The primary purpose of the above discussion has been
to provide general guidelines on the application of outof-step
relaying for generators. Such protection should
be provided on the generator, if the electrical center during
a loss of synchronism condition is located in the
region from the high voltage terminals of the generators
step-up transformer down into the generator. This protection
may also be required if the electrical center is
out in the system and the system relaying is slow or can
not detect a loss of synchronism. Generator out-of-step
relaying should be capable of initiating tripping during
the first half slip cycle and when the angle between
generator and system is 90 degrees or less.
It should be emphasized that the guidelines and data
presented here are the results of generalized studies
that do not consider the effects of all types and
designes of generators and system parameters, or the
interaction effect of other generators. These effects can
only be completely determined by a study of a generator
connected to a specific system. Therefore, it is recommended
the user determine the actual loss of synchronism
characteristic for each generator, considering
the overall effects-of the system.