218 Electrical Power Systems Technology
Sample Problem:
Given: a transformer circuit has a power output of 2.5 kW and a
power input of 2,550 W.
Find: the efficiency of the transformer.
Solution:
2,500 W
% Eff = ———— × 100
2,550 W
% Eff = 98%
The losses that reduce efficiency, in addition to flux leakage, are cop-
per and iron losses. Copper loss is the I^2 R loss of the windings, while iron
losses are those caused by the metallic core material. The insulated lami-
nations of the iron core help to reduce iron losses.
Figure 8-9. Types of iron-core transformers: (A) Closed-core type, (B) Shellcore
type