A circuit system for measuring an electrical voltage. The circuit system includes a voltage divider, an integrating element and an evaluating unit. The voltage divider receives, at an input, a first signal that represents the electrical voltage to be measured, and has a first switching element and a second switching element, and is capable of assuming a first state, in which the first switching element is conductive and the second switching element is non-conductive, and a second state in which the first switching element is non-conductive and the second switching element is conductive, and outputs a second signal at an output that is situated between the first switching element and the second switching element. The integrating element is designed to receive the second signal and to output a third signal. The evaluating unit being set up to accept and to evaluate the third signal in order to determine a value for the electrical voltage.

A circuit system for measuring an electrical voltage. The circuit system includes a voltage divider, an integrating element and an evaluating unit. The voltage divider receives, at an input, a first signal that represents the electrical voltage to be measured, and has a first switching element and a second switching element, and is capable of assuming a first state, in which the first switching element is conductive and the second switching element is non-conductive, and a second state in which the first switching element is non-conductive and the second switching element is conductive, and outputs a second signal at an output that is situated between the first switching element and the second switching element. The integrating element is designed to receive the second signal and to output a third signal. The evaluating unit being set up to accept and to evaluate the third signal in order to determine a value for the electrical voltage.

A measuring system for detecting a physical parameter, includes a measuring sensor for detecting the physical parameter, which sensor has a first, second and at least one third terminal. The measuring system also includes a first power supply unit for outputting electrical energy to the measuring sensor with a first voltage with respect to a first ground potential via the first and the second terminal, and a second power supply unit for outputting electrical energy to the measuring sensor with a second voltage with respect to a second ground potential via the third and the second terminal or a fourth terminal. The first ground potential can differ from the second ground potential at least temporarily. The first power supply unit includes an additional voltage source via which the second terminal is electrically connected to the first ground potential.

A measuring system for detecting a physical parameter, includes a measuring sensor for detecting the physical parameter, which sensor has a first, second and at least one third terminal. The measuring system also includes a first power supply unit for outputting electrical energy to the measuring sensor with a first voltage with respect to a first ground potential via the first and the second terminal, and a second power supply unit for outputting electrical energy to the measuring sensor with a second voltage with respect to a second ground potential via the third and the second terminal or a fourth terminal. The first ground potential can differ from the second ground potential at least temporarily. The first power supply unit includes an additional voltage source via which the second terminal is electrically connected to the first ground potential.

A voltage level detector includes a voltage divider that generates a first division voltage and a second division voltage. A first comparator compares any one of the first and second division voltages with a reference. A second comparator compares the other of the first and second division voltages with the reference. A first switch converts a connection path between the first and second division voltages and the first and second comparators based on a clock signal. A determination circuit determines, based on a first comparison signal and a second comparison signal, whether the voltage level detector is normal. A second switch converts a connection path between the first and second comparison signals and input terminals of the determination circuit based on the clock signal.

A voltage level detector includes a voltage divider that generates a first division voltage and a second division voltage. A first comparator compares any one of the first and second division voltages with a reference. A second comparator compares the other of the first and second division voltages with the reference. A first switch converts a connection path between the first and second division voltages and the first and second comparators based on a clock signal. A determination circuit determines, based on a first comparison signal and a second comparison signal, whether the voltage level detector is normal. A second switch converts a connection path between the first and second comparison signals and input terminals of the determination circuit based on the clock signal.

The present invention relates to a device and a method for diagnosing a switch using voltage distribution, and more particularly, to a device and a method for diagnosing a switch using voltage distribution, which connect one or more resistors connected in series with the switch in parallel and calculate voltage applied to one resistor among one or more resistors by using the voltage distribution to diagnose a state of the switch based on the calculated voltage, in order to diagnose the state of the switch positioned on a cathode power supply line connecting a battery and a load.

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.

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.

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.