It depends on the application. If it is running in island mode, not connected to utility grid or other generators, and not service life-safety equipment, I'd suggest 110% and 90% with a suitable time delay or inverse time curve.
Irrespective of grid or isolated operation, set your relays to 115% and 85% inverse characteristics for O/V and U/V respectively. Check with your type of connected load for time setting.
Suggestion: The emergency generators are usually not designed with over/under voltage protection since their intent is to function in spite of various load side adversities, to supply power to emergency loads.
This is an emergency lighting system that supplies emergency power for egress lighting loads on an offshore floating facility.I presently have it set at 110 % and 90% respectively.I was pretty sure I was close but wanted to get some feedback from other idustries.I do occassionally sync to my normal power which is three 4160 4750 KW genset's but only for 5 seconds.Anyway thanks for the feedback guys.
