1
GATE EE 2002
MCQ (Single Correct Answer)
+2
-0.6
A 400V/200V/200V, 50 Hz three winding transformer is connected as shown in Figure. The reading of the voltmeter 'V' will be GATE EE 2002 Electrical Machines - Transformers Question 49 English
A
0 V
B
400 V
C
600 V
D
800 V
2
GATE EE 2002
MCQ (Single Correct Answer)
+1
-0.3
If a 400 V, 50 Hz, star connected, 3 phase squirrel cage induction motor is operated from a 400 V, 75 Hz supply, the torque that the motor can now provide while drawing rated current from the supply?
A
reduces
B
increases
C
remains the same
D
increase or reduces depending upon the rotor resistance
3
GATE EE 2002
MCQ (Single Correct Answer)
+2
-0.6
The flux per pole in a synchronous motor with the field circuit ON and the stator disconnected from the supply is found to be $$25$$ $$mWb.$$ When the stator is connected to the rated supply with the field excitation unchanged, the flux per pole in the achine is found to be $$20$$ $$mWb$$ while the motor is running on no load. Assuming no load losses to be zero, the no load current down by the motor from the supply
A
lags the supply voltage
B
leads the supply voltage
C
is in phase with the supply voltage
D
is zero
4
GATE EE 2002
Subjective
+5
-0
A $$415$$ $$V,$$ $$2$$ pole, $$3$$ phase, $$50$$ $$Hz,$$ star connected, non-salient pole synchronous motor has synchronous reactance of $$2\,\Omega $$ per phase and negligible stator resistance. At a particular field excitation, it draws 20 A at unity power factor from a $$415$$ $$V,$$ $$3$$ phase, $$50$$ $$Hz$$ supply. The mechanical load on the motor is now increased till the stator current is equal to $$50$$ $$A.$$ The field excitation remains unchanged. Determine:
$$(a)$$ the per phase open circuit voltage $${E_0}$$
$$(b)$$ the developed power for the new operating condition and corresponding power factor.
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