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SSC JE 2017: Electrical Machines Rankers Quiz 6
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Question 1
The secondary load impedance of a step-up transformer is The primary impedance will be
Question 2
A single phase transformer has a full-load secondary current of 500 A ; the primary current being one-fifth of this value. The transformer has the following parameters :
If the secondary is short-circuited, find the primary voltage required to circulate full-load current. Neglect no-load current.
If the secondary is short-circuited, find the primary voltage required to circulate full-load current. Neglect no-load current.
Question 3
In a transformer, the iron loss is and full-load Cu loss in The efficiency of the transformer at full-load at 0.8 p.f. lagging is
Question 4
If the slip of a 3-phase induction motor increases, the p.f. of the rotor circuit ………………………
Question 5
An 8-pole alternator runs at and supplies power to a 6-pole induction motor which has a full-load slip of 3%. The full-load speed of the motor is
Question 6
The starting torque of a 3-phase induction motor has maximum value. The rotor power factor is then
Question 7
Commutation conditions at full-load for a large D.C. machine can be checked by _________.
Question 8
The break test for the determination of efficiency of a D.C. machine is _______.
Question 9
How are transformers generally cooled for installations rated at less than 5 kVA?
Question 10
The losses in a transformer are:
(a) copper loss
(b) hysteresis loss
(c) eddy current loss
The constant power loss in a transformer is given by ;
(a) copper loss
(b) hysteresis loss
(c) eddy current loss
The constant power loss in a transformer is given by ;
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Jan 6ESE & GATE EE