| 摘要 |
An A.C. solid state power controller for controlling the current through a load 250 from an alternating current source 12, includes a diode bridge rectifier 70-100 with its direct current output connected to a solid state switch 130, such as a MOSFET or a bipolar transistor, that is controlled by control signals synchronized to the A.C. source. The control signals are provided, such as from an optocoupler 40, to control the solid state switch and the load current. Overload, short circuit, and low A.C. line voltage conditions are sensed by protection circuit 170 which signal the optocoupler to turn off the solid state switch and, thus, the load current. A fast turn off time, in the range of a few microseconds, is achieved which, together with the rectifier and solid state switch configuration, provides a power controller which is resistant to short circuit and overload destruction present in conventional A.C. solid state circuit breakers and power control devices. After detecting an overcurrent the protection circuit 170, which is described in detail (Fig 6) resets the current and if overload continues the solid state switch 130 is turned off. The number of repeated attempts to restore current is determined by a counter (814, Fig 6). <IMAGE>
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