A thermistor has_____________?
(A) positive temperature coefficient
(B) negative temperature coefficient
(C) zero temperature coefficient
(D) variable temperature coefficient
With three resistances connected in parallel, if each dissipates 20 W the total power supplied by the voltage source equals_____________?
(A) 10 W
(B) 20 W
(C) 40 W
(D) 60 W
The efficiency of a transformer will be maximum when_____________?
(A) copper losses = hysteresis losses
(B) hysteresis losses = eddy current losses
(C) eddy current losses = copper losses
(D) copper losses = iron losses
The permissible flux density in case of cold rolled grain oriented steel is around__________?
(A) 1.7 Wb/m2
(B) 2.7 Wb/m2
(C) 3.7 Wb/m2
(D) 4.7 Wb/m2
Sumpner’s test is conducted on transformers to determine_____________?
(A) temperature
(B) stray losses
(C) all-day efficiency
(D) none of the above
The dielectric strength of transformer oil is expected to be______________?
(A) lkV
(B) 33 kV
(C) 100 kV
(D) 330 kV
No-load on a transformer is carried out to determine______________?
(A) copper loss
(B) magnetising current
(C) magnetising current and loss
(D) efficiency of the transformer
The path of a magnetic flux in a transformer should have______________?
(A) high resistance
(B) high reluctance
(C) low resistance
(D) low reluctance
The no-load current drawn by transformer is usually what per cent of the full-load current ?
(A) 0.2 to 0.5 per cent
(B) 2 to 5 per cent
(C) 12 to 15 per cent
(D) 20 to 30 per cent
The degree of mechanical vibrations produced by the laminations of a transformer depends on____________?
(A) tightness of clamping
(B) gauge of laminations
(C) size of laminations
(D) all of the above