Switching in Electrical Transmission and Distribution Systems
by René Smeets, Lou van der Sluis, Mirsad Kapetanovic, David F. Peelo, Anton Janssen
10 Special Switching Situations
There are several switching situations that differ from the duties standardized for switching devices in transmission and distribution systems. The most important ones are treated in this chapter.
10.1 Generator-Current Breaking
10.1.1 Introduction
Generator circuit-breakers are breakers applied at a rated voltage matching the rated voltage of a generator. They are located between the generator and step-up transformer. When no generator circuit-breaker is applied, an alternative solution is a circuit-breaker at the high-voltage side of the step-up transformer. The advantage of this solution is the less complicated simple high-current connection (generator busduct) between generator and transformer. The advantage of having a generator circuit-breaker is the possibility to connect the auxiliary plant to the medium voltage side of the (permanently energized) step-up transformer. This is depicted in Figure 10.1.
Figure 10.1 System-source and generator-source faults.
The electrical and mechanical performances of a generator circuit-breaker are very different from standard MV distribution switchgear. The only standard available worldwide that covers specifically the requirements for generator circuit-breakers is ANSI/IEEE C37.013 [1]. Apart from the ratings and other relevant characteristics, this standard contains guidelines for the type-testing ...