In a D.C. generator all of the following could be the effects of iron losses except

The correct answer is D. Rise in temperature of ventilating air.

Iron losses are the losses that occur in the magnetic core of a DC generator. These losses are caused by the eddy currents and hysteresis losses that occur in the core. Eddy currents are caused by the changing magnetic field in the core. Hysteresis losses are caused by the reversal of the magnetic field in the core.

Iron losses cause the core to heat up. This heating can cause the generator to become less efficient. It can also cause the generator to overheat and damage the insulation.

The rise in temperature of the ventilating air is not caused by iron losses. The ventilating air is used to cool the generator. The rise in temperature of the ventilating air is caused by the heat generated by the generator.

The other options are all caused by iron losses.

A. Loss of efficiency: Iron losses cause the generator to become less efficient. This is because the iron losses cause the core to heat