一台220伏的并励直流电动机,运行时转速忽高忽低,高转速的持续时间较短,一般为3秒钟左右,并出现“飞车”现象,但电机多数时间处于正常运行状态,而且转速高低的变化也没有规律。对此,进行故障检测如下。 (1)用500伏兆欧表对励磁回路进行通断检查,未发现断路现象。 (2)在励磁回路接上电压表和电流表(如图所示)。发现每当电机转速出现“飞车”时,电压正常,励磁电流却很小,接着慢慢地回复到正常值,电机转速随之恢复正常。 A 220 volt DC shunt motor, running speed fluctuated, high speed short duration, usually about 3 seconds, and the “flying” phenomenon, but the motor most of the time in normal operation, and No change in the speed of the law. In this regard, fault detection is as follows. (1) with 500 V megger on the excitation circuit on-off inspection, did not find the phenomenon of open circuit. (2) Connect the voltmeter and ammeter to the excitation circuit (as shown). Found whenever the motor speed “flying”, the voltage is normal, the excitation current is very small, then slowly return to normal, the motor speed then returned to normal.