Imperfect brush contact
Field resistance less than the critical resistance
generator fails to build up the probable cause could not be A. Imperfect brush contact B. Field resistance less than the critical resistance C. No residual magnetism in the generator
Faulty shunt connections tending to reduce the residual magnetism
Answer is Wrong!
Answer is Right!
The correct answer is: A. Imperfect brush contact.
The other options are all possible causes of a D.C. generator failing to build up.
- Field resistance less than the critical resistance: This means that the field current is too low, which can be caused by a faulty field winding or a loose connection.
- No residual magnetism in the generator: This means that the generator does not have any residual magnetism, which is required to start the build-up process. This can be caused by a faulty field winding or a loss of power.
- Faulty shunt connections tending to reduce the residual magnetism: This means that the shunt connections are not making good contact, which can reduce the amount of residual magnetism in the generator. This can be caused by a loose connection or a faulty shunt winding.
Imperfect brush contact is the most likely cause of a D.C. generator failing to build up because it is a common problem that can easily be overlooked. If the brushes are not making good contact with the commutator, then the current will not flow properly and the generator will not build up.
The other options are less likely causes of a D.C. generator failing to build up, but they should still be checked if the generator is not working properly.