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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:
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 and note 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 rated current 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 circuit diagram.
4. By adding the load through the loading rheostat note down the ammeter, voltmeter readings for various values of load.
FORMULA USED:
OC TEST:
1. No load power factor (CosΦo)=P0/V0I0
V0 – No load voltage per phase in volts
I0 – No load current per phase in amps
P0=W1+W2 - No load current per phase in watts
2. Working component current (Iw) = I0(ph) x CosΦ0
3. Magnetizing current (Im) = I0(ph) x SinΦ0
4. No load resistance (R0) = V0/I0(ph) Cos Φ0 in Ω
5. No load resistance (X0) = V0/I0(ph) Sin Φ0 in Ω