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M.A.M SCHOOL OF ENGINEERINGTRICHY 621 105.

DEPARTMENT OF EEE

LAB MANUAL

CLASS : II YEAR MECHANICALSEMESTER : III SEMSUBJECT CODE : EE1206SUBJECT :ELECTRICAL ENGINEERING LABORATORY

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EE 1206 ELECTRICAL ENGINEERING LABORATORY

2

LIST OF EXPERIMENTS

S.NO NAME OF THE EXPERIMENT PAGENUMBER

1 Load test on DC Shunt & DC Series motor

2 O.C.C & Load characteristics of DC Shunt and DC Series generator

3 Speed control of DC shunt motor (Armature, Field control)

4 Load test on single phase transformer

5 O.C & S.C Test on a single phase transformer

6 Regulation of an alternator by EMF & MMF methods.

7 V curves and inverted V curves of synchronous Motor

8 Load test on three phase squirrel cage Induction motor

9 Speed control of three phase slip ring Induction Motor

10 Load test on single phase Induction Motor.

11 Study of DC & AC Starters

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Ex.No.1 1.A.LOAD TEST ON DC SHUNT MOTOR

AIM:

To conduct load test on DC shunt motor and to find efficiency.

APPARATUS REQUIRED:

S.No. Apparatus Range Type Quantity

1 Ammeter (0-20)A MC 1

2 Voltmeter (0-300)V MC 1

3 Rheostat 1250 , 0.8A Wire Wound 1

4 Tachometer (0-1500) rpm Digital 1

5 Connecting Wires 2.5sq.mm. Copper Few

PRECAUTIONS:

1. DC shunt motor should be started and stopped under no load condition.

2. Field rheostat should be kept in the minimum position.

3. Brake drum should be cooled with water when it is under load.

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TABULAR COLUMN:

S.No.Voltage

V(Volts)

CurrentI

(Amps)

Spring Balance Reading

(S1 S2)KgSpeed

N(rpm)

TorqueT

(Nm)

OutputPower

Pm

(Watts)

InputPower

Pi

(Watts)

Efficiency%S1(Kg) S2(Kg)

Circumference of the Brake drum = cm

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PROCEDURE:

1. Connections are made as per the circuit diagram.

2. After checking the no load condition, and minimum field rheostat position, DPST switch is closed and starter resistance is gradually removed.

3. The motor is brought to its rated speed by adjusting the field rheostat.

4. Ammeter, Voltmeter readings, speed and spring balance readings are noted under no load condition.

5. The load is then added to the motor gradually and for each load, voltmeter, ammeter, spring balance readings and speed of the motor are noted.

6. The motor is then brought to no load condition and field rheostat to minimum position, then DPST switch is opened.

FORMULAE:

Circumference

Radius = ------------------- m

100 x2 Torque T = (S1 S2) x R x 9.81 Nm

Input Power Pi = VI Watts

2 NT

Output Power Pm = ------------ Watts

60

Output Power

Efficiency % = -------------------- x 100%Input Power

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MODEL GRAPHS:

S p e e d

N ( r p m

)

y

x

Torque T (Nm)

S p e e d

N ( r p m

)

T o r q u e

T ( N m

)

E f f i c i e n c y

%

N

T

y3 y2 y1

Out ut Power Watts

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RESULT:

Thus load test on DC shunt motor is conducted and its efficiency is determined.

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1.B.LOAD TEST ON DC SERIES MOTOR

AIM:

To conduct load test on DC Series Motor and to find efficiency.

APPARATUS REQUIRED:






PRECAUTIONS:

1. The motor should be started and stopped with load

2. Brake drum should be cooled with water when it is under load.

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TABULAR COLUMN:

S.No.Voltage

V(Volts)

CurrentI

(Amps)

Spring BalanceReading

(S1 S2)KgSpeed

N(rpm)

TorqueT

(Nm)

OutputPower

Pm

(Watts)

InputPower

Pi

(Watts)

Efficiency%S1(Kg) S2(Kg)

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PROCEDURE:


2. After checking the load condition, DPST switch is closed and starter resistance is gradually removed.

3. For various loads, Voltmeter, Ammeter readings, speed and spring balance readings are noted.

4. After bringing the load to initial position, DPST switch is opened.

FORMULAE:

Circumference

R = ------------------- m

100 x2

Torque T = (S1 S2) x R x 9.81 Nm

Input Power Pi = VI Watts

2 NT

Output Power Pm = ------------ Watts

60

Output Power

Efficiency % = -------------------- x 100%

Input Power

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MODEL GRAPH:

T o r q u e

T ( N m

)

S p e e d

N ( r p m

)

E f f i c i e n c y

%

y3 y2 y1

Out ut Power Watts

N

E

T

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RESULT:

Thus load test on DC series motor is conducted and its efficiency is determined.

