Q.1
##### When will be the efficiency of a transformer maximum?
• a) Copper losses = hysteresis losses
• b) Hysteresis losses = eddy current losses
• c) Eddy current losses = copper losses
• d) Copper losses = iron losses
Q.2
##### Efficiency of a power transformer is near to the ___________
• a) 100 per cent
• b) 98 per cent
• c) 50 per cent
• d) 25 per cent
Q.3
##### On which factors transformer routine efficiency depends upon?
• a) Supply frequency
• c) Power factor of load
Q.4
Q.5
##### At which load condition maximum efficiency of a distribution transformer will be achieved?
• b) At 60% full load
• c) At 80% full load
Q.6
Q.7
##### For a transformer given, 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
Q.8
##### Why efficiency of a transformer, under heavy loads, is comparatively low?
• 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
Q.9
##### The efficiencies of transformers compared to electric motors of the same power are ___________
• b) Much smaller
• c) Much higher
• d) Can’t comment
Q.10
• a) 4/3
• b) 3/4
• c) 9/16
• d) 16/9
Q.11
##### What is the correct formula of efficiency of a device?
• a) Input /output
• b) Output/losses
• c) 1- (losses/ (output + losses))
• d) Cannot be determined
Q.12
##### AkVA transformer is having efficiency ofat full load and also atof full load; both at unity power factor. Then Pi is ___________
• a) 16.45 kW
• b) 9.87 kW
• c) 14.57 kW
• d) Can’t be calculated
Q.13
##### AkVA transformer is having efficiency ofat full load and also atof full load; both at unity power factor. Then Pc is ___________
• a) 16.45 kW
• b) 9.87 kW
• c) 14.57 kW
• d) Can’t be calculated
Q.14
• a) 86.44%
• b) 96.44%
• c) 97.44%
• d) 99.12%