Transformer Operation (Single-Phase Transformers)

Question 1

Name two types of losses that contribute to core losses

Answer 1

Hysteresis

Eddy Currents

Question 2

Transformer core losses remain basically constant from no-load to full-load conditions

a) True
b) False

Answer 2

a) True

Question 3

If a constant voltage is applied to a transformer, it’s core losses are ________ from no-load to full-load conditions.

Answer 3

Constant

Question 4

Secondary copper losses are equal to to the square of the secondary (current/voltage) times the resistance of the secondary winding.

Answer 4

Secondary copper losses are equal to to the square of the secondary CURRENT times the resistance of the secondary winding.

Question 5

The copper losses of a transformer can be determined by a

a) short circuit test
b) open circuit test

Answer 5

a) Short circuit test

Question 6

In a short circuit test the rated secondary current is obtained at a primary voltage that is considerably (less/more) than the rated primary voltage.

Answer 6

In a short circuit test the rated secondary current is obtained at a primary voltage that is considerably LESS than the rated primary voltage.

Question 7

What factors affect transformer efficiency

Answer 7

Load capacity
Power factor
Losses

Question 8

Percent impedence voltage is generally between ___ and ___ %

Answer 8

2 and 10 %