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EX.NO : 2 2.A.OPEN CIRCUIT CHARACTERISTICS OF SELF EXCITED

DC SHUNT GENERATOR

AIM:

To obtain open circuit characteristics of self excited DC shunt generator and to find its critical resistance.

APPARATUS REQUIRED:




3 Rheostats 1250 , 0.8A Wire Wound 2

4 SPST Switch - - 1

5 Tachometer (0-1500)rpm Digital 1


PRECAUTIONS:

1. The field rheostat of motor should be in minimum resistance position at the time of starting and stopping the machine.

2. The field rheostat of generator should be in maximum resistance position at the time of starting and stopping the machine.

3. SPST switch is kept open during starting and stopping.

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TABULAR COLUMN:

S.No.Field Current

If (Amps)

Armature Voltage

Eo (Volts)

MODEL GRAPH:

Eo

If

Critical Resistance = E o / I f Ohms E o

( V o l

t s )

If (Amps)

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PROCEDURE:


2. After checking minimum position of motor field rheostat, maximum position of generator field rheostat, DPST switch is closed and starting resistance is gradually

removed.

3. By adjusting the field rheostat, the motor is brought to rated speed.

4. Voltmeter and ammeter readings are taken when the SPST switch is kept open.

5. After closing the SPST switch, by varying the generator field rheostat, voltmeter and ammeter readings are taken.

6. After bringing the generator rheostat to maximum position, field rheostat of motor to minimum position, SPST switch is opened and DPST switch is opened.

RESULT:

Thus open circuit characteristics of self excited DC shunt generator are obtained and its critical resistance is determined.

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2.B.LOAD CHARACTERISTICS OF SELF EXCITED

DC SHUNT GENERATOR

AIM:To obtain internal and external characteristics of DC shunt generator.

APPARATUS REQUIRED:


1 Ammeter (0-2)A

(0-20) A

MC

MC

1

1

2 Voltmeter (0-300)V MC 13 Rheostats 1200 , 0.8A Wire Wound 2

4 Loading Rheostat 5KW, 230V - 1



PRECAUTIONS:

1. The field rheostat of motor should be at minimum position.2. The field rheostat of generator should be at maximum position.

3. No load should be connected to generator at the time of starting and stopping.

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DETERMINATION OF ARMATURE RESISTANCE:

S.No.Field Current

If (Amps)

Load Current

IL (Amps)

Terminal Voltage

(V) Volts

Ia = IL + If

(Amps)Eg =V + Ia Ra

(Volts)

DPST

SW

ITCH

+

-

-+

(0-300)VMC

(0-20)AMC

Fuse

Fuse

A1

A2

27A

27A

LOAD5 KW, 230V

G

A

V220VDC

Supply

+

-

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PROCEDURE:


2. After checking minimum position of DC shunt motor field rheostat and maximum position of DC shunt generator field rheostat, DPST switch is closed and starting

resistance is gradually removed.

3. Under no load condition, Ammeter and Voltmeter readings are noted, after bringing the voltage to rated voltage by adjusting the field rheostat of generator.

4. Load is varied gradually and for each load, voltmeter and ammeter readings are noted.

5. Then the generator is unloaded and the field rheostat of DC shunt generator is brought to maximum position and the field rheostat of DC shunt motor to minimum

position, DPST switch is opened.

FORMULAE:

Eg = V + Ia Ra (Volts)

Ia = IL + If (Amps)

Eg : Generated emf in Volts

V : Terminal Voltage in Volts

Ia : Armature Current in Amps

IL : Line Current in Amps

If : Field Current in Amps

Ra : Armature Resistance in Ohms

PROCEDURE TO FIND ARMATURE RESISTANCE :

1. Connections are made as per the circuit diagram.2. Supply is given by closing the DPST switch.

3. Readings of Ammeter and Voltmeter are noted.

4. Armature resistance in Ohms is calculated as Ra = (Vx1.5) /I

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TABULAR COLUMN:

S.No. Voltage

V (Volts)

Current

I (Amps)

Armature Resistance

Ra (Ohms)

MODEL GRAPH:

V L , E

V o l

t s

If , IL (Amps)

V Vs I L (Ext Char)

E Vs I L (Int Char)

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RESULT:

Thus the load characteristics of self excited DC shunt generator is obtained.

