em2 manual for 2009 batch

8/4/2019 Em2 Manual for 2009 Batch

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RVS COLLEGE OF ENGINEERING &TECHNOLOGY

(Approved by AICTE and Affiliated to Anna University- Coimbatore)

KumaranKottam., Sulur, COIMBATORE - 641402.

DEPARTMENT OF

ELECTRICAL AND ELECTRONICS ENGINEERING

LAB MANUAL

FOR

Electrical MachinesII Laboratory

BE - VSemester

PREPARED BY

T.SENTHIL KUMAR


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ELECTRICAL MACHINESII LABORATORY (REGULATION 2008) 0 0 3 100

LIST OF EXPERIMENTS:

1. Regulation of three-phase alternator by EMF, MMF and ZPF methods.

2. Load test on three-phase alternator.

3. Regulation of three-phase salient pole alternator by slip test.

4. V and Inverted V curves of Three Phase Synchronous Motor.

5. Load test on three-phase squirrel cage induction motor.

6. Load test on three-phase slip ring induction motor.

7. No load and blocked rotor test on three-phase induction motor.

8. Separation of No-load losses of three-phase induction motor.

9. Loss summation method on three-phase induction motor.

10. Load test on single-phase induction motor

11. Determination of Equivalent circuit of single-phase induction motor

12. Speed control of three phase induction motor by V/f method

P = 45 Total = 45


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REGULATION OF THREE PHASE ALTERNATOR BY EMF, MMF, and ZPF

AIM

To conduct OC, SC and ZPF test on the three phase alternator and to predetermine the

regulation of 3 phase alternator by EMF method, MMF method, & ZPF method also to verify by

vector diagram.

APPARATUS REQUIRED

S.no Name of the Apparatus Range Type Quantity

PRECAUTION

1. The motor field rheostat should be kept in the minimum resistance position.2. The alternator field potential divider should be in the minimum voltage position.3. Initially all switches are in open position.PROCEDURE

A. OC.Test

1. Note down the name plate details of motor and alternator2. Connections are given as per circuit diagram.3. The DPST is closed on supply side.


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4. Using three point starter, the motor is started. The alternator is brought to Rated speed byvarying motor field rheostat.

5. By varying the alternator field potential divider in steps, for various values of field current,the voltmeter readings across the alternator are noted by keeping the TPST switch under

normal condition.

6. The OCC curve (Eph Vs If ) is drawn from the above rating.B. SC Test

1. By ensuring the zero voltage across the alternator TPST switch is closed to position 1.2. SC test is conducted with alternator armature rated current which has been set by adjusting

alternator field potential divider and corresponding field current is noted.

3. The SC curve (Isc Vs If) is drawn from the above rating.C. ZPF Test

1. Connections are made as per the circuit diagram.

2. Give the supply by closing the DPST switch.

3. Using the Three Point Starter start the motor to run at the synchronous speed by varying the

motor field rheostat.

4. By varying the alternator field potential divider in steps, for various values of field current,the Voltmeter readings across the alternator are noted by keeping the TPST switch under normal

condition.

5. Conduct a Short Circuit Test by closing the TPST switch to position 1 and adjust the potential

divider to circulate the rated Armature Current and tabulate the corresponding field current.

6. To conduct a ZPF test change the TPST switch to position 2.

7. Adjust the alternator field potential divider for Full Load current passing through either

Inductive load with zero power factor and tabulate the readings.

D. Measurement of Ra

1. Connections are given as per circuit diagram.2. The DPST is closed on supply side.


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4. Draw the perpendicular line CD with the line AC (Ira drop) to represent IXs drop.

5. Join the points D and A to represent the IZs drop.

6. Join the points O and D and measure the length OD by voltage scale to find Open Circuit

Voltage Eo.

7. Find the percentage regulation by using suitable formula.

PROCEDURES 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 Current)

3. Draw the line OL to represent If which gives the rated generated voltage (V).

4. Draw the line LA at an angle (90 + ) to represent If which gives the rated full load

current (Isc) on short circuit (90+) for lagging power factor and (90 - ) for leading

power factor].

5. Join the points O and A and find the field current(I f) by measuring the distance OA that

gives the Open Circuit Voltage (Eo)from the Open Circuit Characteristics.

