Supersedes C37.106-1987 (R1992). This guide has been prepared to assist the protection engineer in applying relays for the protection of generating plant equipment from damage caused by operation at abnormal frequencies including overexcitation.

The WG will revise ANSI/IEEE C37.106 to better reflect current utility practices and manufacturers' current recommendations regarding turbine-generator underfrequency protection schemes.

Existing underfrequency protective relaying schemes in the Guide will be reviewed and revised to reflect current relay technologies, in light of the possibilities offered by present digital multi-function relay packages.