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Ex.No.2 2.C.OPEN CIRCUIT CHARACTERISTICS OF DC SERIES GENERATOR

AIM:

To obtain open circuit characteristics of separately excited DC shunt generator.

APPARATUS REQUIRED:







PRECAUTIONS:

1. The field rheostat of motor should be in minimum resistance position at the time of starting and stopping the machine.

2. The field rheostat of generator should be in maximum resistance position at the time of starting and stopping the machine.

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E o

( V o l

t s )

If (Amps)

TABULAR COLUMN:

S.No.Field Current

If (Amps)

Armature Voltage

Eo (Volts)

MODEL GRAPH:

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PROCEDURE:


2. After checking minimum position of motor field rheostat, maximum position of generator field rheostat, DPST switch is closed and starting resistance is gradually

removed.

3. By adjusting the field rheostat, the motor is brought to rated speed.

4. By varying the generator field rheostat, voltmeter and ammeter readings are taken.

5. After bringing the generator rheostat to maximum position, field rheostat of motor to minimum position, DPST switch is opened.

RESULT: Thus open circuit characteristics of separately excited DC shunt generator is obtained.


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2.D.LOAD CHARACTERISTICS OF DC SERIES GENERATOR

AIM:

To obtain internal and external characteristics of DC separately excited DC shunt generator.

APPARATUS REQUIRED:


1 Ammeter (0-2)A

(0-20) A

MC

MC

1

1



4 Loading Rheostat 5KW, 230V - 1



PRECAUTIONS:

1. The field rheostat of motor should be at minimum position.

2. The field rheostat of generator should be at maximum position.

3. No load should be connected to generator at the time of starting and stopping.


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DETERMINATION OF ARMATURE RESISTANCE:

TABULAR COLUMN:S.No. Voltage

V (Volts)

Current

I (Amps)

Armature Resistance

Ra (Ohms)

D

PST

SWITCH

+

-

-+

(0-300)VMC

(0-20)A

MC

Fuse

Fuse

A1

A2

27A

27A

LOAD5 KW, 230V

G

A

V220VDC

Supply

+

-


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PROCEDURE:


2. After checking minimum position of DC shunt motor field rheostat and maximum position of DC shunt generator field rheostat, DPST switch is closed and starting

resistance is gradually removed.

3. Under no load condition, Ammeter and Voltmeter readings are noted, after bringing the voltage to rated voltage by adjusting the field rheostat of generator.

4. Load is varied gradually and for each load, voltmeter and ammeter readings are noted.

5. Then the generator is unloaded and the field rheostat of DC shunt generator is brought to maximum position and the field rheostat of DC shunt motor to minimum

position, DPST switch is opened.

PROCEDURE TO FIND ARMATURE RESISTANCE :


2. Supply is given by closing the DPST switch.3. Readings of Ammeter and Voltmeter are noted.

4. Armature resistance in Ohms is calculated as Ra = (Vx1.5) /I


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TABULAR COLUMN:

MODEL GRAPH:

S.No.Field Current

If (Amps)

Load Current

IL (Amps)

Terminal Voltage

(V) Volts

Ia = IL + If

(Amps)Eg =V + Ia Ra

(Volts)

V L E

V o l

t s

If , IL (Amps)

V Vs I L (Ext Char)

E Vs I L (Int Char)


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FORMULAE:

Eg = V + Ia Ra (Volts)

Ia = IL + If (Amps)

Eg : Generated emf in Volts

V : Terminal Voltage in Volts

Ia : Armature Current in Amps

IL : Line Current in Amps

If : Field Current in Amps

Ra : Armature Resistance in Ohms

RESULT: Thus load characteristics of separately excited DC shunt generator is obtained.


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Ex.No : 3 SPEED CONTROL OF DC SHUNT MOTOR

AIM:

To obtain speed control of DC shunt motor by

Varying armature voltage with field current constant. Varying field current with armature voltage constant

APPARATUS REQUIRED:


1 Ammeter (0-20) A MC 1

2 Voltmeter (0-300) V MC 1

3 Rheostats1250 , 0.8A

50 , 3.5A

Wire

WoundEach 1



PRECAUTIONS:

1.

Field Rheostat should be kept in the minimum resistance position at the time of starting and stopping the motor.2. Armature Rheostat should be kept in the maximum resistance position at the time of starting and stopping the motor.


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TABULAR COLUMN:

(i) Armature Voltage Control:

S.No.

If1 = If2 = If3 =

Armature

Voltage

Va ( Volts)

Speed

N (rpm)

Armature

Voltage

Va ( Volts)

Speed

N (rpm)

Armature

Voltage

Va ( Volts)

Speed

N (rpm)

(ii) Field Control:

S.No.

