| 摘要 |
<p>A switching device for the protection of direct current devices such as accumulators, direct current machines and direct current devices, against for example excess current, excess temperature and low tension voltage. The switching device comprises first and second excess current switches. The first switch comprises a break point and a thermal and/or electromagnetic tripping device and the second switch comprises a break point and an electromagnetic tripping device having a high resistance coil. The break point of the first switch is connected in parallel with the tripping device of the second switch. When an excess current occurs, the break point of the first switch opens, leaving the tripping device of the second switch in circuit and this opens the break point of the second switch. The device further includes an electronic control circuit having at least one transducer for monitoring changes in at least one parameter of the direct current device to be protected. The circuit controlling the gating-on of a thyristor which, when gated-on, trips the first and second switches. The control circuit may include a resistance thermometer for monitoring a temperature in the device which is compared with a nominal temperature and/or means for monitoring the voltage across the device and comparing it with a nominal voltage.</p> |
