C

WCAG-

1Main customer:

INDIAN

RAILWAYS

Diesel

Shunting

LocomotiveDie

sel

Ecle

ctic

350

HP

DES

L

450

HPDES

L

700HP

SPP/

TPP

DES

L

1150

DESL1350

DESL1400

DESL


43/96

2600

DESLMain customer: Power plants, Steel Plants,

Cement Plants, CoalMine, Port trust

and Fertilizer

plants.

F igure showing a 25 KV AC/1500V DC AC/DC

locomotive type WCAM-3

DieselHydraulic

Locomotive800

HP

DH

SL

Custome

r:

IFFCO,

KandalaBat

ter

y

Lo

co

mo

tiv

e

450 HP

Customer:

DMRC,

New DelhiNe

w

Pr

od

uct

s

OH

E

reco

rdin

g

test

car.

2

0

0

M

T

w

e

ll

w

a

g

o

n.

Rail cum

Road

Vehicle

(RRV).

Util

ity

Veh

icle.


44/96

Diesel Electric

Tower Car

(DETC).Battery Powered

Road Vehicle

(BPRV).Synchrol

ift Hoist

Assembl

y.

Dynamic

Track

Stabilizer

(DTS).

Ballast

Cleaning

Machine

(BCM).

F igure demonstrating 700 hptwin power-pack DESL.

Main Parts of

Diesel

LocomotivesUnder Frame: The one on which a

locomotive is built.Super Structure: The body of locomotive is

called superstructureis made of

sheet of

mild steel.Bogie: The wheel arrangement of loco is

called bogie. A bogiee

s

se

n

ti

a

l

c

o

n

t

a

i

n

s.

Bogie

frame Wh

eel

and

axl

e

Tra

ctio

n

mot

or

Ge

ar

an

d

pin

ion


45/96

Brake

shoe Pull rod

Sand box

Springs

Bra

ke

cyli

nder

Main

Equipme

nt of

DESLTraction

Alternator/

Generator.Tra

cti

on

Mo

tor.

Blower.

Compr

essor

or

Expres

ser.

Swit

chge

ar

Equi

pme

nts

Drive

Desk.Fuel

Tank.Batteries

Radiator

Br

ak

e

Sy

ste

m

Simple

Air

Brake

Syste

m.

Air Brake System

with MU

operationAir Brake System with MU Operation and

air break on trailingstock.

Dual Break System-Air and

Vacuum.

Ene

rgy

Tra

nsm

issio

n


46/96

In DESL

In DHSL

Mechanical Energy

Mechanical Energy

Electrical Energy

Hydraulic Energy

Mechanical Energy

Mechanical Energy

Tracti

onTransf

ormer

:

It is fixed on under frame

and gets supply froman overhead line by equipment called

pantograph. The type ofpantograph depends on supply. This transformer

steps down voltageand is fitted

with a tap

changer.

Different taps

are taken from

it foroperating different equipment. One tap is

taken rectified into DCusing MSR and is

fed to the DC

motor.

STO

RE

There are

three sections

in store : Contro

l

Receiv

ing

Sectio

n

C

us

to

dy

Se

cti

on

Scr

ap

Dis

pos

al

Sec

tion

Functi

ons:

A list of material coming in store is

prepared and QualityControl people are called for inspection. If

material is found as parstandard SRV (Store Receipt Voucher) is issued

for each material. Atotal of 08 SVRs are prepared. Some

materials such as Silicon oil,Transformer oil, insulating material etc are

directly stored in the Bays.


47/96

CENTRAL

QUALITY

SERVICE

First we get acquainted with a few termsconcerning this department.

Quality: It is the extent to which product

and service satisfy thecu

sto

me

r

ne

ed

s.

Q

u

a

l

i

t

y

a

s

s

u

r

a

n

c

e

: All those plants and systematic

action necessary toprovide adequate confidence that the

product or the service willsatisfy the given requirement is

called quality assurance.

