EMEC LAB ORIENTATION

Importance of Electrical M/Cs

Classification of Electrical M/Cs

What do you mean by testing of

Electrical M/Cs?

How do we test them? (According to

BIS, IEC)

Experiments to be conducted in

First Cycle

O. C and S.C Tests on a Single Phase

Transformer

No load tests on a DC shunt motor

( Swinburne’s & Speed Control Test )

No load tests on a Synchronous m/c

(OC and SC test)

No load tests on a DC Shunt

generator( O.C Test & Critical Speed )

Load test on a DC Shunt generator

Circuit Diagram Exp 1

1

A

1A

1A

0-50V

50V/10A

0-10A

Circuit Diagram

1A

1A

125V/2.5A

0- 2.5A

0-125V

Use any one phase ( R/Y/B ) and neutral of three phase

Variac instead of single phase variac shown in Figs 1.3

and 1.4 for O. C and S. C test.

Keep the variac at it’s minimum position (zero) before

switching on / off the supply mains.

3 phase variac connections

Panel Details

Panel

No.

Machine

Rating

Instruments Mounted

on Panel

Fuse

Rating

Supply Expts to be

Conducted1 3 DC

1 Transformer

2KVA,

115/230V

1.Voltmeter 0- 500V

Two ( AC )

2.Ammeter 0-10A;

Two ( AC )

3.Wattmeter UPF

250V/10A –one

4.Wattmeter LPF

500V/5A –one

1A for

OC

&SC

Test

2A for

Sump-

ner’s

test

Yes Variac

(3 )

0-230V

No 1 6

16 Transformer

2KVA,

115/230V

1.Voltmeter 0-500V

Two ( AC )

2.Ammeter 0-10A

Three ( AC )

3.Wattmeter UPF

250V/10A –one

4.Wattmeter LPF

500V/5A –one

1A for

OC

&SC

Test

2A for

Sump-

ner’s

test

Yes Variac

( 3 )

0-230V

No 1 6

Keep Ra (ext) at it’s maximum value while switching

ON / OFF the DC supply mains

Do not switch OFF the supply mains until the two tests

are over (Swinburne’s & speed control Tests).

Circuit Diagram Exp 2

7A

7A

272Ω/1.7A0-2A

0-5A

0-250V

90Ω / 5A

+

+

+

Measure Ra at the end only

?

Circuit Diagram for

measurement of Ra

V

Panel

No.

Machine

Rating

Instruments

Mounted on

Panel

Fuse

Rating

Supply Expts to

be

Conduc-

ted

1 3 DC

19 DC shunt

motor,

220V, 46A,

9 KW, 1120-

1500rpm

1.Voltmeter DC

0-250V -one

2.Ammeter 0-10A

one( DC )

2.Ammeter 0-2A -

one( DC )

7A Yes No Yes 2

22 DC shunt

motor,

220V,

56.5A,

13KW,

1400rpm

1.Voltmeter DC

0-250V -one

2.Ammeter 0-10A –

one( DC )

2.Ammeter 0-2A –

one ( DC )

7A Yes No Yes 2

Panel Details

Circuit Diagram Exp 3

Modification required in exciter circuit for panel 10

( Input at X1 and X2 )

80 A

80A 100Ω/2A

2A

2A676Ω/1.7A 0-2A

0-60Hz

0-500V

0-15A

Panel No 9

+

80A

80A100Ω / 2A

2A

2A

0-2A

676Ω/1.2A

0-60Hz

0-500V

SC Test

Panel No 9

80A

80A

2A

2A

0-2A

676Ω/1.2A

100Ω/2A

0-15A

Note: Fuse rating of DC motor is 55A for panel No.10

Modified exciter circuit for panel 10

Fig 3.3.A

Connection diagram for 4 point starter at panel 10

L

Fig 3.3.B

In SC test draw the table between If v/s Isc

Panel

No.

Machine

Rating

Instruments

Mounted on

Panel

Fuse

Rating

Supply Expts

To be

Condu-

cted

1 3 DC

9 Alternator

Coupled with

DC shunt Gen

Alternator:

10KVA, 440V,

1000rpm,

13.2A

50Hz, 3,

0.8pf

Excit. Volts

220V

Excit. Amps

2A

DC Motor-

20BHP, 220V,

950rpm,79.8A

1.Voltmeter AC

0-500V –one

2.Ammeter AC

0-20A -one

3.Freq meter

0-60Hz -one

4. Voltmeter DC

0-250V -one

5. Ammeter DC

0-15A -one

6. Ammeter DC

0-2A -one

(3 point Starter)

80A Yes Yes Yes 3 8

Panel Details

10 Synchronous

M/C 3

Motor, /,

231V/400V,

39/22.5A, 11KW,

0.82,pf, 1450 rpm

3 motor, /,

231V/400V,

22/12.7A,7.5KW

UPF, 1450rpm

3,

Generator,,

400V,10.8A,

7.5KVA,0.8pf,

1500rpm,50c/s.

