Primary winding of a transformer
could either be a low voltage or high voltage winding
is always a low voltage winding
is always a high voltage winding
none of the above
could either be a low voltage or high voltage winding
Efficiency of a power transformer is of the order of
25 per cent
50 per cent
100 per cent
98 per cent
98 per cent
A common method of cooling a power transformer is
natural air cooling
air blast cooling
oil cooling
any of the above
oil cooling
The no load current in a transformer lags behind the applied voltage by an angle of about
75°
90°
120″
180°
75°
In a given transformer for given applied voltage losses which remain constant irrespective of load changes are
hysteresis and eddy current losses
copper losses
friction and windage losses
none of the above
hysteresis and eddy current losses
If the percentage impedances of the two transformers working in parallel are different then
parallel operation will be not possible
parallel operation will still be possible but the power factors at which the two transformers operate will be different from the power factor of the common load
transformers will be overheated
power factors of both the transformers will be same
parallel operation will still be possible but the power factors at which the two transformers operate will be different from the power factor of the common load
If R2 is the resistance of secondary winding of the transformer and K is the transformation ratio then the equivalent secondary resistance referred to primary will be
R2IK2
4
2
1
R2IK2
In a transformer the tappings are generally provided on
high voltage side
secondary side
primary side
low voltage side
low voltage side
The transformer ratings are usually expressed in terms of
volts
amperes
kVA
kW
kVA
Transformer breaths in when
load on it decreases
none of the above
load remains constant
load on it increases
load on it decreases
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