6. Find the percentage regulation by using suitable formula.

PROCEDURE TO DRAW THE VECTOR DIAGRAM FOR MMF METHOD:

1. Draw the line OA that represents the rated voltage V.

2. Draw line OB to represent the rated current Ia, which makes an angle (It may lags/leads/in

phase) with the voltage.

3. Draw the line AC to represent IRa drop, which is parallel to Current Axis (OB)

4. Draw the perpendicular line CD with the line AC (Ira drop) to represent IXs drop.

5. Join the points D and A to represent the IZs drop.

6. Join the points O and D and measure the length OD by voltage scale to find Open Circuit

Voltage Eo.7. Find the percentage regulation by using suitable formula.

PROCEDURE TO DRAW THE POTIER DIAGRAM (ZPF)

1.Draw the Open Circuit Characteristics curve.(Generated Voltage per phase Vs Field Current)


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2.Mark the point A at X-axis, which is obtained from Short Circuit with full load armaturecurrent.

3.From the ZPF test mark the point B for the field current to the corresponding rated armaturecurrent and rated voltage.

4.Draw the ZPF curve which passing through the point A and B in such a way parallel to theOpen Circuit characteristics curve.

5.Draw the tangent for the OCC from the origin air gap line.6.Drew the line BC from B towards Y-axis, which is parallel and equal to OA.7.Draw the parallel line for the tangent from C to OCC curve.8.Join the point B and D also represent armature leakage reactance (Ix L) drop BE representarmature reaction excitation (Ifa).

PROCEDURE TO DRAW THE VECTOR DIAGRAM (ZPF)

1. Select the suitable voltage and current scale.

2. For the corresponding power angle draw the voltage vector OA and current vector OB.

3. Draw the vector AC with the magnitude Ira drop, which should be parallel to the vector OB.

4. Draw the perpendicular CD to AC from the point c with the magnitude of IxL drop.

5. Join the points O&D, which will be equal to the air gap voltage.

6. Find out the Field Current (Ife) for the corresponding air gap volt (Eair) from OCC curve.7. Draw the vector OF with the magnitude of Isc, which should be perpendicular to the vector

FG from F with the magnitude of A in such a way it is parallel to current vector OB.

8. Join the points O&G, which will be equal to field excitation current (If).

9. Draw the perpendicular line to vector OG from the point O and extend vector CD is such a

point intercept the perpendicular to line at point H.

10. Find out the open circuit voltage (Eo) for the corresponding field excitation (If) from the

OCC curve.

11. Find out the regulation from the suitable formula.


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RESULT:

Thus the regulation of three phase alternator by EMF, MMF, and ZPF method. Also to

verify by vector diagram.


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LOAD TEST ON THREE PHASE ALTERNATOR

AIM

To conduct the load test on single phase alternator.

APPARATUS REQUIRED

S.no Name of the apparatus Range Type Quantity

PRECAUTION

1. The motor field rheostat should be kept in the minimum resistance position.2. The alternator field potential divider should be in the minimum voltage position.3. Initially all switches are in open position.PROCEDURE

1. Note down the name plate details of motor and alternator2. Connections are given as per circuit diagram.3. The DPST is closed on supply side.4. Using three point starter, the motor is started. The alternator is brought to Rated speed by

varying motor field rheostat.

5. By varying the alternator field potential divider in steps up to the rated alternator terminalvoltage.

6. Close the DPST switch on alternator terminal side, then by step and apply load up to therated current.


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7. Note down corresponding reading of voltmeter, ammeter and field current noted and plot thegraph.

MODEL CALCULATION

RESULT

Thus the load test on 3 phase alternator is successfully completed and the graph is

plotted.


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REGULATION OF THREE-PHASE SALIENT POLE ALTERNATOR BY SLIP TEST

AIM

To conduct the slip test on three phase alternator and predetermination the regulation through

vector diagrams

APPARATUS REQUIRED

S.NO Name of the Apparatus Range Type Quantity

PRECAUTION

1. The Motor field Rheostat should be kept in minimum resistance position.2. The Alternator field should be kept open throughout the experiment.3. The direction of rotation due to prime mover and due to the Alternator run as the motor

should be same.

