| 摘要 |
The proposed device for protection against leakage currents in mains with an insulated neutral contains a direct-current source, a measuring circuit between the phase wires of the mains and the earthing point, a unit for monitoring current in the measuring circuit, a pulse generator, a power-supply unit, an actuating relay, and a relay for monitoring the mains voltage. The measuring circuit contains a three-phase smoothing inductance coil and a three-phase compensating inductance coil, which are connected in series, an isolating capacitor, and a resistor. The power-supply unit and the direct-current source are connected in series and inserted in the measuring circuit. One of the power terminals of the unit for monitoring current in the measuring circuit is connected to the common point of the power-supply unit and the direct-current source, and the other terminal is connected to the second terminal of the power-supply unit. The input of the unit for monitoring current in the measuring circuit is connected to the terminal of the isolating capacitor via an integrating circuit and a resistor. The normally open contacts of the actuating relay are connected in parallel to the isolating capacitor, and the normally closed contacts are connected in parallel to the resistor in the measuring circuit.
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