In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of_________________?
(A) less than 15 A
(B) more than 15 A
(C) 15 A
(D) none of the above
For the parallel operation of single phase transformers it is necessary that they should have___________?
(A) same efficiency
(B) same polarity
(C) same kVA rating
(D) same number of turns on the secondary sid
Minimum voltage regulation occurs when the power factor of the load is_____________?
(A) unity
(B) lagging
(C) leading
(D) zero
Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is_________________?
(A) approximately equal to one
(B) less than one
(C) great than one
(D) none of the above
Short circuit test on transformers is conducted to determine____________?
(A) hysteresis losses
(B) copper losses
(C) core losses
(D) eddy current losses
If a transformer is switched on to a voltage more than the rated voltage______________?
(A) its power factor will deteriorate
(B) its power factor will increase
(C) its power factor will remain unaffected
(D) its power factor will be zero
Open circuit test on transformers is conducted to determine____________?
(A) hysteresis losses
(B) copper losses
(C) core losses
(D) eddy current losses
Part of the transformer which is most subject to damage from overheating is_____________?
(A) iron core
(B) copper winding
(C) winding insulation
(D) frame or case
(D) transformer tank
For a transformer, operating at constant load current, maximum efficiency will occur at______________?
(A) 0.8 leading power factor
(B) 0.8 lagging power factor
(C) zero power factor
(D) unity power factor