Members of the "Working Group on Protective Relaying for Pumped Storage Hydro Units"; N. 0. Engebretson

The protection of pumped storage units, although essentially the same as conventional generators, requires additional relays and close attention to the phase relationship of relay inputs because of the unusual modes of operation. This paper reviews the various protective devices that may be employed in the protection of a pumped storage unit, which includes the generator/motor, phase reversing switches, circuit breakers, main transformer, and the connections between these components. It does not include protective devices associated with auxiliary equipment such as station service transformers, starting motors, static converter starting devices, etc.