Q

u

a

li

t

y

c

o

n

t

r

o

l

:

Activity such as measuring

testing, gauging one ormore characteristics of product or service and

comparing these withspecified requirement to determineconformity are termed quality

section.

WORK ENGINEERING AND

SERVICES (WE&S)

As the name suggest this section

deals with services andmaint

enanc

e. It has

follo

wing

Secti

ons:

P

l

a

n

t

E

q

u

i

p

m

en

t

:

This has electronics and

electrical/mechanicalmaint

enanc

e.


48/96

Service

s:

This section deals with

air, steam and powerequip

ments.

Telep

ho ne

Exch

ange:Township

Electrical

Maintenance:W

E

&

S

P

l

a

n

n

i

ng

This section deals with

stores and new machinesprocurement and others general things. There

are three maintenancecenters at Bay 2, Substation and LOCO.

This section is alsoresponsible for power

distribution is of two types:

HT POWERDISTRIBUT

ION

: This is at 11KV, OCB are

used forprotection. There are four substations

for this distribution.

LT

DIS

TR

IB

UT

IO

N:

This is for the auxiliary in

each shop and othersection of BHEL. It uses OCB/OVB/ BHEL

(Bhopal), 800 KVA, 11KVA 45 V transformer and ACB (English

Electro).TransformerSupplied with enclosure of IP 23 class of

protection. Bushing ofcables boxes are provided for HT

and LT connections.

These transformers are used inunderground substation, highbuilding and hotels, under the roof

installation, power plant etc.


49/96

PROJECT

REPORTON CNC

MACHINES


50/96

INTRODUCTION AND GENERAL WORKING OF

CNC MACHINE

CNC machine tools have been widely

accepted as time provenmanufacturing technique all over the

globe. In India too, CNCmachine have picked up momentum and Indian

Industries are goingfor more and

more CNCmachine.Numerical control turns machine tools into a

flexible production unitwith a multitude of possible application.

Although at first they weremainly used for manufacture of geometrically

complicated parts,numerical control were later used for added

enhanced efficiency inthe medium batch production of turned and

milled parts. The nextstep is the introduction of numerical

controls in all sections ofproductions. The aim in all the cases is to

combine high productivitywith flexible

possibilities of NC

technology.Other machine processes are being added to

turning and millingwhich may be already described as

classical NC applications.Conventional methods are being replaced by

NC for sheet metal-working processes of punching, nibbling and

cutting. Productivityincreases multifold using numerical

control with grinder, gearhobber

s and

spark

erosion

.ELECTRONIC REVOLUTION AND

COMPUTER GROWTH

Modern day computerized numerical control

system (CNC) is theresult of advancement and sky rocketing

microelectronics with everyday breaks its own record and grow by leaps and

bounds. Initially NCmachines had as many as 280 printed circuitboard (PCB) and quiteextensive wiring which consequently made

maintenance very difficultand reliability was poor. First generation NC

system had transistorelements.


51/96

With advent of integrated circuits only 40

PCBs were used withreduced wiring for the system. Further

integration called MediumScale Integration (MSI) replaced nearly 10 ICs

and system involvedonly 5 to 10 PCBs. With arrival of

what is known as age ofMicroprocessors and Very Large Scale

Integration (VLSI) technique,modern day CNC machines use only 2 to 4

PCBs. The trend withmicroprocessors helps in lowering cost of

jobs and increment inreliability

toappreciabl

e label.

Flexibility as inherent feature of minicomputer

and microcomputergave new technology

Software Oriented System.Unlike rigid hardwire system which had been

used hitherto, this newsystem

comes

to

market

as

COMPUTER

NUMERICAL

CONTROL(CNC) system.

With this latest technology, hardware cost of

CNC system loweredconsiderably whereas flexibility increased

multifold due to softwarecapabil

ities.

WORKING PRINCIPLE OFNC MACHINESElectronic industries association defines

numerical control as Asystem in which action is controlled by direct

insertion of numericaldata. The system must automatically interpret at

least some potion ofdata.

