Monitoring a brake that includes first and second braking surfaces and a magnetizing device that, in response to the electric current supplied to them, are arranged to generate a magnetic field that is arranged to move the braking surfaces from a closed state, in which the braking surfaces are connected to each other, to an open state, in which the braking surfaces are separated from each other. Determining the electric current of the brake as the braking surfaces begin to move from the closed state to the open state, determining the maximum electric current of the magnetizing device of the brake in the open state, determining the condition of the brake as a current ratio from the electric current measured as the braking surfaces start to move to the maximum electric current.

Provided is a leakage current value calculation device which precisely calculates a leakage current I.sub.0r which is a component caused by a ground insulation resistance value of an electric circuit, in the leakage current I.sub.0 flowing through the electric circuit. The leakage current calculation device 10 includes a current measurement means 11 which measures a leakage current flowing through an electric circuit A having a predetermined protective conductor, a voltage measurement means 12 which measures respective phase-to-E phase voltages which are voltages between phases of the power supply unit 1 of the electric circuit A and the E phase when the protective conductor is the E phase, a voltage value calculation means 131 which calculates a predetermined voltage value obtained by extracting a voltage component applied to the ground insulation resistor excluding a potential difference caused by a grounding resistor of the protective conductor, based on the respective phase-to-E phase voltages; and a current value calculation means 141 which extracts a component caused by the ground insulation resistance value, excluding a ground capacitance component, from the leakage current, based on the predetermined voltage value.

The present disclosure relates to high-voltage circuits. The teachings thereof may be embodied in a circuit apparatus for detecting a state of an interlock loop monitoring a high-voltage component. The apparatus may include a power connection to a voltage source; a ground connection; a positive connection to a line end of the electrical interlock loop; a negative connection to a second line end of the interlock loop; a measuring arrangement for a voltage potential at the negative connection when two mutually different currents flow from the power connection via the negative connection to the ground connection; and a detector arrangement comparing the two potential measurements at the two respective currents with two predefined potential reference values and ascertaining, based on the comparison results of the comparison unit, whether the negative connection is electrically short-circuited with the positive connection, the power connection, or the ground connection, or with none of these connections.

A system for detecting and controlling an abnormal state of an electrical signal, includes: an abnormality decision part determining whether or not an electrical signal detected from a power line is abnormal by using the electrical signal and generating a control signal for controlling ON/OFF of N switches included in a leakage breaker. The system for detecting and controlling the abnormal state of the electrical signal is capable of controlling an operation of the leakage breaker by using voltage and current signals detected from the power line through which commercial power is supplied and functioning as a black box when an accident occurs such as a fire, etc.

Certain embodiments may generally relate to a smart fault detection device for power grids, and a method of fault detection for power grids. A method may include receiving raw data samples of currents in grounding conductors and line conductors. The method may also include processing the raw data samples under at least one of a plurality of system operating modes. The method may also include monitoring normal operation and anticipating an impending fault while operating under at least one of the system operating modes. The method may further include extracting fault information based on the monitoring. The method may also include reporting the fault information to a supervisory control and data acquisition system human-machine interface. The method may further include anticipating faults based on an analysis of the raw data samples.

During measuring an insulation resistance for an inverter having at least one half-bridge including two active switching elements for driving an output current, and a DC link voltage, a center point of the half-bridge positioned between the switching elements is connected to a grounding point by closing a grounding switch, and the center point connected to the grounding point is connected, one after the other, to a first ungrounded terminal and a second ungrounded terminal of the DC link voltage of the inverter present at the half-bridge by means of the two active switching elements of the half-bridge to establish a connection between the first and second ungrounded terminals, respectively, and the grounding point. A current flowing via the connection to the grounding point is measured using a measuring device.

A device for monitoring a neutral grounding resistor (NGR), including first and second NGRs electrically connected in parallel, a rectifier circuit electrically connected in series with the second NGR and a voltage source and a logic resistor electrically connected in series with the second NGR. A logic circuit measures current passing through the logic resistor and determines the resistance of the first NGR based on the measured current and the resistance of the second NGR. As such, a failed-open or failed-short condition of the first NGR may be identified based at least in part on the determined resistance of the first NGR.

An insulation inspection device for motors includes an inverter for driving a motor, a partial discharge detecting unit for determining soundness of the motor, and a control circuit for controlling the inverter. The control circuit adjusts a switching interval of a voltage pulse of the inverter so as to be equal to a pulse round-trip propagation time between the inverter and the motor, thereby generating surge voltage higher than driving voltage for the motor, between the motor and ground, and adjusts a switching time for each phase of the inverter, thereby generating surge voltage higher than driving voltage for the motor, between phases, thus performing insulation inspection.

A monitoring system having a monitoring unit and a circuit element that are integrated in an enclosure for protecting connections between the monitoring unit and the circuit element. The monitoring unit monitors the circuit element via a first electrical quantity, and the monitoring unit has a control unit and a first circuit unit and a second circuit unit. The first current is essentially or precisely equal in amplitude to the first current, and the first current and the second current flow simultaneously in the two line sections. The first current direction is opposite to the second current direction, and the first circuit unit ascertains a first voltage drop at the first line section, and the second circuit unit ascertains a second voltage drop at the second line section. The control unit ascertains the first electrical quantity from the first voltage drop and the second voltage drop.

A self-test module of an electronic circuit breaker includes a power supply assembly with a rechargeable battery, a self-test enablement assembly, an induced power supply assembly, a boost power supply, and a micro control unit (MCU). The self-test enablement assembly is connected to the rechargeable battery and includes an enablement button, a capacitor and a first power chip connected in series. The induced power supply assembly includes a buck chip. The boost power supply includes a second power chip and a boost chip connected in series. The MCU includes a plurality of pins that are connected to the first and second power chips, the buck chip, and the boost chip. The self-test module has two working modes; the electronic circuit breaker may be provided with or without a load current. The MCU operates the self-test procedure, indicates the self-test status, and maintains the indication for a period of time.