Related Questions

A single phase transformer has a maximum efficiency of 90% at full load and unity power factor. Efficiency at half load at the same power factor is -
A 87.8%
B 86.7%
C 88.26%
D 88.9%
The output transformer used in a power amplifier is a ___________ transformer
A 1:1 ratio
B Step-up
C Step-down
D None of the above
Power amplifiers generally use transformer coupling because transformer per-mits
A Cooling of the circuit
B Impedance matching
C Distortionless output
D Good frequency response
The maximum efficiency of transformer coupled class A power amplifier is ___________
A 30%
B 50%
C 80%
D 45%
Which of the following is the main advantage of an auto-transformer over a two-winding transformer?
A Eddy losses are totally eliminated
B Copper losses are negligible
C Saving in winding material
D Hysteresis losses are reduced
The changes in volume of transformer cooling oil due to variation of atmospheric tem-perature during day and night is taken care of by which part of transformer
A Conservator
B Breather
C Bushings
D Buchholz relay
Which of the following is the main advantage of an auto-transformer over a two winding transformer?
A Hysteresis losses are reduced
B Saving in winding material
C Copper losses are negligible
D Eddy losses are totally eliminated
An ideal transformer will have maximum efficiency at a load such that
A copper loss = iron loss
B copper loss
C copper loss > iron loss
D none of the above
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
In a transformer routine efficiency depends upon
A supply frequency
B load current
C power factor of load
D both (B) and (C)

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