Dynamic testing of frequency relays

Frequency relays are often applied on power systems either to protect generation equipment or provide load shedding capabilities. Accurate setting and operation of these relays is essential in the proper coordination of the power system equipment. Dynamic testing provides a method of assuring the proper operation of frequency relays. Along with this testing is a myriad of complexities and confusion. Dynamic tests are not always as straightforward as one might think, especially when the results are not as anticipated. The methods of testing, type of test equipment used, and the specific relay measuring techniques all play a significant role in the dynamic testing results. This paper discusses the intricacies of dynamic frequency testing along with the differences between test equipment and frequency relays and how these differences affect the testing results. A sampling of four frequency relays was tested (three solid-state devices and one electromechanical), each using four different test sets. Results of each are discussed.