| 摘要 |
A compact and multi-functional power monitoring and circuit protection system is provided that is easily installed, used and modified, and internally derives all control and output power from the input voltages being monitored for abnormal power conditions. The functionality of all desired power monitoring and sensing devices is integrated into one unit controlled by a microprocessor. This substantially reduces the number of parts and control wiring required to achieve adequate power monitoring and circuit protection, and reduces the assembly and installation time. The integrated system uses only one set of voltage input wires, one set of current input wires, one set of blown fuse input wires and one output pair of wires to the power disconnect switch's shunt trip. Circuitry is provided to select one of the three power phases being monitored such that one of the three phases is always available to power the system. Control voltages for controlling the shunt trip and external circuits using output relays (to illuminate pilot lights, bell alarms, etc.) are also provided onboard the unit. A blown fuse detection circuit uses solid-state devices in lieu of replaceable trigger fuses. The unit can be instantly reset itself after a blown fuse condition in a power disconnect switch has been rectified.
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