Methods and devices for insulation monitoring of an ungrounded IT power supply system having at least two phase conductors includes determining an insulation resistance separately for each phase conductor using a separate response value. In one embodiment of the invention, relevant current and voltage distributions are calculated. In another embodiment, a change time window is set within which a second response value is activated. In yet another embodiment, an option of shutting down/continuing operation of the IT power supply system is offered.

Methods and devices for insulation monitoring of an ungrounded IT power supply system having at least two phase conductors includes determining an insulation resistance separately for each phase conductor using a separate response value. In one embodiment of the invention, relevant current and voltage distributions are calculated. In another embodiment, a change time window is set within which a second response value is activated. In yet another embodiment, an option of shutting down/continuing operation of the IT power supply system is offered.

A method for identifying the existence of a failure of a relay device in an electrical power supply system of a device to be supplied with power, the power supply system comprising at least one power generator configured to generate a power supply signal and a load comprising at least one relay device; the power generator comprising a frequency variator; each relay device comprising a quadripole and at least one antenna linked to the quadripole. The identification method comprises the following steps: a) selecting a characteristic frequency, b) determining the impedance of the load, then when the supply signal has the selected characteristic frequency, c) repeating steps a) and b) for several distinct characteristic frequencies, d) identifying the existence of a failure from several impedances determined for different characteristic frequencies.

A method for identifying the existence of a failure of a relay device in an electrical power supply system of a device to be supplied with power, the power supply system comprising at least one power generator configured to generate a power supply signal and a load comprising at least one relay device; the power generator comprising a frequency variator; each relay device comprising a quadripole and at least one antenna linked to the quadripole. The identification method comprises the following steps: a) selecting a characteristic frequency, b) determining the impedance of the load, then when the supply signal has the selected characteristic frequency, c) repeating steps a) and b) for several distinct characteristic frequencies, d) identifying the existence of a failure from several impedances determined for different characteristic frequencies.

Provided are a failure determination device and method for a rotating machine control device, which are capable of detecting failure of a sensor configured to detect a rotational position of a rotating machine while the rotating machine is in operation. A rotation angle estimator calculates a rotation angle estimation value. A relationship between the rotation angle estimation value (θest), and a first angle detection value (θ1) and a second angle detection value (θ2), which are obtained from output signals of angle sensors configured to detect a rotational position of a rotating machine, is monitored while the rotating machine is in operation. In this manner, failure of the angle sensors, which are configured to detect the rotational position of the rotating machine, can be always detected even while the rotating machine is in operation.

Provided are a failure determination device and method for a rotating machine control device, which are capable of detecting failure of a sensor configured to detect a rotational position of a rotating machine while the rotating machine is in operation. A rotation angle estimator calculates a rotation angle estimation value. A relationship between the rotation angle estimation value (θest), and a first angle detection value (θ1) and a second angle detection value (θ2), which are obtained from output signals of angle sensors configured to detect a rotational position of a rotating machine, is monitored while the rotating machine is in operation. In this manner, failure of the angle sensors, which are configured to detect the rotational position of the rotating machine, can be always detected even while the rotating machine is in operation.

In a power supply system, a high-side (HS) insulated-gate bipolar transistor (IGBT) has a first collector, a first gate, and a first emitter. A low-side (LS) IGBT has a second collector coupled to the first emitter, a second gate, and a second emitter. A gate drive circuit is coupled to the first gate of the HS IGBT and the second gate of the LS IGBT. A control circuit is coupled to the gate drive circuit. The control circuit is configured to control the gate drive circuit for biasing the HS IGBT to a HS saturation, and determine a HS degradation of the HS IGBT based on a HS digitized gate voltage of the HS IGBT in the HS saturation.

An insulation impedance detection method includes: An inverter injects a first common-mode voltage into an alternating current side, where the first common-mode voltage is divided by an alternating current grounding insulation impedance of an alternating current cable and a direct current grounding insulation impedance of a photovoltaic unit. The inverter can obtain an impedance value of the alternating current grounding insulation impedance based on the first common-mode voltage, a voltage divided by the alternating current grounding insulation impedance for the first common-mode voltage (a second common-mode voltage on the alternating current grounding insulation impedance), and an impedance value of the direct current grounding insulation impedance. The alternating current grounding insulation impedance is detected by using a necessary device, namely, the inverter in a photovoltaic power generation system. In this way, an additional detection device is not mounted, which reduces costs and complexity of alternating current grounding insulation impedance detection.

An apparatus provides precision measurement of voltage drop across a semiconductor switching element of a subsea device. The apparatus includes (a) a first circuit path having a first protective element, a first impedance element and a voltage source, wherein the first circuit path is configured to be connected between the first terminal and the second terminal of the semiconductor switching element, (b) a second circuit path formed between a first output terminal and a second output terminal, the second circuit path having a second protective element and a second impedance element, wherein the second protective element is identical to the first protective element, and wherein the second impedance element is identical to the first impedance element, and (c) a regulating circuit configured to regulating the current in the second circuit path such that said current in the second circuit path is equal to the current in the first circuit path, wherein the voltage drop between the first terminal and the second terminal of the semiconductor switching element equals the difference between the voltage provided by the voltage source and the voltage drop between the first output terminal and the second output terminal.

An electrical device having a clocked circuitry, and a method for testing the power supply unit of the electrical device. The electrical device comprises an electrical load, a clocked power supply unit, at least one pulse transformer and an evaluation device. The power supply unit comprises a power stack having at least one power semiconductor switch and is configured for generating a clocked voltage for the electrical load from an electric voltage based on an alternating on/off switching of the power semiconductor switch. The power stack exhibits at least one current path, through which an electric current flows during operation. The pulse transformer generates a signal assigned to the change in the charge and/or the direction of the electric current flowing through the current path. The evaluation device evaluates the signal coming from the pulse transformer and draws a conclusion regarding the operational reliability of the power semiconductor switch.