Formula used:

Circuit Diagrams:,

Calculations:

By formulae, torque = Wm/wm(rad/s)

= Wm*60 / 2*𝜋*speed(rpm)

Efficiency = Wm*100 / Input Power(W)

We have the following table

S.No Load Speed W (in W) VG IG Wm Torque efficiency

(watts) (rpm) (Volts) (Amp) (W) (N-m) (%)

1 0 1450 110 202 0 60 0.395 54.54

2 15 1432 118 192 0.03 65.84 0.44 55.80

3 25 1424 124 186 0.11 82.71 0.55 66.70

4 40 1408 132 180 0.17 95.97 0.65 72.70

5 55 1392 142 174 0.22 107.28 0.74 75.55

6 65 1376 150 168 0.26 116.25 0.81 77.5

7 80 1348 164 160 0.303 126.1 0.89 76.89

Result:

1. At no load torque = 0.395 N-m

Efficiency = 54.54%

2. From graph efficiency max = 74.8%

Inference:

1. Plot of efficiency Vs torque indicated that in beginning, efficiency first increases with increase in

torque and reaches the maximum value and after that starts decreasing.

2. Plot of speed Vs torque indicates that speed goes on decreasing with increase in load torque.

Precautions:

1. Before switching on the circuit get it checked by the instructor.

2. Readings for different loads should be taken at constant input voltage.

3. Measurements of voltage, current and speed must be done carefully.

4. Graph must be plotted with proper scale.

5. For wattmeter readings, multiplication factor must be taken into account.