The present invention relates to a residual current circuit breaker, RCCB, (100) for an electrical circuit (300). The RCCB comprises a first switching device (106) and a second switching device (140) coupled in series with each other between the power supply (302) and the load (304). The first switching device (106) is configured to switch into an OFF mode, in which no current is fed to the load (304), upon detecting that a value of a current i fed to the load (304) is larger than a switching current is of the first switching device (106). The second switching device (140) is configured to switch into an ON mode, in which the load (304) is short cut, upon detecting a leakage of the current i fed to the load (304). Thereby, a novel RCCB architecture is provided. When a current leakage is detected a short cut is introduced which means that the voltage will be zero over the load and no person will be harmed by the current in the circuit. Flowever, when the load is short cut there will be a current rush in the circuit which will trigger the first switching device to break the circuit and no current will thereafter flow in the circuit. The invention also relates to a circuit comprising such a residual current circuit breaker and a corresponding method.

A fault protection arrangement may include a neutral grounding resistor, the neutral grounding resistor comprising a ground end and a non-ground end. The fault protection arrangement may include a neutral grounding resistance monitor assembly, coupled to the neutral grounding resistor, where the neutral grounding resistance monitor assembly includes a sense circuit, coupled to the ground end of the neutral grounding resistor; and an injection signal generator, arranged to generate a frequency of 240 Hz or greater.

A fault protection arrangement may include a neutral grounding resistor, the neutral grounding resistor comprising a ground end and a non-ground end. The fault protection arrangement may include a neutral grounding resistance monitor assembly, coupled to the neutral grounding resistor, where the neutral grounding resistance monitor assembly includes a sense circuit, coupled to the ground end of the neutral grounding resistor; and an injection signal generator, arranged to generate a frequency of 240 Hz or greater.

A circuit breaker is provided that may be plugged onto an electrical panel. The circuit breaker is preferably a low voltage circuit breaker in the range of 120-240 volts. The circuit breaker has an electrical clip with a curved inner surface that contacts a curved outer surface of an electrical connector on the electrical panel.

A circuit breaker is provided that may be plugged onto an electrical panel. The circuit breaker is preferably a low voltage circuit breaker in the range of 120-240 volts. The circuit breaker has an electrical clip with a curved inner surface that contacts a curved outer surface of an electrical connector on the electrical panel.

A current sense short protection circuit includes a switch unit, a current sensing unit, a detection circuit and a short detection module. The first terminal of the switch unit receives a first voltage. The control terminal of the switch unit receives a control signal. The first terminal of the current sensing unit is coupled to the second terminal of the switch unit. The second terminal of the current sensing unit receives a second voltage. The detection unit receives the second voltage and a third voltage provided by the first terminal of the current sensing unit, and generates a detection signal according to the second voltage and the third voltage. The short detection module receives the first voltage, the second voltage and the detection signal, and generates a short detection signal according to the first voltage, the second voltage and the detection signal.

A current sense short protection circuit includes a switch unit, a current sensing unit, a detection circuit and a short detection module. The first terminal of the switch unit receives a first voltage. The control terminal of the switch unit receives a control signal. The first terminal of the current sensing unit is coupled to the second terminal of the switch unit. The second terminal of the current sensing unit receives a second voltage. The detection unit receives the second voltage and a third voltage provided by the first terminal of the current sensing unit, and generates a detection signal according to the second voltage and the third voltage. The short detection module receives the first voltage, the second voltage and the detection signal, and generates a short detection signal according to the first voltage, the second voltage and the detection signal.

A protection system including: a DC power supply; a power converter that converts DC power of the DC power supply into AC power, a circuit breaker that is series-connected to an electrical path located between the DC power supply and the power converter and can open the electrical path; a DC capacitor connected to a circuit located in the power converter; a timer that counts a lapse of a predetermined length of time from turn-on of the circuit breaker; a current detector that detects current flowing in the power converter; and a protection determiner that issues an open operation command to the circuit breaker when the current detector does not detect a decrease in the current after the timer has counted a lapse of the predetermined length of time from turn-on of the circuit breaker.

A method and an apparatus for use in an earth-fault protection in a three-phase electric network, the apparatus is configured to detect a phase-to-earth fault in the network, to determine for each of the phases of the network a phase current during the fault or a change in the phase current due to the fault, to detect a faulted phase of the network, to determine an estimate of an earth-fault current on the basis of the faulted phase and the phase currents or the changes in the phase currents, to determine a zero-sequence voltage of the electric network or a change in the zero-sequence voltage, and to determine a direction of the phase-to-earth fault from the measuring point on the basis of the estimate of the earth-fault current and the zero-sequence voltage or the change in the zero-sequence voltage.

A coupling circuit (20) with switching function for coupling an insulation monitoring device (6, 6a, 6b) to an unearthed power supply system (2, 2a, 2b), consisting of a coupling module (22) or a plurality of identical coupling modules (22) connected in series, wherein the coupling module (22) has at least one switch unit (25), which comprises a coupling impedance (26), a switch (24), arranged in series to the coupling impedance (26), for mains disconnection and a control circuit (28) for controlling the switch (24), and also exactly one transformer (30) for voltage supply and for potential separation.