Circuits used in Lab:

Calculation:

1) Open Circuit Test :

RM1 = Voc2/ Woc

= (230)2/10 = 5290 ohm

XM1 = Voc / √[Ioc2 – (Woc / Voc)]

= 230/[0.182 – (10/230)2]1/2 = 1316.77 ohm

2) Short Circuit Test :

R1eq = Wsc / Isc2

= 32 / 22 = 8 ohm

X1eq = √[(Vsc / Isc) 2 – R1eq

2]

= 7.5 ohm

Efficiency = 500*Pf / [ 500*Pf + (500/230)2R1eq + Woc ]

%Regulation = [ (I1R1eqCosθ + I1X1eqSinθ) / V1rated ] *100

Serial No. Cos θ Efficiency %Regulation

1 0.8 88.9% 10.3%

2 0.6 85.5% 10.2%

# Calculation For The Load Test:

Serial No. Load ( W) Secondary Voltage (V2)

Secondary Current (I2)

Secondary Wattmeter Reading ( W2)

Primary Current ( I1)

Primary Wattmeter Reading (W1)

1 No Load 120 0 0 0.25 16

2 40 120 0.1 20 0.28 32

3 100 120 0.3 45 0.34 54

4 140 120 0.44 60 0.39 72

5 200 120 0.58 80 0.44 88

6 240 120 0.71 100 0.5 102

7 300 120 0.87 120 0.58 124

8 340 120 1.02 135 0.65 140

9 400 120 1.14 160 0.71 156

10 440 120 1.27 165 0.78 172

11 500 120 1.44 200 0.86 196

12 540 120 1.56 210 0.92 212

Serial No.

Load (W)

Cos θ Sin θ Efficiency %Regulation

No load 0 0 0 0

1 40 0.9028 0.4300 0.7541 11.28

2 100 0.9124 0.3886 0.7432 10.97

3 140 0.9232 0.3843 0.7042 10.41

4 200 0.9352 0.3541 0.7247 10.67

5 240 0.9412 0.3378 0.7168 10.45

6 300 0.9845 0.1701 0.7234 10.48

7 340 0.9641 0.2655 0.7478 10.64

8 400 0.9764 0.2159 0.7198 10.68

9 440 0.9865 0.1638 0.7624 10.29

10 500 0.9654 0.2608 0.7241 10.94

11 540 0.9741 0.2261 0.7341 10.14

0

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10

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16

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

%Regulation(y axis) Vs Load current(x axis)

%Regulation

Linear (%Regulation)

Conclusion/Result:

1. Plot of Efficiency Vs Load current comes out to be a straight line which is

parallel to X axis..

2. Plot of % regulation Vs Load current comes out to be a straight line.

Precautions:

1. All connections should be tight.

2. The test should be performed at rated frequency.

3. Before switching on the supply, get your circuit checked by instructor.

4. Test should be performed carefully and readings should be taken attentively.

5. Shoes must be put on while doing experiment.

0

0.2

0.4

0.6

0.8

1

1.2

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

Efficiency(y axis) Vs Load current(x axis)

Efficiency

Linear (Efficiency)