Measurement of rotor temperatures of a 500MW turbine generator with unbalanced loading

The paper describes tests made on a large turbine generator to determine the effects of unbalanced stator currents on rotor surface heating. The method of testing is described, and results are given for both continuous and transient unbalanced loading. It is shown that certain points on the rotor can be subjected to unacceptably high temperatures for what were previously considered modest levels of unbalanced loading. Examples of damage which can result to rotors with a widely used form of construction are given, and techniques which can increase the negative-sequence capability are described.