Question

If the residual magnetism of a DC shunt generator is destroyed accidentally, it may be restored by connecting its shunt field:
1. in reverse
2. to a DC source
3. to an AC source
4. to the earth

Answer 1

Correct Answer - Option 2 : to a DC source

• Residual magnetism is the small magnetic field left in the iron cores of the shunt fields when the generator is at rest
• Without it, the fields would have to be flashed with a DC current in order to start the generator generating; Hence to start the generator, it is necessary for the DC shunt generator
• Once it is destroyed, it can be restored by connecting its field finding to a DC source for a short time to magnetize the poles
• So, we need to connect the field winding to a battery (DC source)