Search
.Management Sciences
Category: Transformers
The use of higher flux density in the transformer design____________?
A. reduces weight per kVA
B. reduces iron losses
C. reduces copper losses
D. increases part load efficiency
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
Natural oil cooling is used for transformers up to a rating of____________?
A. 3000 kVA
B. 1000 kVA
C. 500 kVA
D. 250 kVA
The efficiency of a transformer, under heavy loads, is comparatively low because_______________?
A. copper loss becomes high in proportion to the output
B. iron loss is increased considerably
C. voltage drop both in primary and secondary becomes large
D. secondary output is much less as compared to primary input
Losses which occur in rotating electric machines and do not occur in transformers are___________?
A. friction and windage losses
B. magnetic losses
C. hysteresis and eddy current losses
D. copper losses
The maximum load that a power transformer can carry is limited by its________________?
A. temperature rise
B. dielectric strength of oil
C. voltage ratio
D. copper loss
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
Which type of winding is used in 3 phase shell-type transformer?
A. Circular type
B. Sandwich type
C. Cylindrical type
D. Rectangular type
Recent Comments