Va1 = Va2 = Va3 =

Field

Current

If (A)

Speed

N (rpm)

Field

Current

If (A)

Speed

N (rpm)

Field

Current

If (A)

Speed

N (rpm)


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PROCEDURE:


2. After checking the maximum position of armature rheostat and minimum position of field rheostat, DPST switch is closed

(i) Armature Control:

1. Field current is fixed to various values and for each fixed value, by varying the armature rheostat, speed is noted for various voltages across the armature.

(ii) Field Control:1.Armature voltage is fixed to various values and for each fixed value, by adjusting

the field rheostat, speed is noted for various field currents.

2.Bringing field rheostat to minimum position and armature rheostat to maximum

position DPST switch is openedRESULT:

Thus the speed control of DC Shunt Motor is obtained using Armature and Field control methods.


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MODEL GRAPHS:

S p e e d

N ( r p m

)

S p e e d

N ( r p m

)

If (Amps)Va (Volts)

If1

If3

If2

Va3

Va1

Va2


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Result :

Thus the speed control of DC shunt motor by Varying armature voltage with field current constant Varying field current with armature voltage constant

was done.


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EE 1206 ELECTRICAL ENGINEERING LABORATORYE N 4 LOAD TEST ON A SINGLE PHASE TRANSFORMER

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Ex.No.4 LOAD TEST ON A SINGLE PHASE TRANSFORMER

AIM:

To conduct load test on single phase transformer and to find efficiency and percentage regulation.

APPARATUS REQUIRED:


1 Ammeter (0-10)A

(0-5) A

MI

MI

1

1

2 Voltmeter (0-150)V

(0-300) V

MI

MI

1

1

3 Wattmeter (300V, 5A)

(150V, 5A)

Upf

Upf

1

1

4 Auto Transformer 1 , (0-260)V - 1

5 Resistive Load 5KW, 230V - 1

6 Connecting Wires 2.5sq.mm Copper Few

PRECAUTIONS:

1. Auto Transformer should be in minimum position.

2. The AC supply is given and removed from the transformer under no load condition.

EE 1206 ELECTRICAL ENGINEERING LABORATORYTABULAR COLUMN:

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TABULAR COLUMN:

S.No. LoadPrimary Secondary Input

Power W1 x MF

OutputPower

W2 x MF

Efficiency

%

%RegulationV1

(Volts)I1

(Amps)W1

(Watts)V2

(Volts)I2

(Amps)W2

(Watts)


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PROCEDURE:


2. After checking the no load condition, minimum position of auto transformer and DPST switch is closed.

3. Ammeter, Voltmeter and Wattmeter readings on both primary side and secondary side are noted.

4. The load is increased and for each load, Voltmeter, Ammeter and Wattmeter readings on both primary and secondary sides are noted.5. Again no load condition is obtained and DPST switch is opened.

FORMULAE:

Output Power = W2 x Multiplication factor

Input Power = W1 x Multiplication factor

Output Power

Efficiency % = -------------------- x 100%Input Power

VNL- VFL(Secondary)

Regulation R % = ------------------------------ x 100%

VNL


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MODEL GRAPHS:

E f f i c i e n c y

%

R e g u l a t

i o n

R %

R

Output Power (Watts)


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RESULT:

Thus the load test on single phase transformer is conducted.


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EX.NO: 5 OPEN CIRCUIT & SHORT CIRCUIT TEST ON A

SINGLE PHASE TRANSFORMER

AIM:

To predetermine the efficiency and regulation of a transformer by conducting open circuit test and short circuit test and to draw equivalent circuit.

APPARATUS REQUIRED:


1 Ammeter (0-2)A

(0-5) A

MI

MI

1

1

2 Voltmeter (0-150)V MI 2

3 Wattmeter (150V, 5A)

(150V, 5A)

LPF

UPF

1

1

4 Connecting Wires 2.5sq.mm Copper Few

PRECAUTIONS:

1. Auto Transformer should be in minimum voltage position at the time of closing & opening DPST Switch.

PROCEDURE:

OPEN CIRCUIT TEST:


2. After checking the minimum position of Autotransformer, DPST switch is closed.


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EE 1206 ELECTRICAL ENGINEERING LABORATORY3. Auto transformer variac is adjusted get the rated primary voltage.

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4. Voltmeter, Ammeter and Wattmeter readings on primary side are noted.

