Directing against hidden troubles existing in typical control logics of main protection functions for steam turbines of many large-capacity thermal power units in Henan province

namely malfunctions and miss operation

improments of protection control logics for high metal temperature of steam turbine bearings

too fast temperature dropping of main steam and reheated steam

large vibration of bearings

large displacement of shaft

over-speed

and large interlock among turbine

boiler

and generators etc.

have been carried out

measures for enhancing the reliability of protection control logics for steam trubines have been put forward from aspects of power supply allocation

on-line test

supervision

and alarm etc.for protective functions.Application shows that the remarkable enhancement of reliability for protection control has been obtained after improvement.