An earth fault detection apparatus includes a switch group configured to switch between a first measurement path including a battery and a capacitor, a second measurement path including the battery, a negative-side insulation resistance, and the capacitor, a third measurement path including the battery, a positive-side insulation resistance, and the capacitor; and a control unit configured to calculate a reference value, based on each charging voltage of the capacitor in each measurement path, and configured to calculate an insulation resistance with reference to a predetermined conversion map, in which the conversion map includes a conversion map corresponding to a capacitance of the capacitor, and the control unit estimates the capacitance of the capacitor, and refers to the conversion map corresponding to the capacitance of the capacitor that has been estimated.

An earth fault detection apparatus includes a switch group configured to switch between a first measurement path including a battery and a capacitor, a second measurement path including the battery, a negative-side insulation resistance, and the capacitor, a third measurement path including the battery, a positive-side insulation resistance, and the capacitor; and a control unit configured to calculate a reference value, based on each charging voltage of the capacitor in each measurement path, and configured to calculate an insulation resistance with reference to a predetermined conversion map, in which the conversion map includes a conversion map corresponding to a capacitance of the capacitor, and the control unit estimates the capacitance of the capacitor, and refers to the conversion map corresponding to the capacitance of the capacitor that has been estimated.

A method for evaluating partial discharge signals. Partial discharge signals are captured, at only one point or at a plurality of points, near insulation of the electrical outer conductors of a multi-phase alternating current. The multi-phase alternating current, flowing in respective outer conductors, has fixed phase shifts relative to each other. Partial discharge signals are superposed on each other. At least one characteristic variable of the partial discharge signals is defined. Each partial discharge signal is assigned a phase position. A characteristic variable value of each characteristic variable is determined. Each partial discharge signal is assigned a number tuple from each characteristic variable value of the partial discharge signal and from the phase position. Clusters of the partial discharge signals in a multi-dimensional space with points formed by the number tuples are determined. A partial discharge activity is determined for each outer conductor from the determined clusters.

The invention relates to a method and a photovoltaic inverter (2) for determining the insulation resistance (R.sub.iso) of a photovoltaic system (1) relative to ground (PE). According to the invention, the voltage required for the measurement can be provided by the intermediate circuit (6) in the form of the intermediate circuit voltage (U.sub.Zk), and the measuring device (13) is designed to actuate an input short-circuit switch (S.sub.Boost) for short-circuiting the DC input (3) with the AC disconnector (8) open, as a result of which the intermediate circuit voltage (U.sub.Zk) can be applied to the DC input (3) in the reverse direction, and the measuring device (13) is configured to record measured voltages (U.sub.M1, U.sub.M2) with the switch (S.sub.iso) of the voltage divider (14) open and closed, and to determine the insulation resistance (R.sub.iso) from the measured values of the two measured voltages (U.sub.M1, U.sub.M2) recorded with the switch (S.sub.iso) of the voltage divider (14) open and closed.

An electric power conversion device has a function of detecting, at low cost and at an early stage, a sign of insulation failure of a transformer or a rotational machine. This electric power conversion device is provided with an inverter circuit and a PWM signal generation unit that makes a comparison between a carrier signal and a voltage command value and generates a PWM signal for driving the inverter circuit. The electric power conversion device feeds and receives electric power through connection to a transformer or a rotational machine provided with a winding wire. The electric power conversion device is provided with: a current sensor that detects a current to be fed to or received from the transformer or the rotational machine; and a diagnostic unit that diagnoses insulation degradation of the transformer or the rotational machine.

A controller (1) forms an insulation measurement path and turns on a third switch connected in parallel to a capacitor, (2) after a lapse of a first time period turns off the third switch, and (3) detects an insulation abnormality based on a voltage of the capacitor measured after a lapse of a second time period after the turning off of the third switch.

A system may include a transformer that may convert a first voltage to a second voltage, such that the second voltage is output via a conductor. The system may also include a wireless current sensor that may detect current data associated with current conducting via the conductor and a processor. The processor may receive the current data, determine one or more temperature measurements associated with the transformer based on the current data, and send a signal to a component in response to the one or more temperature measurements exceeding one or more respective threshold values.

In aspects of the present disclosure, a circuit interrupter includes a housing, a conductive path, a switch which selectively interrupts the conductive path, sensor(s), memory, and a controller within the housing. The sensor(s) measure electrical characteristic(s) of the conductive path. The memory stores an arc detection program that implements a machine learning model and includes a field-updatable program portion and a non-field-updatable program portion, where the field-updatable program portion includes program parameters used by the non-field-updatable program portion to decide between presence or absence of an arc fault. The controller executes the arc detection program to compute input data for the machine learning model based on the sensor measurements, decide between presence of an arc event or absence of an arc event based on the input data, and cause the switch to interrupt the conductive path when the decision indicates presence of an arc event.

A discharge detection system of the present invention includes a current detection section configured to detect a value of current flowing in a circuit; a high pass filter configured to detect noise in a high frequency band superimposed on the circuit by a discharge phenomenon; and a determination section electrically connected to the current detection section and the high pass filter. The determination section executes steps including determining whether the discharge phenomenon has occurred based on the noise in the high frequency band detected by the high pass filter, when the discharge phenomenon is determined to have occurred, calculating an increase or decrease in the current value at the occurrence of the discharge phenomenon based on the current value detected by the current detection section, and specifying information on the discharge phenomenon based on the increase or decrease in the current value.

A system to enable identification of arcing hazards comprises a data storage to store a set of measurements acquired by measurement units of a power distribution system. The system further comprises at least one processor configured to identify candidate arcing events represented by the measurements by using an unsupervised machine learning process, and to train a supervised machine learning classifier for automatic real-time identification of arcing events, by using labeled training data based on the identified candidate arcing events.