5. Auto transformer is again brought to minimum position and DPST switch is opened.

SHORT CIRCUIT TEST:


2. After checking the minimum position of Autotransformer, DPST switch is closed.3. Auto transformer variac is adjusted get the rated primary current.

4. Voltmeter, Ammeter and Wattmeter readings on primary side are noted.

5. Auto transformer is again brought to minimum position and DPST switch is opened.

EE 1206 ELECTRICAL ENGINEERING LABORATORYTABULAR COLUMN:

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OPEN CIRCUIT TEST:

Vo

(Volts)

Io

(Amps)

Wo

(Watts)

SHORT CIRCUIT TEST:

Vsc

(Volts)

Isc

(Amps)

Wsc

(Watts)

EE 1206 ELECTRICAL ENGINEERING LABORATORYFORMULAE:

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Core loss: Wo = VoIo cos o

Wo Wo

cos o = ------- o = cos-1 -------

Vo Io Vo Io

I = Io cos o (Amps) I = Io sin o (Amps)

V0 R o = -------

I

V0 Xo = -------

I

W sc R o2 = -------

Isc2

Vsc Zo2 = -------

Isc

Xo2 = ( Z o2 - R o2

2)1/2

R 02 R o1 = -------

K 2

X02 Xo1 = -------

K 2

V2 K= ------- = 2

V1

EE 1206 ELECTRICAL ENGINEERING LABORATORYPercentage Efficiency: for all loads and p.f.

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Output Power (X) x KVA rating x 1000 x cos

Efficiency % = -------------------- = ------------------------------------------------

Input Power Output power + losses

(X) x KVA rating x 1000 x cos

= -------------------------------------------------------------

(X) x KVA rating x 1000 x cos + Wo + X2Wsc

Percentage Regulation:

(X) x Isc (Ro2 cos Xo2sin ) x 100

R% = --------------------------------------V2

Where X is the load and it is 1 for full load, for half load, load, load etc.. and the power factor is, upf, o.8 p.f lag and 0.8 p.f lead

+ = lagging

- = leading


EQUIVALENTCIRCUIT

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EQUIVALENTCIRCUIT:

ZL = Z L/K 2

Xo1R o1

R o Xo

Vo

Io

ISCoR

N

LOAD

EE 1206 ELECTRICAL ENGINEERING LABORATORYMODEL GRAPHS:

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E f f i c i e n c

%

Output power (Watts)

Power factor

% lagging

% leading


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RESULT:

Thus the efficiency and regulation of a transformer is predetermined by conducting open circuit test and short circuit test and the equivalent circuit is drawn.


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EX NO : 6 A REGULATION OF THREE PHASE ALTERNATOR BY EMF METHOD

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EX.NO : 6.A REGULATION OF THREE PHASE ALTERNATOR BY EMF METHOD

DATE :

AIM :To predetermine the regulation of an alternator at full load at different power factor (zero p.f , lag , lead) by EMF method.

NAME PLATE DETAILS :

Three phase Alternator DC shunt motor 1.2.3.4.APPARATUS REQUIRED :

S.NO APPARATUS RANGE TYPE QUANTITY

1 Ammeter (0 - 2.5) A MC 12 Ammeter (0 - 10) A MI 13 Voltmeter (0 - 600) V MI 14 Rheostat 350 ,1.5A Wire wound 1

5 Rheostat 1000 ,1.5A Wire wound 1

6 Tachometer ----- Digital 17 Connecting wires ----- ----- As required

FUSE RATING : 125 % of rated current (full load current)For DC shunt motor:

For Alternator:


OPEN CIRCUIT TEST :

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OPEN CIRCUIT TEST :

S.NO Field current (I f )in amps

Open circuit lineVoltage(V OL ) in volts

Open circuit phase Voltage(VOP = V OL /3) in volts

12

3456

SHORT CIRCUIT TEST :


Short circuit current (I sc)in amps

1

234

GRAPH :


FORMULAE :

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FORMULAE :

1. Armature resistance (R a) = ___________________ (Given data )2. Synchronous impedance (Z s) = (V ph / Isc ) ---------- ( From the graph)

Where V ph Phase voltage in voltsIsc Short circuit current

3. Synchronous reactance (X s) = [ Z s2

R a2

]1/2

Where R a - Armature resistance4. Open circuit voltage (Eo) = [ ( V ratedcos + IaR a )2 + ( V ratedsin + IaXs ) 2 ] 1/ 2

(For lagging power factor)5. Open circuit voltage (Eo) = [ ( V ratedcos + IaR a )2 + ( V ratedsin- IaXs ) 2 ] 1/ 2