In simple word numerical control means control

by numbers. In NCmachine tools the main function is to control

the displacement andpositioning of slides, spindle, speed, feed rate,

selection of tool andmany other auxiliary functions. NC directs the

machine tool to achieveall these function in a very controlled and

systematic manner .Themajor elements that comprises NC

machine tools are :-Con

trol

syst

em

CN

C

T

h

e

m

a

c

h

i

n

e

t

o

ol

Se

rv

o

dr

iv

e

un

its


52/96

F

e

e

d

b

a

c

k

d

e

v

i

c

e

s

O

pe

rat

or

co

nt

ro

l

E

le

ct

ri

c

al

ca

bi

n

et

Schem atic diagram

representation of NC m achine

tool

In CNC system, tape instructions are read

by tape reader. Theseinstructions undergo electronic processing and

system gives outputin the form of electrical signal to servo drive of

the machine tool todetermine the length of movement and feed rates.

System also directscommands to various relays, solenoids etc to

initiate operation of themachine tools such as spindle motor starting

and stopping , coolantsupply , auto tool change and other

miscellaneous functions.Once the machine tool has commenced its

operation and operativeelement and moving , it become necessary toensure that requiredlengths of movements have taken place or a

particular function hasbeen accomplished. This is done by

feedback devices. Positionfeedback devices like linear scales, encoder,

resolvers, inductosynfeedback status of actual position of slides

to control system. A


53/96

velocity feedback transducer known as

Tachogenertor is used forvelocity control as warranted during

contouring operation . Feedback of auto tool change function etc are

taken from proximitysensors or limit switches. Thus all

operations of machine aremonitored continuously with appropriate

feedback devices. In case offailure or adverse feedback received by system ,

machine stops andsystem displays Fault message

in clear English text.

TY

P

E

S

O

F

N

C

Based on feedback, NC system can be broadly

classified in two typesas Open loop and closed loop. The open

loop system has nofeedback, whereas closed loop system utilizes

feedback transducerswhich continuously monitor the position

of slides. This enablemachine to achieve a very high degree

of accuracy in slidedispla

ceme

nt

F igure above

showing open

loop system .

From metal removal point of view, the

classification can be made aspoint to point, straight cut and contouring

system. In point to pointsystem, the machine performs machining

operations at specificpositions and does not affect work piece while

moving from one pointto another. An example of this type isNC drilling machine.


54/96

F igure

showing

closed loop

system.

Straight cut or straight line system provides

movement at controlledfeed rate in one axis direction at one time. The

examples of this areface milling,

pocket

milling etc.

F igure demonstrating NC systems some

of different paths and cut.

The continuous path control system calls for co-ordinate movement ofthe tool and work piece along different axes.

This enables machiningof complex profiles, contours

and curved surfaces.


55/96

MACHINE TOOL

REQUIREMENTIn a NC machine certain design features are

desirable on machinetool. Simultaneous movement of 2 or more

axes and high removalcapability of NC machines demand high

dynamic stiffness in drivesand also stiff structural elements. The structure of

NC machines shouldbe very rigid to withstand heavy cuts and it

must be maintained forlong time to

obtain high

accuracies.High positioning accuracy needed in NC machinemake it essential tohave backlash free screw and nut and slides with

a very low friction ofco-efficient. This is achieved by ground re

circulating ball screw andnut, tachoway bearings, hardened and ground

guideways and frictionreducing linears such as

Turcite and PTFE.Electronic spindle drives on NC machines

facilitate step less speedover a

wide

range of

RPMs.

All axes are driven by powerful DC Servo drives

controlled by PWMor SCR controllers through preloaded

ball screw and nuts.Automatic tool changer, centralized lubrication

system, index table orfourth axis is commonfeatures on NC machines.A

C

C

U

R

A

C

I

E

S

CNC machines ensure better and

consistent accuracies on jobcompared to conventional machines.

Positioning accuracies to beextent of +10 or -10 microns and repeatability of

+5 or-5 microns canbe achieved in NC machines depending

on the elements used.