4. Initially all the switches are kept openPROCEDURE

1. The name plate details of the motor and alternator are noted.2. Connections are made as per the circuit diagram.3. Give the supply by closing the DPST Switch4. Using the three point starter, start the motor to run at the synchronous speed by varying the

motor field rheostat at the same time check whether the alternatorfield has been opened or


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not Apply 20% to 30% of the rated voltage to the armature of the alternator by adjusting the

autotransformer.

5. To obtain the slip and the maximum oscillations of pointers, the speed is reduced slightlylesser than the synchronous speed.

6. Maximum current , minimum current , maximum voltage and minimum voltage are noted.The direct and quadrature axis resistances and reactances are calculated.

PROCEDURE TO DRAW THE VECTOR DIAGRAM:

1. Draw the line OA vector that represents the rated voltage v.2. Draw the line OB vector to represents the rated current I, which makes an angle (it may

lag/lead/in phase) with the voltage.

3. Draw the line AC vector to represent IRa drop which is parallel to OB vector.4. Draw the perpendicular line CD vector to the line AC ( IRa drop )that represent IXq drop.5. Draw the line from the origin through the point D, which consist the no load voltage (E o).6. Draw the pole axis through origin, which should be perpendicular to vector OD.7. Draw the perpendicular line tom the pole axis from the same (point E) which should be

passed through the point B[where, Vector OE represents direct access current (Id ) and

vector EB represent quadrature axis current (Iq)].

8.

Find out the reactive voltage dropsX

dI

d& I

qX

q.

9. Draw a parallel line (ie perpendicular to Id) to OD vector from the point C with themagnitude of the drop IdXd (line CF).

10.Draw parallel line i.e. perpendicular to Iq to OE vector from F with the magnitude dropIq,Xq(line FG).

11.Let the point at where the Iq,Xq drop meets OD line be G here the vector OG is representthe no load voltage(EO).

12.Find out voltage regulation by using the suitable formula.


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MODEL CALCULATION

RESULT

Thus the slip test on three phase alternator was conducted and its regulation was

predetermined.


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LOAD TEST ON THREE PHASE INDUCTION MOTOR (SLIP RING)

AIM

To conduct load test on three-phase Slip Ring induction motor.

APPARATUS REQUIRED

S.No Name Of Apparatus Type Range Quantity

PRECAUTION

The motor should be started without any load.

PROCEDURE

1. Connections are given as per the circuit diagram.2. The TPSTS is closed and the motor is started using online starter to run at rated speed.3. At no load the speed, current, voltage and power are noted down.4. By applying the load gradually with the help of spring balance and brake drum

arrangements.

5. The speed, current, voltage, power and spring balance reading are noted for variousvalues.

6. The motor is switched off after bringing the load to the initial position.


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FORMULAE USED

Torque = (s1-s2) r x 9.81 Nm

s1, s2 - spring balance reading in kg

r - Radius of brake drum in m

Output power =60

NT2watts

N - Rotor speed in rpm

T - Torque in Nm

Input power = (w1+w2) watts

w1,w2 - wattmeter reading in watts

Percentage of efficiency = (Output/Input) x 100

Percentage of slip = (NS-N) NS x 100

NS - synchronous speed in rpm

N - Speed of motor in rpm

Power factor = watts

CALCULATION:


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RESULT:

Thus the load test on three phase slip ring induction motor was performed and electrical

and mechanical characteristics have been drawn.


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NO LOAD AND BLOCKED ROTOR TEST ON THREE PHASE

SQUIRREL CAGE INDUCTION MOTOR

AIM:

To conduct the No Load test and Blocked rotor test on three phase squirrel cage

induction motor and to draw the equivalent circuit.

FUSE RATING:

No load: 10% of rated current (Full load current)

Load: 125%of rated current (Full load current)

APPARATUS REQUIRED:

S.No Name of the Apparatus Range Type Quantity


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PRECAUTIONS:

The autotransformer should be kept at minimum voltage position.

PROCEDURE:

Note down the name plate details of motor.

1. For no-load open circuit test by adjusting autotransformer, apply rated voltage andnote down the ammeter and wattmeter readings. In this test rotor is free to rotate.

