If full-load Cu loss of a transformer is 1600 W, its Cu loss at half full load would be
400 W
800 W
1600 W
6400 W
Which of the following gives the highest secondary voltage for a given primary voltage?
Y - f:.. Connection
f:.. - Y connection
Y - y connection
f:.. - f:.. Connection.
Increase in the secondary current of a transformer brings about increase in primary current. This is. possible because
Secondary and primary windings are inductively coupled
Secondary and primary windings are capacitive coupled
Secondary and primary windings are conductively connected.
For given applied voltage in a transformer, if its magnetic core is replaced by a non-magnetic core
It will draw more magnetizing current and magnetic flux' will increase
It will draw more magnetizing current but magnetic flux will remain same
IT will not draw more magnetizing current and magnetic flux will decrease
There will be no change either in magnetizing current or in magnetic flux.
If an ammeter in the secondary of a 100/1 0 V transformers reads 10 A, what would be the current in the primary?
1a
2a
10a
100a
Why deposition of dust should never be allowed to accumulate on the windings and core of a dry-type transformer?
As it absorbs oil and grease
Because it may short-circuit the windings
Because it tends to corrode metal surface
Because it reduces dissipation of heat.
Primary leakage flux “is that flux which
Links with primary but not with secondary winding
Links with both primary and secondary windings
Does not link with any of primary and secondary findings
Does not link with primary but links with secondary winding.
The full-load efficiency of a transformer can be determined provided its losses are known. These losses
Can be found by performing short-circuit and open circuit tests
Can be found by measuring the input to the primary with secondary open
Can be found by calculating the I2R losses
Cannot be obtained except by actually loading the transformer fully.
The relative polarity of the windings of a transformer may be determined by
Polarity test
Back-to-back test
Short-circuit test
Open-circuit test.
The full load rating of a transformer is 90 kW at a power factor of 0.9. Its kV A rating would be
70 kV A
86.6 kV A
100 kV A
150 kV A.