An input circuit for detecting low voltage analog signals in an electrically noisy environment receives the analog input signal at an input terminal. The analog input signal is compared to a variable reference signal at a comparator circuit. An active hysteresis circuit provides feedback to the comparator. In a first operating mode, the active hysteresis circuit may be disabled or be configured to output a constant voltage. In a second operating mode, the active hysteresis circuit may be enabled or configured to output a varying level of voltage. The output of the feedback circuit is summed with the variable reference signal and supplied as the input signal to the comparator, such that signal against which the analog input signal is compared is a general constant value in the first operating mode and varies with respect to time in the second operating mode.

An input circuit for detecting low voltage analog signals in an electrically noisy environment receives the analog input signal at an input terminal. The analog input signal is compared to a variable reference signal at a comparator circuit. An active hysteresis circuit provides feedback to the comparator. In a first operating mode, the active hysteresis circuit may be disabled or be configured to output a constant voltage. In a second operating mode, the active hysteresis circuit may be enabled or configured to output a varying level of voltage. The output of the feedback circuit is summed with the variable reference signal and supplied as the input signal to the comparator, such that signal against which the analog input signal is compared is a general constant value in the first operating mode and varies with respect to time in the second operating mode.

A circuit device can be implemented, which includes a zener diode barrier composed of one or more zener diodes. The circuit device further includes one or more detection circuits electronically in series with the zener diode (or zener diodes) of the zener diode barrier. The zener diode barrier functions as an IS (Intrinsically Safe) barrier. The detection circuit (or circuits) facilitates the production of detailed information concerning different types of events detected by the detection circuit(s).

A diagnostic system configured to detect a stator winding fault in an electrical machine comprising a plurality of stator windings is provided. The diagnostic system includes a processor programmed to receive measurements of three-phase voltages and currents provided to the electrical machine, compute positive, negative, and zero sequence components of voltage and current from the three-phase voltages and currents, and identify a noise factor contribution and a stator fault contribution to the negative sequence voltage by performing a two-step initialization algorithm comprising a modified recursive least square (RLS) method, the noise factor contribution comprising unbalance in the electrical machine resulting from one or more of positive sequence current, negative sequence current, and positive sequence voltage. The processor is still further programmed to detect a stator fault in the electrical machine based on the stator fault contribution to the negative sequence voltage.

Disclosed is a high accurate measurement circuit, and the feature is using bias switching circuit for compensating front end offset, and the back end offset of amplifier is also cancelled. In the real measurement environment, offset exists in the amplifier of the measurement circuit has, and non-ideal effects also exist in the interface between measurement terminal and the measurement circuit, such as leakage current of chip package pins or mismatch of the circuit. The above non-ideal effects belong to front end offset and cannot be compensated by the prior arts. The disclosed structure uses the bias switch circuit and uses different switching method in the two measurement timings. By subtracting the measurement results for the two measurement timings, the front end offset is compensated, and the back end offset of the amplifier is also cancelled.

A current sensor integrated circuit to sense a current through a resistor includes a substrate, a tub disposed in the substrate, an analog front end disposed in the tub and comprising an amplifier having inputs coupled across the resistor and a charging circuit configured to bias the analog front end and the tub to a bias voltage that is a predetermined offset voltage greater than a common mode voltage associated with the resistor. In embodiments, the analog front end is biased to a first bias voltage and the tub is biased to a second, different bias voltage.

The overcurrent protection device includes: a current detection unit configured to detect, as a sense voltage, a sense current flowing through a current sense terminal of a voltage-controlled semiconductor device; an overcurrent detection unit configured to compare the sense voltage detected by the current detection unit with an overcurrent threshold value to output an overcurrent detection signal; a mode determination unit configured to determine whether a superposition mode in which a transient sense voltage is superimposed on the sense voltage or a normal mode in which the transient sense voltage is not superimposed on the sense voltage; and a timing adjustment unit configured to adjust a detection start timing of the overcurrent detection signal based on a result of determination by the mode determination unit.

A correction control module for a power factor correction circuit comprises a current sampling unit, an adjustment unit and a control unit. The current sampling unit generates a sampling current based on the operation of a power factor correction circuit. The adjustment unit is connected to the current sampling unit and receives the sampling current. The adjustment unit is composed of a fixed resistance branch and a variable resistance branch connected in parallel with the fixed resistance branch, and the variable resistance and fixed resistance branches receive the sampling current to generate a node voltage. The control unit controls a resistance of the variable resistance branch based on an input voltage and an output voltage of the power factor correction circuit. Thus, an equivalent resistance of the variable resistance branch and the fixed resistance branch is changed according to an operating state of the power factor correction circuit.

A partial discharge (PD) detection system includes a PD sensor configured to sense a PD event of an electrical system and to generate a sensor signal in response to the PD event. An envelope generator is coupled to receive the sensor signal from the PD sensor. The envelope generator extracts an envelope signal from the sensor signal. A digitizer is configured to convert the envelope signal to a digital representation of the PD event.

Provided is a current measuring device for measuring current, including a conductor adapted to pass current therethrough, a circuit board with a wire, the wire being adapted to extract a voltage signal from the conductor, a cover member adapted to house the circuit board, first fixing means provided on the cover member, and second fixing means fixed in combination with the first fixing means, in which the conductor is mounted between the first fixing means and the second fixing means.