2. For short circuit (or) blocked rotor test by adjusting autotransformer apply ratedcurrent and note down the voltmeter and wattmeter readings. In this test rotor is

blocked (not to rotate)

3. After that make the connection to measure the stator resistance as per the circuitdiagram.

4. By adding the load through the loading rheostat note down the ammeter, voltmeterreadings for various values of load.

FORMULA USED:

OC TEST:

1. No load power factor (Coso)=P0/V0I0V0No load voltage per phase in volts

I0No load current per phase in amps

P0=W1+W2 - No load current per phase in watts

2. Working component current (Iw) = I0(ph) x Cos03. Magnetizing current (Im) = I0(ph) x Sin04. No load resistance (R0) = V0/I0(ph) Cos 0in 5. No load resistance (X0) = V0/I0(ph) Sin 0in

SC TEST:

1. Motor equivalent Impendence referred to stator (Zsc(ph))=Vsc(ph)/Isc(ph) in 2. Motor equivalent Resistance referred to stator (Rsc(ph)) =Psc(ph)/I2sc(ph) in 3. Motor equivalent Resistance referred to stator(Xsc(ph))=(Zsc(ph)

2-Rsc(ph)

2^(1/2) in


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4. Rotor Resistance referred to stator(R21(ph)) = Rsc(ph)R1 in 5. Rotor Resistance reffered to stator (X2

1(ph)) =Xsc(ph) /2 = X1 in

Where R1- stator resistance per phase

X1stator resistance per chapter

R1 = R(ac)=1.2 x R(dc)

6. Equivalent load resistance (RL) = R2 (1/s -1) in

NSpeed of the motor in rpm

CALCULATION:


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RESULT:

This is the No Load test and Blocked rotor test on three phase squirrel cage induction

motor and to draw the equivalent circuit.


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LOAD TEST ON SINGLE PHASE INDUCTION MOTOR

AIM:

To determine the performance characteristics of the given single phase induction motor

by direct loading.

APPARATUS REQUIRED:

S.no Name of the apparatus Type Range Quantity

Precaution


Procedure

1. Note down the name plate details of motor. Connections are given as per the circuit diagram.2. The DPST is closed in the supply side.3. The motor is started by gradually varying the autotransformer and the rated voltage is

applied.

4. At no load, the speed, current, voltage and power are noted down.5. The load is gradually applied with the help of spring balance and brake drum arrangement.6. The speed, current, voltage, power and spring balance reading are noted for various loads up

to the rated current.

7. The motor is switched off after releasing the load.

FORMULA USED:


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1. Radius of brake drum (r) = (Circumference/2) in meters2. Torque (T) = (S1~S2) x 9.81x r in Nm

3. Power output (Po) = 2NT / 60 in Watts4. Power input (Pi) = VL x IL Cos Watts (Power input is given by the wattmeter reading)5. %Efficiency () = Po / Pi x 100 in %6. BHP = Po/ 735.5

CALCULATION:


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RESULT:

Thus the performance characteristics of the given single phase induction motor by

direct loading is determined.


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Load Test on Three Phase Induction Motor

(Squirrel gauge)

Aim

To conduct load test on three-phase squirrel cage induction motor.

Apparatus Required

S.No Name Of Apparatus Type Range Quantity

Precaution


Procedure

1) Connections are given as per the circuit diagram.2) The TPSTS is closed and the motor is started using star-delta starter to run at rated speed.3) At no load the speed, current, voltage and power are noted down.4) By applying the load gradually with the help of spring balance and brake drum arrangements.5) The speed, current, voltage, power and spring balance reading are noted for various values.6) The motor is switched off after bringing the load to the initial position.

Formulae Used

Torque = (s1-s2) r x 9.81 Nm

s1, s2 - spring balance reading in kg

r - Radius of brake drum in m


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Output power =60

NT2watts

N - Rotor speed in rpm

T - Torque in Nm

Input power = (W1+ W2) watts

W1,W2 - Wattmeter reading in watts

CALCULATION:

Result:

Thus the load test on three phase squirrel cage induction motor was performed

and electrical and mechanical characteristics have been drawn

em2 manual for 2009 batch

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