| 摘要 |
PURPOSE:To share an earth for frame of a power device for common use with an earth for communication, by separating a commercial power source in case AC power system is earthed, and by feeding the current from an isolated neutral or high-resistance earthed neutral auxiliary power source. CONSTITUTION:When a commercial power source 1 is normal, the power is supplied to a communication system through an earth leakage breaker 9, a switching device 3 and a power device 4. When the commercial power source 1 is interrupted, a battery 5 discharges the current until the auxiliary power source 2 gets to leading. Then the current is fed to the communication system through the switching device 3 and the power device 4. In case earthing occurs in the power device, the earth leakage breaker 9 actuates to separate the commercial power source 1 just as in the same operation as in the interruption of service to the commercial power source 1. The output of the auxiliary power source 2 being isolated neutral or high-resistance earthed neutral, no appreciable leakage current will flow. |
