Abstract:Currently,the override trip problems commonly exist in coal mine power system.So the underground coal mine high voltage power systems are analyzed.One anti-override trip monitoring system of fiber longitudinal current differential protection is proposed based on GPS adjusting system.The system can realize sampling and full power data synchronization,realizes fault information data＇s information share.The inside and outside fault can effectively differentiates and also can quickly cut fault line selectively.It avoids large-scale power failure accidents because of override trip at underground coal mine.

Abstract:Analyzes the high and low speed conversion by common asynchronous motor, TIT, CST coupling and variable frequency motor start method of scraper conveyor at fully mechanized coal face. The problems and solved proposal of variable frequency motor are introduced on spot test and operation. The practical application shows that the operation function is good of variable frequency motor.