Excit.21V

DC motor, 220V,

52.5A, 10KW,

1500rpm

DC Generator,

175V, 57A,

10KW,1450rpm

1.Voltmeter AC

0-500V –one

2.Ammeter AC

0-25A -one

(ANALOG to be

connected)

3.Freq meter

0-60Hz -one

4. Voltmeter DC

0-250V -one

5. Ammeter DC

0-20A -one

6. Ammeter DC

0-10A -one

(4point Starter)

Synchroscope-one

55A Yes Yes Yes

21V

25A

for

Exciter

3 8

Panel Details

Circuit Diagram ( OCC)

Fig 4.1

7A

7A

272Ω /1.7A

100Ω /5A

2A

2A272Ω /1.7A

0-2A

0-250V

Panel No 2

Note: For Panel number 5 Voltmeter range is 0-300V

Circuit Diagram ( Critical Speed )

Fig 4.2

Add one more double barrel rheostat in series with Ra

(ext) to bring down the motor speed to nearly 300 rpm in

the circuit diagram (Fig 4.2 of Lab manual)

Connect an 0-2 A DCammeter in generator field circuit

(not shown in manual)

A

5A

5A

272Ω /1.7A

100Ω /5A

272Ω/1.7A

0-250 V

0-2A

Panel No 2

Note: Generator side FR is 570Ω/1.2A

for panel No 5

a

Panel

No.

Machine

Rating

Instruments

mounted on

Panel

Fuse

Rating

Supply Expts to be

conducted

1 3 DC

2 DC motor

Generator set

(coupled)

Motor-230V,

28A, 5.5KW,

1450 rpm

Generator-

160V, 29A,

4.65KW

1450rpm

1.Voltmeter DC

0-250V –one

2.Ammeter DC

0-2A -one

5A Yes No Yes 4

5 DC motor

Generator set

(coupled)

Motor-220V,

20.3A,5H.P,

1450 rpm

Gen- 220V,

11.8A, 2.6KW

1450rpm

1.Voltmeter DC

0-250V –one

2.Ammeter DC

0-2A -one

(3point starter,

not to be

used)

5A Yes No Yes 4

Panel Details

Circuit Diagram (Load test on DC Gen. )

Fig 5.1

At panel 4 use four point starter (as shown in Fig 3.3.B)

At panel 4 connect a additional loading unit if required

NOTE: Ammeter on source-side of motor not required.

15A

15A0-250V

0-15A15A

15A

0-250V

0-2A

272Ω /1.7A

Note: For panel No4 take 25A in place of 15A at all points

280Ω /1.8A

Panel No. 6

Panel

No.

Machine

Rating

Instruments

Mounted on

Panel

Fuse

Rating

Supply Expts

to be

Condu

cted1 3 DC

4 DC motor gen

set (coupled)

Motor-220V,

21A,3.8KW,

5.2H.P,1070-

1450rpm

Gen-230V,

20.8A,4.8KW

1450 rpm

1 Voltmeter DC

0-500V –one

2. Ammeter DC

0-20A -two

3. Ammeter DC

0-2A -two

(4 point starter)

21A Yes No Yes 5 7

6 DC motor gen

set (identical)

220V, 12.8A,

2.2KW, 3 HP,

1450 rpm

1 Voltmeter DC

0-500V –one

2. Ammeter DC

0-20A -two

3. Ammeter DC

0-2A -two

(3 point starter)

15A Yes No Yes 5 7

Panel Details

Some Questions Related to every

Experiment

Objective

Instruments Used

Supply [AC (1 or 3 Phase) or DC or Both]

Machines

You are supposed to come prepared for expts,

the circuit diagram given in manual must be

labeled properly

Every Batch will submit a lab

report containing the following

1) Aim of the experiment

2) Observation Table

3) Calculations/graph

4) Comments on results & precautions

5) Draw the Neat Labeled Physical

Layout after the each Experiment.

Some Rule and Regulation of this Lab

Be punctual

Always wear shoes with rubber sole

Do not wear lose clothes

DO not touch any live terminals or wires

Beware of dynamics of machinery and consciously keep a distance

Before switching on the supply make sure that there is NO LOOSE CONNECTION and get your connections approved by the instructor

After completing the experiment, disconnect the circuit and keep the wires at the proper place

Connection diagram for 4 point starter

Fig 3.3 B

L

• Note: 1. Mark the DC Machines /

Instruments with proper polarity.

2. DC Machines on panel number

4 and 10 have four point starter.