(For leading power factor)6. Open circuit voltage (Eo) = [ ( V rated + I aR a )

2 + ( I aXs )2 ] 1/ 2

(For unity power factor)7. Percentage regulation = [(Eo - V rated) / V rated ] x 100

PROCEDURE :

1. The connections are made as per the circuit diagram.2. Switch on the DC supply.3. The motor is started with the help of 3 point starter.4. The field rheostat in the motor side is adjusted up to the motor attains the rated speed.5. The field rheostat in the alternator side is varied and note down the field current and voltage readings.6. After the open circuit readings are noted, the excitation of alternator is reduced.7. The TPST switch is closed.8. The field rheostat in the alternator side is gradually increased till the short circuit current reached at the rated current of an alternator and the field current

and short circuit current readings are noted.9. The supply is switched off and the graph is drawn.


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RESULTANT TABULATION FOR REGULATION OF 3 PHASE ALTERNATOR BY EMF METHOD:

S.NO Percentage of regulationPower factor Lagging Leading Unity

1 0.2 ---2 0.4 ---3 0.6 ---4 0.8 ---5 1.0 ---

GRAPH :

EE 1206 ELECTRICAL ENGINEERING LABORATORYPROCEDURE TO DRAW THE GRAPH FOR EMF METHOD :

1 Draw the open circuit characteristics curve (Generated voltage per phase Vs Field current)

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1. Draw the open circuit characteristics curve.(Generated voltage per phase Vs Field current)2. Draw the short circuit characteristics curve.( Short circuit current Vs Field current)3. From the graph find the open circuit voltage per phase for the rated short circuit current.4. By using respective formulae find the Z s, X s, Eo and percentage regulation.

RESULT :

Thus the regulation of an alternator was predetermined by EMF method.


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EE 1206 ELECTRICAL ENGINEERING LABORATORYEX.NO : 6.B REGULATION OF THREE PHASE ALTERNATOR BY MMF METHODDATE :

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AIM :To predetermine the regulation of an alternator at full load at different power factor ( zero p.f , lag , lead) by MMF method.


Three phase Alternator DC shunt motor1.2.3.4.

APPARATUS REQUIRED :

S.NO APPARATUS RANGE TYPE QUANTITY1 Ammeter (0 - 2.5) A MC 12 Ammeter (0 - 10) A MI 13 Voltmeter (0 - 600) V MI 14 Rheostat 350 ,1.5A Wire wound 1

5 Rheostat 1000 ,1.5A Wire wound 1

6 Tachometer ----- Digital 17 Connecting wires ----- ----- As required

FUSE RATING : 125 % of rated current (full load current)

For DC shunt motor :

For Alternator :


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OPEN CIRCUIT TEST :


Open circuit lineVoltage(V OL ) in volts

Open circuit phase Voltage(VOP = V OL /3) in volts

1

23456

SHORT CIRCUIT TEST :


Short circuit current (I sc)in amps

1234

MODEL GRAPH FOR MMF METHOD :


PROCEDURE :

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1. The connections are made as per the circuit diagram.2. Switch on the DC supply.3. The motor is started with the help of 3 point starter.4. The field rheostat in the motor side is adjusted up to the motor attains the rated speed.5. The field rheostat in the alternator side is varied and note down the field current and voltage readings.6. After the open circuit readings are noted, the excitation of alternator is reduced.7. The TPST switch is closed.8. The field rheostat in the alternator side is gradually increased till the short circuit current reached at the rated current of an alternator and the field current

and short circuit current readings are noted.9. The supply is switched off and the graph is drawn.

PROCEDURE TO DRAW THE GRAPH FOR MMF METHOD :

1.

Draw the open circuit characteristics curve.(Generated voltage per phase Vs Field current)2. Draw the short circuit characteristics curve.( Short circuit current Vs Field current)3. From the graph find the open circuit voltage per phase for the rated short circuit current.4. By using respective formulae find the Z s,Xs,Eo and percentage regulation.


RESULTANT TABULATION FOR REGULATION OF 3 PHASE ALTERNATOR BY MMF METHOD:

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S.NO Percentage of regulationPower factor Lagging Leading Unity

1 0.2 ---2 0.4 ---3 0.6 ---4 0.8 ---5 1.0 ---

GRAPH :


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RESULT :

Thus the regulation of an alternator was predetermined by MMF method.


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EE 1206 ELECTRICAL ENGINEERING LABORATORYEX.NO : 7 LOAD TEST ON 3 PHASE SQUIRREL CAGE INDUCTION MOTOR DATE :

AIM :

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AIM :To conduct the load test on 3 phase squirrel cage induction motor and draw its performance characteristics.


