Question

What are the indications and causes of an overloaded generator?

Answer.

A generator is said to be overloaded if a greater output is taken from it than it can safely carry.

Overloading is indicated by

(i) Excessive sparking at brushes and

(ii) Overheating of the armature and other parts of the generator.

Most likely causes of overloading are :

(a) Excessive voltage—as indicated by the voltmeter or the increased brilliancy of the pilot lamp.

This could be due to over-excitation of field magnets or too high speed of the engine.

(b) Excessive current—which could be due to bad feeding of the load.

(c) Reversal of polarity—this happens occasionally when the series or compound-wound generators are running in parallel.

Polarity reversal occurs during stopping by the current from the machines at work.

(d) Short-circuit or ground in the generator itself or in the external circuit.