| 摘要 |
DC current fed, preferably accumulator-driven, power plant for generating an AC voltage V2. The power plant comprises a DC current fed oscillator circuit KR1, C1, C2 for generating AC current pulses to the primary winding of a transformer TR for stepping up the said AC current pulses to suitable AC voltage on the secondary winding of the transformer TR. Sensor circuits D11, D12, R23, OPT1 detecting a difference between currents in each secondary lead of the transformer, a current between each secondary lead and earth and a combination of the said currents, are used to detect earth faults in the secondary winding of the transformer TR. A control circuit OPT1/2, C14, R24 etc connected to the said sensor circuits D11, D12, R23, OPT1/1 is used to disconnect the secondary voltage of the transformer TR in the event of earth faults in the secondary winding of the transformer TR. The said control circuit is controlled by a time circuit C14, R24 which is arranged to determine the time for reconnection of the secondary voltage of the transformer TR after this has been disconnected due to an earth fault. <IMAGE> |
