A supply device for supplying electricity to at least one consumer includes: a primary power supply in which there is a first fuel cell device having a first performance; a voltage transformer which connects the primary power supply to a secondary power supply having a battery; and a measuring device for detecting an insulation resistance of the primary power supply and/or of the secondary power supply. A second fuel cell device having a second performance is connected in series with the first fuel cell device in the primary power supply, wherein a bridge circuit comprising a switch is connected in parallel with each of the fuel cell devices and wherein the switches of the bridge circuits can be switched in accordance with the detected insulation resistance. A fuel cell vehicle and a method for limiting voltage in a supply device are also provided.

An earth fault detection apparatus includes a switch group configured to switch between a first measurement path including a battery and a capacitor, and a second and third measurement paths including the battery, a positive/negative-side insulation resistance, and the capacitor; a reference resistance and a test switch; and a control unit calculating a first reference value based on each charging voltage in a case where the test switch is opened and the capacitor is charged, and calculating the insulation resistance with reference to a conversion map created to correspond to an electrostatic capacitance between a power supply line and ground, wherein the control unit calculates a second reference value based on each charging voltage in a case where the test switch is closed and the capacitor is charged for a shorter time, and estimates the electrostatic capacitance with reference to a predetermined test conversion map.

An earth fault detection apparatus includes a switch group configured to switch between a first measurement path including a battery and a capacitor, a second measurement path including the battery, a negative-side insulation resistance, and the capacitor, a third measurement path including the battery, a positive-side insulation resistance, and the capacitor; and a control unit configured to calculate a reference value, based on each charging voltage of the capacitor in each measurement path, and configured to calculate an insulation resistance with reference to a predetermined conversion map, in which the conversion map includes a conversion map corresponding to a capacitance of the capacitor, and the control unit estimates the capacitance of the capacitor, and refers to the conversion map corresponding to the capacitance of the capacitor that has been estimated.

An apparatus includes a first analog-to-digital converter configured to measure a first reference voltage and a third reference voltage. The apparatus also includes a second analog-to-digital converter configured to measure a second reference voltage and a fourth reference voltage. The apparatus also includes a controller configured to calculate a first resistance ratio, and determine a positive high voltage associated with the positive high voltage direct current input signal based, at least in part, on the first resistance ratio. The controller is further configured to calculate a second resistance ratio, and determine a negative high voltage associated with the negative high voltage direct current input signal based, at least in part, on the second resistance ratio.

The invention relates to a method and a photovoltaic inverter (2) for determining the insulation resistance (R.sub.iso) of a photovoltaic system (1) relative to ground (PE). According to the invention, the voltage required for the measurement can be provided by the intermediate circuit (6) in the form of the intermediate circuit voltage (U.sub.Zk), and the measuring device (13) is designed to actuate an input short-circuit switch (S.sub.Boost) for short-circuiting the DC input (3) with the AC disconnector (8) open, as a result of which the intermediate circuit voltage (U.sub.Zk) can be applied to the DC input (3) in the reverse direction, and the measuring device (13) is configured to record measured voltages (U.sub.M1, U.sub.M2) with the switch (S.sub.iso) of the voltage divider (14) open and closed, and to determine the insulation resistance (R.sub.iso) from the measured values of the two measured voltages (U.sub.M1, U.sub.M2) recorded with the switch (S.sub.iso) of the voltage divider (14) open and closed.

To measure the resistance area product of a high resistivity layer using a microscopic multi point probe, the high resistivity layer is sandwiched between two conducting layers. A plurality of electrode configurations/positions is used to perform three voltage or resistance measurements. An equivalent electric circuit model/three layer model is used to determine the resistance area product as a function of the three measurements.

It is described an electrical installation measuring system comprising a control and measuring device configured to be installed on an electrical panel of an electrical installation and perform at least one measure of an electrical parameter of the electrical installation depending on an electrical load connected to the electrical installation and transmit command signals along a telecommunication link. The system further comprises a variable load device connectable to the electrical installation and configured to: receive the command signals from the telecommunication link; and assume a plurality of load configurations according to the command signals.

A controller (1) forms an insulation measurement path and turns on a third switch connected in parallel to a capacitor, (2) after a lapse of a first time period turns off the third switch, and (3) detects an insulation abnormality based on a voltage of the capacitor measured after a lapse of a second time period after the turning off of the third switch.

An insulation resistance inspection system for a battery module cell pouch for inspecting an insulation resistance state of a cell pouch in the battery module configured by assembling a plurality of battery cells includes: an inspection unit bringing each of a plurality of probe modules into contact with an end surface of the cell pouch to measure an insulation resistance of the cell pouch; an interface unit connected to the inspection unit to receive a signal for the measured insulation resistance of the cell pouch; and a control unit receiving the signal for the insulation resistance of the cell pouch through the interface unit to determine whether the cell pouch is in good condition or in poor condition depending on whether the signal for the insulation resistance of the cell pouch is within a normal range that is a reference of good quality.

A ground fault detection device connected to a high-voltage battery and a positive electrode side Y capacitor includes: a detection capacitor operating as a flying capacitor, a first switch and a first resistor connecting a positive electrode side of the high-voltage battery and one end of the detection capacitor in series, and a discharge circuit including at least a discharge capacitor. The discharging circuit has one end connected to the positive electrode side of the high-voltage battery and an another end connected to the negative electrode side of the high-voltage battery. The discharge circuit further includes: a fifth switch that connects one end of the discharge capacitor and the positive electrode side Y capacitor, and a second discharge resistor and an eighth switch that connect the another end of the discharge capacitor and the ground in series.