An object of the present invention is to propose a partial discharge determination device and method that can highly reliably determine the degree of progress of partial discharge occurring in an underground power transmission cable without preparing plural standard patterns. A distribution pattern of a set of the charge amount and the occurrence phase angle of each partial discharge occurring in a period of one or more cycles of an applied voltage of a power transmission cable is sequentially generated, a first classification process in which the pattern is classified into any one of classes on the basis of a standard distribution pattern for each class and a second classification process in which the distribution pattern are executed, a classification result by the first classification process is evaluated on the basis of a classification result by the second classification process, and the degree of progress is determined.

Provided are an electrical tree test device for a silicone rubber material for a cable accessory and a method for preparing a sample. The method includes: adding a semi-conductive silicone rubber into xylene, performing spraying on a surface of a silicone rubber insulation sample sheet, performing a curing processing, cutting the sample sheet into a high-voltage electrode with a triangular longitudinal section end, then adhering the high-voltage electrode on the surface of the silicone rubber insulation sample sheet, and performing a high temperature vulcanization to obtain a silicon rubber sample sheet; placing the silicon rubber sample sheet into a mold, injecting a high temperature vulcanizable liquid silicone rubber mixture, and performing the high temperature vulcanization, to obtain a sample; and performing cutting at a position distanced from a tip of the high-voltage electrode by 2 mm, and adhering a ground electrode of a flat plate-like structure at the cross section/

The invention relates to a member (O1) for measuring a variable representative of a common mode voltage (Vres) in an electrical network (1) or in a device (E), the network (1) or the device (E) comprising at least a first power conductor (C1) and a second power conductor (C2), the measuring member (O1) comprising two capacitive elements (EC1, EC2) which are intended to be arranged in a bridge between the two power conductors (C1, C2) and have capacity values that are identical to each other, wherein the two capacitive elements (EC1, EC2) are connected at a midpoint (M). The measuring member (O1) also comprises a two-terminal measurement circuit (SH) connected on the one hand to the midpoint (M) and on the other hand to a connection terminal intended to be electrically connected to a common conductor (Cc) provided in the electrical network (1) or the device (E).

The invention relates to a method, electrical circuit arrangements and insulation monitoring devices for an interference-resistant insulation monitoring of an ungrounded power supply system having a converter. Switching-frequent interfering signals, which are caused by operating the converter, are identified and assessed in a measured displacement voltage independently of the detection of a measuring signal in order to derive a switching (off) signal if required. Complementary thereto, an interfering resistance with respect to low-frequency interfering portions generated by the converter is attained by these low-frequency interfering portions being generated from a replica of a pulse width modulation signal of the converter and being suppressed sufficiently via subtraction that a monitoring without gaps (frequency) of the insulation resistance becomes possible.

A partial discharge (PD) detection system includes a node including a sensor configured to capacitively couple to a shield layer of a cable of an electric power line. The sensor is configured to collect, from the cable, sensor data indicative of an alternating-current (AC) electrical signal in the cable. The system further includes a high-pass filter configured to filter out low-frequency signals from the sensor data, and processing circuitry configured to detect, based on the filtered sensor data, a PD event at a location on the cable that is local to the sensor.

A fault monitoring device may monitor and detect for faults corresponding to a high-side voltage rail, to low-side voltage rail, or internally within a voltage source connected to the high-side voltage rail and the low-side voltage rail. The fault monitoring device may determine sample voltage levels and/or sample resistance values to detect the faults. Also, in various embodiments, the fault monitoring device may perform one or more fault monitoring processes over multiple stages. The fault monitoring device may determine the sample voltage levels and/or the sample resistance values while switching a secondary resistance circuit in different states over the multiple stages.

A fault monitoring device may monitor and detect for faults corresponding to a high-side voltage rail, to low-side voltage rail, or internally within a voltage source connected to the high-side voltage rail and the low-side voltage rail. The fault monitoring device may determine sample voltage levels and/or sample resistance values to detect the faults. Also, in various embodiments, the fault monitoring device may perform one or more fault monitoring processes over multiple stages. The fault monitoring device may determine the sample voltage levels and/or the sample resistance values while switching a secondary resistance circuit in different states over the multiple stages.

A diagnostic device includes electrical connectors, load, power supply, switching circuitry, sensors, and processor. The connectors include first and second sets of terminals for connecting to the conductors of a branch circuit in an upstream and downstream direction, respectively, at an outlet location along the circuit. The switching circuitry can isolate the upstream and downstream sections of the circuit from the outlet location, and selectively connect or disconnect the power supply or the load to the upstream or downstream section. The sensors measure electrical characteristics on the conductors of the circuit to monitor load currents, such as on power, neutral and ground lines, of the upstream and downstream circuit sections. The processor controls the switching circuitry, and obtains diagnostic information corresponding to the monitored load currents on the upstream and downstream sections of the branch circuit, from the measurements performed by the sensors.

A method for monitoring insulation in a motor drive circuit configured to convert DC power from a power source to AC power to drive a motor. The method includes boosting a DC link voltage of an inverter of the motor drive, isolating the motor drive circuit from the power source; performing at least one isolation test by providing a current path through components of the motor drive and preferably a motor connected to the output of the inverter to be tested; and monitoring the current during each isolation test to detect partial discharge or excessive leakage from the current path, thereby indicating that there exists defects in the insulation in the current path.

Disclosed is a device for checking withstand voltage of a connector-coupled cable. The device comprises: a pair of electrode boxes; and a control block configured to apply a start signal to a test instrument, which outputs a preset high voltage, according to an electrical state detected in each electrode box that includes: a housing whose a part of a front side is open; a conductive electrode plate mounted on an inner front side of the housing in such a way that it is rotatable around its top end; and a detection unit, mounted inside the housing with a predetermined gap from the electrode plate, to detect whether the electrode plate is rotated due to push on a lower part of the electrode plate. The electrical state is an electrical state between both terminals of the detection unit, and the preset high voltage is applied between both electrode plates.