INDUCTION MOTOR AUTO TRANSFORMER 1.2.3.4.


S.NO APPARATUS RANGE TYPE QUANTITY1 Ammeter (0 - 10) A MI 12 Voltmeter (0 - 600) V MI 13 Watt meter 600V , 10 A UPF4 Tachometer ----- Digital 15 Connecting wires ----- ----- As required



TABULATION FOR LOAD TEST ON 3 PHASE SQUIRREL CAGE INDUCTION MOTOR

R di f h b k d M l i li i f f 1

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Radius of the brake drum : ______________ m Multiplication factor of wattmeter 1 : _______ Multiplication factor of wattmeter 2 : _______

S.no LoadCurrent(I L)

LoadVoltage(V L)

Watt meterreadings

InputPower( W )

Speedof the

motor

( N )

Spring balance readings Torque( T )

OutputPower

Efficiency( )

Slip( S )

PowerFactor( cos)

W 1 W 2 W 1 + W 2 S1 S2 S S 2

Amps Volts Watt Watts Watts R.p.m Kg Kg Kg N m Watts % %

1

2

3

4

5

6

7

8


FORMULAE :Input power (P in) = W 1 + W 2 in watts.

h d d

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Where, W 1 and W 2 are watt meter readingsOutput power (P out) = ( 2 N T / 60 ) in watts. Where,

N Rotor speed in r.p.m.T (Torque) = [9.81 x ( S 1 S2 ) x R] in N.mWhere R Radius of the brake drumS1 and S 2 spring balance readings in Kg.Percentage Slip (%S) = [ (Ns N) / Ns ] x 100Where , Ns Synchronous speed N - Speed of the motor in r.p.mPower factor (Cos ) = Pin / (3 x V x I ) Where V Supply voltage in voltsI Supply current in ampsPercentage efficiency = ( P out Pin) x 100

EE 1206 ELECTRICAL ENGINEERING LABORATORYGRAPH :

(1) Power output Vs Efficiency (2) Power output Vs Torque(3) Power output Vs Speed (4) Power output Vs Line current

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(5) Power output Vs Power factor (6) Power output Vs Slip


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RESULT :

Thus the load test on 3 phase squirrel cage induction motor was conducted and its performance characteristics were drawn.


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EE 1206 ELECTRICAL ENGINEERING LABORATORYEX.NO : 8 LOAD TEST ON SINGLE PHASE INDUCTION MOTOR(SQUIRREL CAGE)DATE :

AIM :

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To conduct the load test on single phase induction motor (squirrel cage) and draw its performance characteristics.


INDUCTION MOTOR AUTO TRANSFORMER

1.

2.

3.

4.APPARATUS REQUIRED :



EE 1206 ELECTRICAL ENGINEERING LABORATORYTABULATION FOR LOAD TEST ON SINGLE PHASE INDUCTION MOTOR

Radius of the brake drum : ______________ m Multiplication factor of wattmeter 1 : _______ Multiplication factor of wattmeter 2 : _______

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S.no LoadCurrent(I L)

LoadVoltage(V L)

InputPower( W )

Speedof the

motor( N )

Spring balance readings Torque( T )

OutputPower

Efficiency( )

Slip( S )

PowerFactor( cos)

W S 1 S2 S S 2 Amps Volts Watts r.p.m Kg Kg Kg N m Watts % %

1

2

3

4

5

6

7

8


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FORMULAE :Input power (P in) = Watt meter reading (W) in watts.Output power (P out) = ( 2 NT / 60 ) in watts.Where,

N Rotor speed in r.p.m.T (Torque) = [9.81 x ( S 1 S2 ) x R] in N.mWhere R Radius of the brake drumS1 and S 2 spring balance readings in Kg.Percentage Slip (%S) = [ (Ns N) / Ns ] x 100Where , Ns Synchronous speed N - Speed of the motor in r.p.mPower factor (Cos ) = Pin / ( V x I )Where V Supply voltage in voltsI Supply current in ampsPercentage efficiency (% ) = ( P out Pin) x 100

PROCEDURE :

1. The connections are given as per the circuit diagram.2. The A.C supply is given to the motor by closing the DPST switch.3. Single phase variac is adjusted from zero to rated voltage.4. Load is applied gradually up to the rated value of the load current and the corresponding meter readings are noted.5. After note down the reading , load and variac is brought to its initial position.6. Now switch off the A.C supply which is given to the motor.

RESULT :

Thus the load test on single phase squirrel cage induction motor was conducted and its performance characteristics were drawn.


