Page 646 - Basic Electrical Engineering

Iron, friction and windage, and field copper = No-load input − I ao 2 R a
losses

2
= 1760 − 6 × 0.1
= 1760 − 3.6

= 1756.4 W

These are constant losses.
Note that I ao 2 R loss in the armature at no load is very small.
a
The generator is rated at 50 kW and 220 V.

The generator output current at full load.

2
Full-load armature Copper loss = I R a
a
= (229.2) × 0.1
2
= 5253 W

This is the variable loss.

Figure 7.27

Efficiency of the generator in percentage = Output/(Output + Constant losses
+ Variable loss)