Question

How short shunt and long shunt compound winding is selected?

(a) Mechanical considerations

(b) Switch reversal

(c) Performance

(d) Mechanical considerations and switch reversal

I have been asked this question at a job interview.

Question is from Methods of Excitation topic in chapter Commutation Process & Excitation Methods of DC Machines

Answer 1

Right choice is (d) Mechanical considerations and switch reversal

For explanation: In long shunt compound, the shunt field is connected across terminals. In short shunt compound, the shunt field is connected directly across the armature. There is no significant difference in machine performance for the two types of connections. The choice between them depends upon mechanical consideration or the reversing switches.