| 摘要 |
PURPOSE:To rapidly and effectively detect a malfunction by monitoring the slide contact state of a ground brush by the voltage of a high impedance circuit mounted on a brush and the current of a low impedance circuit. CONSTITUTION:A brush 6 is grounded to the ground E through a switch 9 and a low impedance circuit 10, and when the current flowed to the circuit becomes the prescribed value or higher, an alarm unit 11 is operated. When the brush 6 is grounded to the ground E through a high impedance circuit 12, the switch 9 is opened and the voltage of the high impedance circuit 12 becomes the prescribed value or higher or zero at the circuit 10 opening time, an alarm unit 13 is operated. A brush 7 is contacted with the ground through a switch 14 and a low impedance circuit 15. When the difference between the current flowed to the circuit 15 and the current flowed to the circuit 10 becomes the prescribed value or higher, an alarm unit 16 is operated. |
