Related Questions

In an actual transformer the iron loss remains practically constant from noload to fullload because
A value of transformation ratio remains constant
B permeability of transformer core remains constant
C core flux remains practically constant
D primary voltage remains constant
In a synchronous motor it the back e.m.f. generated in the armature at noload is approximately equal to the applied voltage, then
A the motor is said to be fully loaded
B the torque generated is maximum
C the excitation is said to be zero per cent
D the excitation is said to be hundred per cent
An over excited synchronous motor on noload is known as
A synchronous condenser
B generator
C induction motor
D alternator
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 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
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
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
In a step down transformer, there is a charge of 15A in the load current. This results in changing of supply current of
A Less than 15 A
B Greater than 21 A
C More Than 21A
D None
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

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