The disclosure is directed to a detection device for detecting a fault current (I.sub.fault) at a PV generator and/or at DC lines of a PV installation assigned to the PV generator. The PV generator has at least one first PV string and a second PV string, which are connected to a PV inverter of the PV installation via in each case two DC lines. In this case, the detection device has at least one current transformer and an evaluation circuit connected to the at least one current transformer. The current transformer can be used jointly by the first PV string and the second PV string, wherein a measurement signal of the jointly usable current transformer represents a difference between a first summation current (I.sub.sum,1) flowing from the first PV string towards the ground potential (PE) and a second summation current (I.sub.sum,2) flowing from the second PV string towards the ground potential (PE). The fault current (I.sub.fault), when it arises, is a part of the first summation current (I.sub.sum,1) and/or the second summation current (I.sub.sum,2). The disclosure also includes a PV inverter having a corresponding detection device and also a method for detecting a fault current (I.sub.fault).

A fail-safe operating method for a decentralized power generation plant DG includes determining a leakage capacitance of a generator of the DG before connecting the DG. The method also includes comparing the determined leakage capacitance with a predetermined first limit value, and connecting the DG to a grid only if the determined leakage capacitance is smaller than the predetermined first limit value. A decentralized power generation plant is configured to perform the method.

A method for leakage current compensation in a photovoltaic system includes determining a reference current flowing from at least one current-carrying line under voltage via a capacitor to earth, and generating a compensation current, having a phase and a frequency of the reference current, and having an amplitude adjusted by a negative scaling factor based on the reference current. The method further includes determining a current sum using a differential current sensor for at least a portion thereof, wherein the addends of the current sum are the currents through a complete set of current-carrying lines and the compensation current, minimizing the determined current sum by adjusting the scaling factor, and routing the compensation current through at least one other differential current sensor, such that the compensation current compensates a leakage current component of a differential current monitored by the other differential current sensor. A related device and system is also disclosed.

A fail-safe operating method for a decentralized power generation plant DG includes determining a leakage capacitance of a generator of the DG before connecting the DG. The method also includes comparing the determined leakage capacitance with a predetermined first limit value, and connecting the DG to a grid only if the determined leakage capacitance is smaller than the predetermined first limit value. A decentralized power generation plant is configured to perform the method.

The present invention provides a semiconductor integrated circuit for detecting leakage current to determine whether an electric leakage occurs in an electric line based on an induced voltage input from a leakage current detection unit 20 installed in the electric line, and an earth, leakage circuit breaker having the semiconductor integrated circuit. A semiconductor integrated circuit 100 for detecting leakage current includes: a signal amplification unit 110 configured to amplify the induced voltage; an interruption determination unit 130 configured to compare an output voltage output from the signal amplification unit with a preset reference voltage, and output an interruption signal for interrupting a power supply to the electric line; a flare current stabilization (FCS) circuit 150 for a signal amplification unit connected to the signal amplification unit; and a flare current stabilization (FCS) circuit 170 for an interruption determination unit connected to the interruption determination unit.

A semiconductor integrated circuit for leak current detection which outputs an interruption signal to cut off electrical power supplied by a power supply to an electric line if a leakage current occurs including a leakage current processing unit and an output unit configured to output the interruption signal. The leakage current processing unit includes: a zero-power supply voltage detector; a counter when the power supply voltage pulse signal is input; a zero-input induction voltage detector configured to output a leakage current pulse signal whenever the input induction voltage becomes 0 V; a counter latch configured to latch a count value supplied by the counter and output the latched count value; an output induction voltage setting unit configured to calculate an output induction voltage; and a comparator configured to compare the output induction voltage with a predetermined trip level.

The present invention provides a semiconductor integrated circuit for detecting leakage current to determine whether an electric leakage occurs in an electric line based on an induced voltage input from a leakage current detection unit 20 installed in the electric line, and an earth, leakage circuit breaker having the semiconductor integrated circuit. A semiconductor integrated circuit 100 for detecting leakage current includes: a signal amplification unit 110 configured to amplify the induced voltage; an interruption determination unit 130 configured to compare an output voltage output from the signal amplification unit with a preset reference voltage, and output an interruption signal for interrupting a power supply to the electric line; a flare current stabilization (FCS) circuit 150 for a signal amplification unit connected to the signal amplification unit; and a flare current stabilization (FCS) circuit 170 for an interruption determination unit connected to the interruption determination unit.

A fail-safe operating method for a decentralized power generation plant DG includes determining a leakage capacitance of a generator of the DG before connecting the DG. The method also includes comparing the determined leakage capacitance with a predetermined first limit value, and connecting the DG to a grid only if the determined leakage capacitance is smaller than the predetermined first limit value. A decentralized power generation plant is configured to perform the method.

A semiconductor integrated circuit for leak current detection which outputs an interruption signal to cut off electrical power supplied by a power supply to an electric line if a leakage current occurs including a leakage current processing unit and an output unit configured to output the interruption signal. The leakage current processing unit includes: a zero-power supply voltage detector; a counter when the power supply voltage pulse signal is input; a zero-input induction voltage detector configured to output a leakage current pulse signal whenever the input induction voltage becomes 0 V; a counter latch configured to latch a count value supplied by the counter and output the latched count value; an output induction voltage setting unit configured to calculate an output induction voltage; and a comparator configured to compare the output induction voltage with a predetermined trip level.

A dangerous, higher-frequency (>1 kHz) earth fault current in an electrical drive system operated in an electrical grid and having a power converter and an electrical drive machine can be prevented by producing a common-mode voltage with a defined common-mode voltage component in the power converter at a selected low frequency (<1 kHz); in the event of an earth fault in the electrical drive system, flowing at the selected low frequency a common-mode current component of a common-mode current through a predominantly ohmic conductor-to-earth impedance on the basis of the defined common-mode voltage component; measuring a total common-mode current in one of several current circuits of the electrical drive system; determining from the total current the common-mode current component; and when the common-mode current component reaches a reference value, disconnecting the electrical drive system from the electrical grid.