Embodiments of the present disclosure provide an insulation monitoring device applied to a power system and a power system. The power system includes at least one power electronic converter module. The insulation monitoring device includes an insulation component, a signal source, an impedance module, and a monitoring module. The insulation component at least partially wraps around the power electronic converter module. The signal source is electrically coupled to a circuit node in the power electronic converter module, the impedance module is connected between the signal source and the insulation component, and the monitoring module is configured to monitor an insulation resistance value of the insulation component, so that an insulation state of the power electronic converter module may be determined.

Methods and systems for detecting partial discharge in a stator for an electric motor are provided. An exemplary method includes applying a high voltage AC sinewave input signal to the stator and energizing at least one winding therein. The method includes sensing a first resulting load signal occurring in the stator with a first device and filtering the first resulting load signal to form a first high frequency signal indicating any partial discharge (PD) voltage occurring in the stator. The method also includes sensing a second resulting load signal occurring in the stator with a second device and filtering the second resulting load signal to form a second high frequency signal indicating any partial discharge voltage occurring in the stator. Further, the method includes processing the first and second high frequency signals to form a processed signal indicating whether partial discharge occurred.

An insulation inspection device includes: a conveyance unit that conveys a laminated electrode in which a first separator, a first electrode plate, a second separator, and a second electrode plate are laminated; a pressure roll that presses the laminated electrode against the conveyance unit; a first terminal electrically connected to the first electrode plate; a second terminal electrically connected to the second electrode plate, further electrically connected to the conveyance unit when the first separator is disposed on the conveyance unit side, and further electrically connected to the pressure roll when the first separator is disposed on the pressure roll side; and an insulation inspection unit that applies a voltage to the laminated electrode to inspect insulation condition of the laminated electrode.

The present invention provides a partial-discharge measurement method in which a partial-discharge defect signal and noise are separated, a partial-discharge defect position is detected, and the risk of a detected partial discharge defect is diagnosed. Further, this method provides a highly reliable high-voltage device. An electromagnetic wave generated by a sample is simultaneously measured by a plurality of sensors. A partial discharge and noise are separated through the comparison of the spatial intensity distribution of measured signals and a spatial signal intensity distribution measured beforehand at the time of the occurrence of a partial discharge, and a defect position is detected using a peak position. Further, the risk of a defective site is diagnosed on the basis of a simultaneously measured charge amount signal.

Eddy current inspection of the step iron region of a generator stator core lamina insulation is performed while the rotor is in situ, with inspection system (81). The system (81) excites the stator core (26) and then measures any eddy currents indicative of a damaged region. The inspection system carriage (42) and its pivoting extension arm (52) are inserted within the rotor gap (34) while the rotor (22) remains in situ within the generator (20). The EL CID system's eddy current sensing coil assembly (54) includes a Chattock coil (70), which is mounted in a coil housing (56, 58) that is in turn pivotally mounted on a distal end of the extension arm (52). A sensing surface (60) of the coil housing (56, 58) remains in abutting contact with the generator core circumference in the step iron region (32), despite the step-like profile of the core circumference in that region.

Described are system and method embodiments for shield fault detection to protect the cable, components and other circuits connected to the cable shield, and to avoid high short circuit currents flowing from a power source to ground during unexpected events. A threshold voltage detector and a slope detector may be used to sense the voltage on a shield pin switchably coupled to ground via a shield ground. Method embodiments to distinguish the shield ground switch current caused by a shield fault from normal operation are also discussed. In certain situations, a weak ground path is established first to sense or identify a valid attachment on the cable before establishing a strong ground path. The disclosed embodiments, separately or in combination, may effectively detect shield fault with improved performance.

An isolator includes: a transmission circuit that generates an alternating current transmission signal in which a first potential is set to be a reference potential; a first insulating element to which the alternating current transmission signal is supplied; a second insulating element that generates an alternating current reception signal in which a second potential is set to be a reference potential by being alternating current-coupled to the first insulating element through an insulating film; a reception circuit that reproduces reception data based on the alternating current reception signal; an impedance control unit that controls an impedance of the first or the second insulating element to be higher than an impedance before the control; and a leakage current detection unit that detects a leakage current flowing between the first and the second insulating elements through the first or the second insulating element in which the impedance has been controlled.

An apparatus for determining insulation resistance at a PV generator includes a first unit configured to shift a generator potential at an output terminal of the PV generator, and a second unit. The second unit is configured to determine the insulation resistance by: connecting a measurement voltage to the output terminal of the PV generator, measuring a first current value and a first voltage value at the output terminal of the PV generator before the measurement voltage is connected, measuring a second current value and a second voltage value at the output terminal of the PV generator after the measurement voltage is connected, and determining the insulation resistance of the PV generator based on the measured first and second current values and the measured first and second voltage values. The first and second units are connected in series.

Methods and systems for detecting partial discharge in a stator for an electric motor are provided. An exemplary method includes applying a high voltage AC sinewave input signal to the stator and energizing at least one winding therein. The method includes sensing a first resulting load signal occurring in the stator with a first device and filtering the first resulting load signal to form a first high frequency signal indicating any partial discharge (PD) voltage occurring in the stator. The method also includes sensing a second resulting load signal occurring in the stator with a second device and filtering the second resulting load signal to form a second high frequency signal indicating any partial discharge voltage occurring in the stator. Further, the method includes processing the first and second high frequency signals to form a processed signal indicating whether partial discharge occurred.

An oil resistance test method for an electronic device is provided. At least one type of resin material is provided on at least a portion of an outer surface of the electronic device. The oil resistance test method includes: setting a test temperature; and immersing the electronic device in a water-soluble cutting oil in an atmosphere of the set test temperature. This cutting oil contains a mineral oil and a surfactant, and exhibits a milky-white appearance when diluted with water. The oil resistance test method further includes: determining, based on an electrical characteristic of the electronic device, whether or not the electronic device has been degraded by the cutting oil; and estimating, based on a total immersion time of the electronic device in the cutting oil until degradation of the electronic device is detected, a life of oil resistance of the electronic device.