| 摘要 |
A circuit for providing immunity from noise and nuisance tripping for a ground fault protective device having two or more electrical contacts connected to an electrical distribution system having two or more conductors. The circuit has means for tripping the electrical contacts of the ground fault protective device connected to the first two conductors. A power supply is connected to the second of the two conductors and the tripping means. The tripping means are a selected impedance for limiting current to the power supply when noise voltage in the electrical distribution systems exceeds a predetermined second level so that energy dissipated by the power supply does not exceed the power supply's capacity. The power supply has means for clipping the noise voltage when it exceeds the predetermined second level. Ground fault responsive means for producing a fault signal are electrically connected to the two conductors. Switching means connected to the ground fault responsive means and responsive to the fault signal, and also connected to the power supply and the means for tripping and responsive to a predetermined first level of noise voltage higher than the predetermined second level of noise voltage, are provided as well. These switching means cause the means for tripping to be energized by the power supply when it receives the fault signal from the ground fault responsive means. |
