Question

A shunt-wound generator has a magnetisation-curve given by the figures below. The total resistance in the field circuit is 20Ω and the armature resistance is 0.02Ω. With the machine on load, estimate the e.m.f. generated and the armature current when the terminal voltage of the machine is 140V.

Field current (A)—amperes

1.2 2.8 5.0 7.0 7.7 9.0 11.0

Generated e.m.f. (E)—volts

46 88 126 149 154 162 168