Parts Suitable For

CNC Machines:-To utilize the CNC machine effectively

and economically thesuitable pats selection is very important, thefollowing guideliness

h

o

u

l

d

b

e

o

b

s

e

rv

e

d

:

High number of

operation per

component.Comp

lexity

of

operat

ion.


56/96

Size

of

batch

es

medi

um.

Repetitions

of batches

are often.Labor cost of

component is

high.Requires

substanti

al

tooling.

Requir

es

100%

inspection.

Setup and

inspectiontime is high.Ration of cutting time to non-

cutting time is high.Varieties of components

produced are more.Skilled required

by operator is

high.

GUIDELINES FOR EFFECTIVE UTILIZATION OF

CNC MACHINESWhen a company or organization first decides to

buy CNC machine,Orientation at all material level is required to get

maximum return outof huge investment made. It is not

sufficient that managementunderstands the benefit of machine and decided

to buy one, instead adeep insight of CNC technology is must and will

quite obviously helpsin buying suitable one and keeping its idle time

minimum. FollowingAre few point for effective

utilization of CNC machine.It is vital that time taken for machine to

become productive isas short as possible. The key to good

CNC machine lies inprior planning, which should start

the day managementdecides to

buy CNC

machine.Programmers, maintenance people and

operators should beselected and trained

before CNC arrives.

Foundation and electric supplyrequirement should readybef

ore

mac

hine

arri

ves.


57/96

For small organizations where experts

and maintenance staffsare generally not available, proper

support from suppliers

h

o

u

l

d

be

e

n

s

u

r

e

d

.

It should be ensured that suppliers of NC

machines provide with allrelevant technical

documents for the

machine.While NC can be out product its manual

counterpart 3 to 4 times,you can just easily loose this multi

machine capacity duringbreakdown. To keep downtime minimum,sufficient quantities ofspare are recommended by suppliers of

machine should bemaintain. Also it is always make sure that

supplier of machinestocks critical

parts and

accessories.Sufficient thought should be given to

tooling, accessories and allother peripherals

that surround

CNC.CNC machines must be placed at

convenient places in the shopconsidering work flow and material

handling. We cant keep NCmachine waiting while we are searching for

tools or waiting foravailabili

ty of raw

materials.Future expandability should always be indecision making whilebuyi

ng a

CNC

mach

ine.

Clean and dust free environment should

be ensured in shop inorder to minimize breakdown efficient

working and consequentlylonger

life of

CNC

machine.GENERAL INTRODUCTION TO

MECHANICAL ANDHYD

RAU

LIC

ITE

MSMECHANIC

AL

ITEM

S1. Re-circulating linear roller

bearing (Tychoways)


58/96

Good performance, high precision and high

efficiency are quiteobvious requirements which CNC machines

are required to fulfill.Preconditions are basically good performance;

high precision andhigh efficiency are minimum wear rigidity and

low friction. Theseconditions are fulfilled by re circulating

linear roller bearings.The main characteristics of these bearing

are continuous rollercirculation which follows unlimited

linear movement andelimination of the stick-slip effect

which makes accuratepositioning of

machine,

possible.Tychoways consists of hardened, high

precision machined,supporting elements, head pieces which

are screwed on to thefront face, and a number of cylindrical

rollers. As with cylindricalroller bearings, the rollers are guided

between the shoulders ofthe supporting elements with a very close

tolerance. Thereforeskewing the roller and resulting the

additional friction as well asthe forces acting at the right angle to the

rolling direction can beavoided to a large extent. The retaining

element made from theplastic material and situated between the

rollers not only preventsthe roller from falling out and sliding against

each other but alsoresults in smooth return of rolling

element to the return zone.Elastic strippers which are built into

head pieces provide thebearing with effective protection

from foreign matters.Tychoways are suitable for grease and oil

lubrication and can beused in temperature range from 30

degree to 90 degree.

