Purpose and Scope
This volume is intended to fill the need for practical information concerning the temperature and mechanical
and electrical overload limits of rotating electric equipment such as generators and large motors. Rotating
electrical equipment cannot be overloaded on the same basis as transformers and is not as able to stand
short-time overloads. This is largely because equipment cooled by air does not have the heat transfer ability
which the higher thermal conductivity of insulating oil gives to transformers; also, the windings in rotating
equipment are confined in slots in the steel and are subject to temperature expansion problems. For any
abnormal loading of generators, the electrical, mechanical, and thermal characteristics must be evaluated to
determine the machines limitations. Machines should not be loaded beyond the manufacturer's defined
overload capability unless a complete study of the unit has been made to define safe limits. Additional tests
might have to be conducted to substantiate the possibilities for higher-than-rated loadings.
and electrical overload limits of rotating electric equipment such as generators and large motors. Rotating
electrical equipment cannot be overloaded on the same basis as transformers and is not as able to stand
short-time overloads. This is largely because equipment cooled by air does not have the heat transfer ability
which the higher thermal conductivity of insulating oil gives to transformers; also, the windings in rotating
equipment are confined in slots in the steel and are subject to temperature expansion problems. For any
abnormal loading of generators, the electrical, mechanical, and thermal characteristics must be evaluated to
determine the machines limitations. Machines should not be loaded beyond the manufacturer's defined
overload capability unless a complete study of the unit has been made to define safe limits. Additional tests
might have to be conducted to substantiate the possibilities for higher-than-rated loadings.