| 摘要 |
<p>14 48,337 SINGLE-PHASE FAULT DETECTING CIRCUIT BREAKER Detection apparatus for detecting undesirable single-phase faults and overloads in a power supply circuit catering three-phase loads and for selectively tripping the load in the event of a single-phase overload or fault, uses a plug resistor as a sensing means to monitor the ripple content in an auctioneered output from three bridge rectifier circuits sensing the currents in all the three phases. A three-phase balanced overload or even a fault will cause much less ripple content than a singlephase overload condition. A circuit consisting of a resistance and capacitance in series is connected in parallel with the plug resistor, and, the voltage drop across the resistance is used to initiate tripping if the signal exceeds a predetermined magnitude, and after a selectable optional time delay. There is no need for an additional external power source to accomplish tripping. The apparatus desirably responds to single-phase faults and does not respond to motor inrush currents such as during starting.</p> |
