| 摘要 |
PURPOSE:To exactly monitor spark, by receiving spark noise and external noise with a first antenna of two electromagnetic wave receiving antennas arranged near collector rings and brushes, and external noise with a second antenna, and by finding out the difference between the both receptions. CONSTITUTION:Direct current obtained by rectifying an AC power source 12 is fed to bush rings 5 via exciting wires 14. The direct current is fed from the bush rings 5 to collector rings 1, 2 via lead wires 4 and brushes 3. Near the bush rings 5, an electromagnetic wave receiving antenna 7 is set, and noise due to spark generated by the brushes 3 and external noise are received. Outside a shielded locker section 6, an antenna 8 receiving the external noise only is set. The outputs of the antennas 7, 8 are input to a noise detecting section via a connector 9, and when the output different is a specified value or more, then an alarm 11 is driven. As a result, the spark monitoring of high reliability is performed. |
