A voltage sensing circuit uses a voltage divider for providing a sense signal indicating the voltage across a circuit component. A current injector is used for injecting current to the sensing terminal. A sense signal is obtained with no current injection, to determine if a fault is present. The sensing terminal is coupled to the external circuit component via a voltage clamping component. A further sense signal is obtained in response to the injection of current. By comparing the sense signal in response to the injected current and a clamping voltage of the voltage clamping component, it can then be determined if the fault is caused by the circuit component or by the voltage divider.

A voltage-divider circuit, including: a network of discrete resistors defining T tiers of resistors, where T≥2, the T tiers comprising first and subsequent tiers, the Xth tier including at least one Xth-tier resistor where X=1, and the Xth tier including at least two Xth-tier resistors for each value of X in the range 2≤X≤T, wherein, for each value of X in the range 1≤X<T: each Xth-tier resistor is connected between a pair of nodes of the voltage-divider circuit at which a relatively high and low voltage signal are provided, respectively; at least one Xth-tier resistor is implemented as a subdivision network of discrete resistors; and for each Xth-tier resistor implemented as a subdivision network, that subdivision network includes a main resistor connected in series with a corresponding auxiliary resistor, that main resistor implemented as a base resistor connected in parallel with a series connection of a plurality of X+1th-tier resistors.

A voltage-divider circuit, including: a network of discrete resistors defining T tiers of resistors, where T≥2, the T tiers comprising first and subsequent tiers, the Xth tier including at least one Xth-tier resistor where X=1, and the Xth tier including at least two Xth-tier resistors for each value of X in the range 2≤X≤T, wherein, for each value of X in the range 1≤X<T: each Xth-tier resistor is connected between a pair of nodes of the voltage-divider circuit at which a relatively high and low voltage signal are provided, respectively; at least one Xth-tier resistor is implemented as a subdivision network of discrete resistors; and for each Xth-tier resistor implemented as a subdivision network, that subdivision network includes a main resistor connected in series with a corresponding auxiliary resistor, that main resistor implemented as a base resistor connected in parallel with a series connection of a plurality of X+1th-tier resistors.

The invention relates to a device (D) for detecting a fault in an electrical network (1), comprising at least one electrical quipment (E) which is electrically connected to a first power conductor (C1) and to a second power conductor (C2), the electrical network (1) being provided with a common conductor (Cc). The device comprises a first measuring member (O1) of the common mode voltage present on the power conductors (C1, C2) and a second measuring member (O2) of a current flowing in the power conductors (C1, C2). The device also comprises a calculator (UP) configured to determine over a determined observation period a mixed energy (E.sub.mix) transported in the measurement region from the first variable (V.sub.res) and the second variable (I.sub.net). The invention also relates to an equipment, a localization system and a method for detecting a fault in an electrical network.

A method and a photovoltaic inverter for determining the insulation resistance of a photovoltaic system relative to ground are provided. The voltage required for the measurement can be provided by an intermediate circuit in the form of an intermediate circuit voltage and a measuring device is designed to actuate an input short-circuit switch for short-circuiting a DC input with an AC disconnector open, as a result of which the intermediate circuit voltage can be applied to the DC input in the reverse direction. The measuring device is configured to record measured voltages with a switch of a voltage divider open and closed, and to determine the insulation resistance from the measured values of the two measured voltages recorded with the switch of the voltage divider open and closed.

A method and a photovoltaic inverter for determining the insulation resistance of a photovoltaic system relative to ground are provided. The voltage required for the measurement can be provided by an intermediate circuit in the form of an intermediate circuit voltage and a measuring device is designed to actuate an input short-circuit switch for short-circuiting a DC input with an AC disconnector open, as a result of which the intermediate circuit voltage can be applied to the DC input in the reverse direction. The measuring device is configured to record measured voltages with a switch of a voltage divider open and closed, and to determine the insulation resistance from the measured values of the two measured voltages recorded with the switch of the voltage divider open and closed.

A monitoring device for monitoring an impedance of a protective conductor. The monitoring device has a first voltage divider for connection to a voltage source including a series connection to a first resistor and a second resistor. The second resistor has a resistance value which corresponds to a threshold value for the impedance of the protective conductor. A second voltage divider includes a series connection to a third resistor and a bridge diode and a connection to the first resistor at a first end of the third resistor and connectable to a second end of the third resistor and to the protective conductor. A measuring device is provided for the detection of a bridge voltage between a first node and a second node if the impedance of the protective conductor is greater than the value of the second resistor.

A monitoring device for monitoring an impedance of a protective conductor. The monitoring device has a first voltage divider for connection to a voltage source including a series connection to a first resistor and a second resistor. The second resistor has a resistance value which corresponds to a threshold value for the impedance of the protective conductor. A second voltage divider includes a series connection to a third resistor and a bridge diode and a connection to the first resistor at a first end of the third resistor and connectable to a second end of the third resistor and to the protective conductor. A measuring device is provided for the detection of a bridge voltage between a first node and a second node if the impedance of the protective conductor is greater than the value of the second resistor.

A system and method for compensating for drift in a switch gear voltage sensor. The system includes a circuit, and an electronic processor. The circuit is configured to receive a first signal from a first capacitor of the voltage sensor and receive a second signal from a second capacitor of the voltage sensor. The circuit is further configured to generate a third signal and a fourth signal based on the first signal and the second signal. The electronic processor is configured to receive the third signal and the fourth signal and determine an angular frequency, a phase difference, a resistance value, a voltage across a compensation capacitor, an initial gain, a capacitance of the second capacitor, a capacitance and a voltage of the compensation capacitor, and a final gain.

A method and a photovoltaic inverter determines the system capacitance of a photovoltaic system relative to ground. The voltage required for the measurement can be provided by the intermediate circuit in the form of the intermediate circuit voltage, and the measuring device is designed to actuate an input short-circuit switch for short-circuiting the DC input with the AC disconnector open, as a result of which the intermediate circuit voltage can be applied to the DC input in the reverse direction, and the measuring device is configured to determine the system capacitance from the temporal waveform of the measured voltage after the switch of the voltage divider is closed.