Page 172 - CITS - Electrician - Trade Practical

ELECTRICIAN - CITS

For star connection
Resistance per phase Rp = V/I x ½
Rp = R/2
For delta connections
Resistance between two terminals R = V/I

Measured resistance = 2/3 Rp
Rp = 3/2 R

Tabel 1
DC supply voltage Ammeter reading Resistance of stator
(one phase)

TASK 2: To carry and no-load test on 3Ф squirrel cage induction motor

1 Connect the motor for no load test as per diagram Fig 2
2 Check the supply for rated value and switch ON the ICTP.
3 Adjust the autotransformer to set the voltage to the rated value
4 Start the motor without any load.
5 Read and record the meter readings in Table 2.

6 Switch OFF the motor.
7 Keep the auto transformer at zero output voltage position
8 Switch OFF the supply and disconnect the circuit.
9 Calculate the constant losses of the motor
Table 2

Total No load
Line current Constant
Sl.No Line Voltage Wattmeter 1 Wattmeter 1 input power
I losses
W0
1
2
3

Fig 2

155

CITS : Power - Electrician & Wireman - Exercise 71