2. Torsion

ally stiff

couplin

g

These flexible coupling without backlash

are specially designedfor servo or variable speed drives. They

guarantee an accuratetransmission for angle of rotation even in

presence of alignment


59/96

errors e.g. between motor shafts and ball

screw of machine tools.The special design for metal body allows a

high torsional stiffnesswhich frequently exceeds the motor shaft

itself. The bearing loadis kept low due to low lateral spring load

stiffness. The conical hubsprovide a positive detachable connection

between coupling andshaft, without use of additional elements.

Since there are no partssubject to wear, couplings

are maintenance free.

3. Angular contact ball

bearings for spindleBall bearings for machine tools must

support radial loadscombined with thrust loads in either

direction. For this reasonpreloaded, angular contact ball bearing are

generally used. Thesebearings are available with high (25

degree) and (15 degree)contact angles. In selecting the proper

sizes and type bearing,consideration is given to size and

construction of spindle and thekind of mounting, since the latter relates

directly to the contactsspindle rigidity and

deflection characteristics.In general where the operating load is

principally radial, low contactangle type bearings are selected, but where the

loading is chiefly inthr

ust

an

d

hig

h

de

gre

e

of axial rigidity is

required, higher

contactangle type of bearings

are recommended.


60/96

Also three bearings are preloaded to

reduce axial and radialdeflection and may be mounted in three

different arrangementsi) Back

-to-

backii) Face-

to

faceiii) Tamdem

In back-to back (D3) mounting, the most

commonly used thestamped faces of the bearing outer ringproject beyond theinner ring and about each other. The

angular line of contact ofthese bearing diverges in direction of

rotation of axis, resultingin both axial and radial rigidity of the

shaft and providingmaximum rigidity to the deflection.

Upon clamping the innerring together by tightening the inner

ring locknut, a load isimposed through a ball and the outer

rings. This takes up theinternal clearance and places these

members in compression.The initial amount of offset or clearance

between the inner ringfaces, therefore, determines the

amount of preload.When bearings are mounted face-to face

(DF) that is with theunstamped faces of four rings together,

the angular lines ofcontact of bearing converge in direction

of rotational axis andthe inner rings project beyond the

narrow faces of the outerrings. When the outer ring is

clamped together, the initialclearance between the outer rings is

taken up, preloading thebearing.


61/96


62/96


63/96


64/96

DOUBLE SOLENOID SPRING CENTERED

DIRECTIONALCO

NT

RO

L

VA

LV

E

In this type of valve there are three positions of

valve spool. Controlspring acting on the both ends of the spool

keeps it to the centralposition when both solenoids are energized.

To hold on extremeposition one solenoid should be

continuously energized.

These valves are also kept in DG4 series byVickers. The schematicrepresentation by this valve is

shown in figure below:


65/96

And its

graphical

symbol

is:

The valve in the figure shown above is in

central position. In thisposition the central port is closed and port A

and B are open to tank.Since there are 3 positions and four

connections it is also called di

re

cti

on

al

va

lv

e.

In all solenoid electric energy supplied to the

coil create magneticfield by virtue phenomena of

electromagnetic induction, whichconsequently draws armature into the coil. The

armature motion inturns push rod or can be seen as transmitted

via push rod which intur

ns

mo

ves

thesp

ool

.

PRESSURE OPERATEDCHECK MODULEThese modules contain a check valve in both

cylinder portion checkvalve allows free flow of oil in one direction.

They are arranged forfree flow out of

the directional

valve.For return flow one check can be unseated

by a common strikerpiston, mounted co-axially between two checks.

This happens wheninternal pressure on one side is sufficient to

cause the striker piston toopen the check valve on the other

side. At neutral position,compression spring will seat the check and

machine actuator will behel

d

stati

ona

ry.

Within each poppet piston, is a small

decompression poppet whichopens before

the main check

valve.


66/96

NON PRESSURE COMPENSATED FLOW

CONTROL VALVE(WITH

CHECK

VALVE)Flow control valves are used to regulate thespeed of actuator bycontrolling the flow of oil from the pump.

