| 摘要 |
<p>A current limiting device for connection in use between an AC mains power source and a load. The unit has a controllable semi-conductor device Q3 in the current carrying path between the source and the load. Also in the path is a sensing resistor R2. The unit also has circuit means responsive to the voltage developed across the sensing resistor R2. The circuit means acts to turn off the semi-conductor device in the event that the current flow in the load exceeds a predetermined level. The current flow is permitted to exceed the predetermined level for a period of time, the period being less for higher excess currents and turn off is virtually instantaneous in the event of a short circuit of the load or a sudden or very high current flow. The semi-conductor device may be turned back on after turn off, but only after a predetermined time has elapsed and not until the load is disconnected.</p> |
