DC Generator Ratings

A DC generator holds four ratings.

Voltage:    Its rating of a machine is based on the insulation type and design of the machine.

Current:    Its rating is based on the size of the conductor and the amount of heat which could be dissipated in the generator.

Power:    Its rating is based on the mechanical limitations of the device which is used to turn the generator and on the thermal limits of conductors, bearings, and other components of the generator.

Speed:    Its rating, at the upper limit, is determined by the speed at that mechanical damage is complete to the machine.   A lower speed rating is based on the limit for field current (as speed increases, a higher field current are must to produce the similar voltage).