There are three basicmethods of applying volume

control valve in a circuita) Meter-in

b) Meter-

outc) Bleed-off

In meter-in operation, the flow control valve

is placed between thepump and the actuator. In meter-out it is

located in the tank line. Inbleed-off arrangement the flow control valve is

kept in the pressureline and diverts excess flow to the tank, thus

permitting only requireflow

pass

through

actuator

.

Meter-out control finds advantage over

the others in the NCmachines. If the load turns to run away

it will it will regulateactuator speed because it restricts exhaust flow

from actuator. Otheradvantage is that being in a low pressureline losses are less.A check valve is incorporated for free flow

in reverse direction.

The figure above demo nstrate s the meter -out flow control


67/96

Graphical symbol along with the internal constr uction

of non-compe nsated flowcontrol

valve.

NON-COMPENSATED DUAL

CONSTRUCTION FLOWCO

NT

RO

L

VA

LV

E

It regulates flow rate between DG 4 (4 way

valve) and hydraulicactuator.

Graphical repr esentation of this

valve is shown in figur e.


68/96

Dual valve construction permits free flow to

both actuator port andadjustable independent flow regulation in

each return line fromactuator.

PRESSURE AND TEMP. COMPENSATED

FLOW CONTROLVALVE

Since the flow through an orifice is

essentially proportional to the p across it.

This meansthat any

square root

of thepressure

drop

appreciable change in the work load

would affect the speed.To overcome this problem one is made of

pressure compensationdevice. A hydrostatic is utilized to maintain a

constant pressure dropacross

an

adjustabl

e

throttle.

Since flow through a pressure compensated

flow control valve issubject to change with variation in oil

temperature, so a temperaturecompensating rod which lengthens when hot and

contracts when coldis incorporated in valve. The throttle is simpler

plunger that is movedin and out of the control port. The

compensating rod is installedbetween the throttle and its adjuster. Viscosity

of oil decreases with

temperature tending to flow freely, but thethrottle opening is alsoreduced with the help

of compensating rod.A reverse free-flow check valve is also

included in the valve. Aschematic representation and internal

construction is shown in thegiv

en

fig

ure

.

.


69/96

PRESSURE

RELIEF

VALVEThe pressure relief valve limits pressure in

the system to a presetmaximum by diverting some or all of the pumps

output to tank whenthe pressure setting is reached. It is a infinite

positioning valve i.e. thevalve can assume various position betweenfully closed and fullyopen, depending on flow rate and

pressure differential.It consists of a ball held seated in the valve

body by a heavy spring.When pressure of inlet is insufficient to

overcome the force of spring,the valve remaining closed. Then the preset

pressure is reached, theball is forced off its seat and allows throw out the

outlet to tank for aslong as pressure is maintained. An adjusting

screw is provided tovary the spring force. Thus the valve can

be set to open at anypressure within its specified range. The valve

is shown in the givenfigure


70/96

PRESSURE

REDUCING

VALVEPressure reducing valves are normally open

pressure controls usedto maintain reduced pressure in certain

application. They areactuated by pressure sensed in the branch circuitand tend to close asit reaches the valve setting, thus

preventing further build up.It is self operated type valve. The spring force on

one side is opposedby a pressure on the other side. Rising system

pressure acts againstthe spring to close the flow path. The leakage

oil is internally ventedto tank with all valves. If the valve closes

completely, leakage pastcould cause pressure to build up in the branch

circuit, so a continuousbleed to tank is permitted to keep it

slightly open, and preventdownstream pressure from rising above the

valve setting. A drainpassage is provided to return this

leakage flow to tank.


71/96

A direct acting pressur e reducing valve is

shown in the above figur e...

HYD

RAU

LIC

MOT

OR

Hydraulic motor converts hydraulic energy

(pressure * oil flow) intomechanical energy (torque * speed). Hydraulic

motors are of variousdesigns. One type is gear motor. This consists

of following maincomp

onents

:1. Gea

r

whe

el

set

2. Commuta

tor valve

with shaft3. Drive

4. Housing

The gear wheel set has an outer ring which is

built together with thehousing with (n+1) internal teeth and an

internal rotor with externalteeth. The teeth of the ring and rotor are

meshing together. The rotorhas one tooth less then the ring, and this result

in the so-called gear


72/96

wheel spaces between the ring and rotor. One

half of these spacesare connected to the delivery side of motor. A

simpler rotary flowdivider valve guides the liquid in such a way

that the delivery andreturn spaces rotate synchronously with the rotor.