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EE 1206 ELECTRICAL ENGINEERING LABORATORYEX.NO : 9 SPEED CONTROL OF THREE PHASE SLIP RING INDUCTION MOTOR DATE :

AIM :To control the speed of three phase slip ring induction motor and draw its performance characteristics

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To control the speed of three phase slip ring induction motor and draw its performance characteristics.

NAME PLATE DETAILS :INDUCTION MOTOR AUTO TRANSFORMER

1.2.3.4.APPARATUS REQUIRED :

S.NO APPARATUS RANGE TYPE QUANTITY1 Ammeter (0 - 10) A MI 12 Voltmeter (0 - 600) V MI 13 Watt meter 600V , 10 A UPF4 Tachometer ----- Digital 1

5 Connecting wires ----- ----- As required


PROCEDURE :

1. The connections are given as per the circuit diagram.2. The A.C supply is given to the motor by closing the TPST switch.3. Initially resistance of the rotor resistance starter is kept at maximum resistance position.4. Now gradually reduce the resistance of the rotor resistance starter and note down the corresponding meter readings.

EE 1206 ELECTRICAL ENGINEERING LABORATORYGRAPH :

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RESULT :

Thus the speed of three phase slip ring induction motor was conducted and its performance characteristics were drawn.


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EE 1206 ELECTRICAL ENGINEERING LABORATORYEX.NO : 10 V CURVES AND INVERTED V CURVES OF SYNCHRONOUS MOTOR DATE :

AIM :To control the speed of three phase slip ring induction motor and draw its performance characteristics.

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SYNCHRONOUS MOTOR 1.2.3.4.





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EX: NO: 11 STUDY OF DC AND INDUCTION (AC) MOTOR STARTERSDATE :

AIM:To study the DC an Induction (AC) motor starters

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To study the DC an Induction (AC) motor starters.

Theory:

Induction motors take about 1.5 to 2 times its rated full load current at the time of starting. This heavy current although may not be dangerous for themotor. Therefore if normal supply is applied to the stationary motor, as in the case of a transformer, very large initial current is taken up by the primary, atleast for a short while. At the starting time there is no back emf to oppose the initial rush current.

The excessive current is objectionable. Because it will produce large line voltage drop that will affect the operation of the electrical equipmentconnected in the same line. Hence it is not advisable to start motors of rating about 25 KW to 40 KW.

Direct on-line starter:

In the circuit additionally thermal overload relays have been used to protect the motor winding against over heating. When the ON button is pressed,the conductor coil becomes energized and its gets closed. The motor gets connected to the supply mains. The motor continuously get the supply through the

contacts even when push button is released. The when the OFF button is pressed, the coil is de energized, the motor is disconnect from the supply. In case of an over load, the relay opens simultaneously the motor will stop.

Star Delta starters:

This types of starter is used in Squirrel cage Induction motor. The stator phase windings are first connected in star and ful l voltage is applied across theterminals. As the motor picks up speed, the windings are connected with Delta position by using change over switch. In star compared with Delta.Therebyconnecting the motor windings first in star then in Delta.

Rotor resistance starter:

This type of starter is used in slip ring Induction motor. In this type, for reducing the starting current during starting period, some extra resistance isincluded in rotor circuit. Then the external resistance provided in rotor circuit is increases gradually. The starting torque also increases proportionally. Whenthe motor attains the full speed the external resistance in Rotor circuit is fully cutout and the slip ring terminals are short circuited.


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AUTO TRANSFORMER STARTER:This starter consists of an auto transformer and a switch. When the switch is put on START position, a reduced voltage is applied across the motor

terminals. When the motor picks up the sapeed, say to 80% of its normal speed, the switch is put on RUN position. Then the auto transformer starter is cut of the current and full rated voltage gets applied across the motor terminals. The manual auto transformer starter can be made push button automatic controlledstarter so that the control switches over from start to run position as the motor picks up 80%of its speed

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starter so that the control switches over from start to run position as the motor picks up 80%of its speed.

THREE POINT STARTER:

the three terminals of the starting box are marked A,B and C. Only line is directly connected to one armature terminal and one field terminal which aretied together. the other line is connected to point A which is further connected to the starting arm L, through the over current release M.

To start the motor, the main switch is first closed and then the starting arm is slowly moved to the right. as soon as the arm makes contact with studno.1, the field circuit is directly connected across the line and at the same time full staring resistance RSis placed in series with the armature. The startingcurrent drawn by the armature V/(Ra+Rs). As the arm is further moved, the starting resistance is gradually cutoput till,


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