Factors affecting Size of Machine

Temperature and Machine size:

Size of any motor, Generator or Transformer depends on the Temperature rise in the machine. Temperature rise in the electrical machine beyond the designed value will damage the insulation of the motor. Temperature rise in the electrical machine is due to the heat generated due to losses. Current flowing in the windings in the machine generates heat. This generated heat should be dissipated else it damages the insulation of the motor.

For smaller rating motors, generators and transformers natural cooling is sufficient. However for larger rating machines heat generated will be more, hence generated heat should be removed with the help of coolents such as water either by natural circulation or forced circulation. Fans and blowers were also used to remove the generated heat.In  large alternators hydrogen cooling is employed to remove the generated heat.