Page 200 - CITS - Electrician - Trade Practical

ELECTRICIAN - CITS

TASK 2: Start the motor as induction motor
1 Adjust the field rheostat of DC supply to rated current, and keep the potential divider at zero output position and
without engagement of mechanical load.
2 Keep the DC field winding shorted, by pressing button S2.
3 Keep S2 depressed, switch on the 3-ph. supply, start the synchronous motor and let motor reach 95% of rated
speed

TASK 3: Run the motor as synchronous motor

1 Release switch s2 to excite the field winding by DC supply. (motor pulls into synchronism now)
2 Measure the speed by tachometer
3 Measure speed, supply voltage, frequency, line current, and field excitation current and record
4 Calculate the synchronous speed of the motor by using the formula.NS =120 f/P

5 Compare the synchronous speed with the measured speed, and ensure measured speed is equal to synchronous
speed.

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CITS : Power - Electrician & Wireman - Exercise 82