Test: Electrical Machines- 2 - Electrical Engineering (EE) MCQ
20 Questions MCQ Test GATE Electrical Engineering (EE) Mock Test Series 2025 - Test: Electrical Machines- 2
The starting current of a 3ϕ induction motor is 5 times the rated current, while the rated slip is 4%. The ratio of starting torque to full-load torque is
A single-phase transformer when supplied from 220V, 50 Hz has eddy current loss of 50W. If the transformer is connected to a voltage of 330V, 50 Hz, the eddy current loss will be
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If Pc and Psc represent core and full-load ohmic losses respectively, the maximum kVA delivered to load corresponding to maximum efficiency is equal to rated kVA multiplied by
A d.c. series motor is accidently connected to single-phase a.c. supply. The torque produced will be
The ‘synchronous-impedance method’ of finding the voltage regulation by a cylindrical rotor alternator is generally considered as
Generally the no-load losses of an electrical machine is represented in its equivalent circuit by a
A 6-pole, 3-phase alternator running at 1000 rpm supplies to a 8-pole, 3-phase induction motor which has a rotor current of frequency 2 Hz. The speed at which the motor operates is
For maximum current during ‘Slip Test’ on a synchronous machine, the armature mmf aligns along
A 3-phase 50 MVA 10kV generator has a reactance of 0.2 ohm per phase. Hence the per-unit value of the reactance on a base of 100 MVA 25 kV will be
The results of a ‘Slip-Test’ for determining direct-axis (Xd) and quadrature-axis (Xq) reactances of a star-connected, salient-pole alternator are given below:
Phase values: Vmax = 108V; Vmin = 96V, Imax = 12A, Imin = 10A. Hence the two reactances will be
A two-winding transformer is used as an auto-transformer. The kVA rating of the auto-transformer compared to the twowinding transformer will be
and type of auto-transformer
A 20 kVA, 2000/200V, 1-phase transformer has name-plate leakage impedance of 8%. Voltage required to be applied on the high-voltage side to circulate full-load current with the low-voltage winding short-circuited will be
The full-load copper-loss and iron loss of a transformer are 6400W and 5000W respectively. The copper-loss and ironloss at half load will be, respectively
In a 100 kVA, 1100/220V, 50 Hz single-phase transformer with 2000 turns on the high-voltage side, the open-circuit test result gives 200V, 91 A, 5kW on low-voltage side. The coreloss component of current is approximately
For a given torque, reducing the diverter-resistance of a d.c. series motor
reducing the diverter-resistance reduces the ϕ, so for a given load torque, Ia would increase. 
Possible three-to-three phase transformer connection for parallel operation is
A 4 kVA, 400/200V single-phase transformer has resistance of 0.02 p.u. and reactance of 0.06 p.u. Its actual resistance and reactance referred to high voltage side are respectively
Two 10 kV/440V, 1-phase transformers of ratings 600 kVA and 350 kVA are connected in parallel to share a load of 800 kVA. The reactances of the transformers, referred to the secondary side are 0.0198Ω and 0.0304Ω respectively (resistances negligible). The load shared by the two transformers will be respectively
The current drawn by a 120V d.c. motor with back e.m.f. of 110V and armature resistance of 0.4 ohm is
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25 docs|247 tests
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25 docs|247 tests
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