The drive forms themechanical connection between the

commutator valve and the rotor.The rotor movement is the combination of

rotation and translation.The drives have splines at either end

and allow only rotarymovem

ent.Pressure required in hydraulic motor depends on

the torque load anddisplacement. A large displacement motor

will develop a giventorque with less pressure

than a smaller unit.

CY

CL

IN

DE

R

Cylinder is a linear actuator i.e. output of a

cylinder is straight linemotion. It is classified as single or double

acting. Single actingcylinder has only one fluid chamber and exerts

pressure in only onedirection. It is mounted vertically and retracts by

the force of gravity.Head counterbalancedcylinders are of this type.


73/96

A cylinder consists of a barrel, a piston and rod,

end cops and seals.Barrel is seamless steel tubing and piston is

made of C.I. or steel.These cylinders also have provision for

adjustable cushioning at bothends for smooth beginning

and end of the stroke.PRE

SSU

RE

SWI

TCH

Pressure switches are used to make or break

electrical circuits atselected pressures to actuate solenoid

operated valves or otherdevices. They can be used to provide ON/OFFsignal which can befed into an

electronic

control system

.

Movement of piston under pressure against a

spring operates a microswitch. The spring is of corrugated diaphragm

type. A restrictor isusually fitted in the pressure inlet to reduce the

effect on the switch ofany hydraulic shock

loading in the system.The pressure setting of the switch can be

adjusted by turning anadjusting nut. A switching differential is

provided in pressure switch.It means that switch will operate at certain

pressure and above whenpressure is being raised, but when pressure falls

it will not operate atcertain pressure lower than operating pressure.

Difference is calledswitching differential and is essential to avoid

tripping of machinefrequent

ly.

GENERAL INTRODUCTION TO

ELECTRICAL ANDELECT

RONIC

S

ITEMS

1.

Prox

imit

y

Swit

ches

Proximity switches are solid state switching

device which required nophysical contact to actuate them. These

are use for control andpositioning signals because of long life, high

switching speed, notouch, zero operation force, wear andmaintenance free operation,bounce free signal and reliable switching under

extreme conditions.It comprises of

three principle

partsi) Oscillato

r


74/96

ii) T

r

i

g

g

e

r

s

t

a

g

e

a

n

d

iii) A

mp

lifi

er

sta

ge

To obtain a switching signal at given

voltage and temperature,sensing distance (Sn) is the main factor.

Sensing distance is themaximum distance between the target and the

sensing face. Sensingface is the surface from which the

electromagnetic field radiates.

Sn depends upon material,thickness and area of target.Target diameter =

Oscillator Unit

Diameter2.

L

i

m

it

S

w

it

c

h

Limit switches are used to make or break

control circuit whenmechanically actuated by a moving member.

Moving member mightbe a dog mounted on the moving component, as

in the case of travelor over travel limit switches, or may be of plunger

actuated type as incase of filter clogged limit switch. The limit

switch type may be ofnormally open type (NO) which will close when

switch is actuated ornormally close type (NC)

which will actuated.

3.C

ir

c

u

it

B

r

e

a

k

e

r

A device designed to open and close by non

automatic means and toopen the circuit automatically on the

predetermined overload ofcurrent, when properly, applied within its rating.

Two types are there:1) Thermal

2) Hydrauli

cThermal circuit breakers responds only to

temperature change in thebimetallic element. Heat is generated in the

element because of i

r2

losses. The element bends or deformed to

open the contacts andunlatch the mechanism. Mainly used MCB

(Miniature Circuit Breaker)offer dual protection i.e., protection

against overload and shortcircuit.

MCBs are preferred over fuses as it

disconnects supplyinstantaneously, and requires

seldom replacement.


75/96

Some of the technical features of

Circuit Breakers are:Long mechanical and

electrical operational lifeHig

h

brea

king

cap

acit

y

Overload tripping

through

accuratelycali

brat

ed

bimetal

strip

.

Short circuit tripping

through magnetic coil.Circuit breakers gives protection to the

equipments such as motors,transformers, air conditioners, refrigerators,

geysers, mixers etc. andcables/wires in electrical

distribution system.4.

O

ve

rl

o

a

d

R

el

ays

It can be defined as the device which is

operative by variation in theconditions of one electrical circuit to affect

another device in same orano

ther

elec

tric

circuit. Relays provides

overload protection overcontrol circuits when used in conjugation with

contactors and othermotor control equipments, they provide accurate

and reliable controland protection under

overload condition.5.

Co

nta

cto

rs

Device used for repeatedly establishing and

interrupting an electricpower circuit. The contactors are suitable for

controlling electricalcircuit of all kinds e.g. capacitor, lighting,

heating, switching A.C.circuit as well D.C. circuits Also suitable for

use in control panel formachine tools, motor control centers and

other applications wherehigh frequency

requirement is

must.Contactors should have

following design features:Long Life: Bounce free contact system

contributes to longcontact

life.Modern techniques of arc quenching: In

case of A.C. contactor,double breaking contact divide the arc into

two. For contactorsof higher size, deionization

chamber split the arcs inton

u

m

e

r

o

u

s

s

h

ort

a

r

c

s.


76/96

Contactors are designs for very high

frequency operationCom

pact

Size Installation: Some contactors can be

mount in any position andsome with maximum inclination, from

vertical surface, of 22 degrees.

Auxiliary Contact: For control a

interlocking purposes,contactors can be provided with a numberof auxiliary contacts.

6. Fuses

A device used for protection of equipments. A

wide range of fuses isavailable for protection of transformer, cables,

capacitors and motorsfor

applicati

on in

Air or

Oil.

HRC fuses are used for the interruption of fault

current in indoor andoutdoor high voltage system and also protection

of distribution powerequipm

ent.7.

Pr

es

su

re

S

w

itc

h

The function of pressure switch is to break or

make the control circuitwhenever the pressure actuates the switch

contacts. The switchcontacts may be normally open type which

closes on increasingpressure or of normally close type which

open on increasingpressure. Pressure switches use single pole

double throw (SPDT)micro switches as

switching

element.These switches are use with water, oil, air,

nitrogen, inert gases,steam, mineral oil

and natural gas

etc.8.

Intr

oduc

tion

toNC

Automation has been associated with

advancement in technology.The problem of automation of small lot

production have beenovercome by numerical control (NC) machine

tools have great extent.NUMERICAL

CONTROL

(NC)

is defines as

A system in

whichactions are controlled by direct insertion of

numerical data at some


77/96


78/96

times. To sense direction of rotation a two

photocell system is used.Photocell is arranged so that

output signals have 90

shifts

to

each

0

other. External logic circuitry is used to

determine the direction ofrotation.

10.

DrivesDrives refer to the system package compared to

servo amplifier andservo

motor.10

.1

S

pi

n

dl

e

dr

iv

es

The spindle drives on modern NC machines is

DC/AC drive. It is usedin combination with three or four step gear boxes

to get full power inthe entire cutting speed range. These

drives are controlled bySCR/Tr

ansistor

controll

ers.

1

0

.

2

A

x

es

D

ri

v

e

All axes are driven by DC/AC servo

drives controlled bySCR/transistors through pre-loaded balls

screw and nuts. Verticalslides are normally equipped with

hydraulic counter balance toprovide smooth servo action. As cent percent

counter balance will notalways be possible, spring set disc brake is

used on servo motor tohold the position of the vertical slide during

shut down of machine.1

0

.

3

D

.

C

M

o

t

or

A D.C. motor can be thought of

made up of two parts:1) A stationary field either of permanent

magnet or electromagnet2) An armature which

is a

Documents

22861869 Summer Training Report