An arc fault detection system with a built-in-test includes an arc fault detector having a load noise voltage input, a test current input and an arc fault detector output. The system includes a processing unit having a switch in electrical communication with the test current input and an input in electrical communication with the arc fault detector output. A method for testing an arc fault detection system includes generating a new bit with a processing unit and outputting the new bit to a switch operatively connected to the processing unit to at least one of turn the switch on or turn the switch off. The method includes reading a signal at an input of the processing unit.

An apparatus and method for diagnosing a failure of a switch unit included in a multi battery pack. The magnitude of a pack current flowing from each of battery packs connected in parallel to a load is measured, a battery pack whose pack current has a magnitude smaller than the average value by a threshold value or more is identified, and it is determined that an open failure occurs at the switch unit included in the identified battery pack, and the information of the battery pack including the switch unit at which the open failure occurs is output. The internal resistance of each battery pack may be statistically analyzed in order to more accurately diagnose the failure at the switch unit. Thus, an open failure of switch units included in battery packs connected in parallel may be easily and reliably diagnosed in a statistical viewpoint.

Various embodiments of the teachings herein include methods for determining the state of an electrical switchgear assembly. The method may include: measuring an electric current and a voltage dropped across the switchgear assembly; ascertaining a time interval of an arc occurring during a switching operation; comparing the ascertained time interval to a reference value specific to the switchgear assembly; measuring a voltage profile during the time interval; and comparing the voltage profile with a reference voltage profile. The time interval begins when the value of the measured voltage exceeds a first threshold value. The time interval ends when the value of the current intensity falls below a second threshold value.

A cut-off circuit diagnostic device includes a motor control module that controls a motor, and an external safety module that is detachably attached to the motor control module. The motor control module includes: a motor drive unit that has an inverter circuit for controlling a voltage applied to the motor by pulse width modulation control and a drive circuit for driving a power element of the inverter circuit; a cut-off circuit that cuts off power supply to the drive circuit; and a first cut-off circuit diagnostic unit that has a first diagnosis pulse generator for generating a first signal to control the cut-off by the cut-off circuit and that detects whether or not the power supply to the drive circuit is cut off according to the first signal. The external safety module includes a second cut-off circuit diagnostic unit that has a second diagnosis pulse generator for generating a second signal to control the cut-off by the cut-off circuit and that detects whether or not the power supply to the drive circuit is cut off according to the second signal. The motor control module further includes a function switching unit that supplies the second signal to the cut-off circuit when the external safety module is attached to the motor control module, and supplies the first signal to the cut-off circuit when the external safety module is not attached to the motor control module.

An insulation detection method includes closing a main positive relay and a main negative relay in a high voltage safety box of each electric cabinet in an energy storage system; controlling an insulation detection board to perform insulation detection at a main power management system, and to report an insulation detection result to a power conversion system; controlling, if the insulation detection result at the main power management system indicates no fault and no instruction of starting insulation detection at the power conversion system is received, the insulation detection board to continue performing the insulation detection; and instructing, if the insulation detection result at the main power management system indicates an insulation fault, a battery management system of each electric cabinet to control the main positive relay and the main negative relay in the high voltage safety box to turn off.

An apparatus includes: a high-voltage module including: a current interrupter; an actuation system coupled to the current interrupter; a sensor system; and a terminal configured to electrically connect to an external electrical device. The apparatus also includes: a user interface; and an electrically insulating assembly between the user interface and the high-voltage module. In operational use, the user interface is grounded and the high-voltage module is at a system voltage.

This application discloses an energy storage system and an insulation detection method therefor. The insulation detection method includes: closing a main positive relay and a main negative relay in a high voltage safety box of each electric cabinet in the energy storage system; controlling the insulation detection board to perform insulation detection, and to report an insulation detection result to a power conversion system; controlling, if the insulation detection result at the main power management system indicates no fault and no instruction of starting insulation detection at the power conversion system is received, the insulation detection board to continue performing the insulation detection; and instructing, if the insulation detection result at the main power management system indicates an insulation fault, a battery management system of each electric cabinet to control the main positive relay and the main negative relay in the high voltage safety box to turn off.

A method of remotely monitoring a status of a surge arrester disconnector includes providing a long-range wireless mesh communication system including a plurality of disconnectors organized in a plurality of clusters. Each cluster includes a plurality of disconnectors that are physically located within a same cluster area. At least one of the disconnectors in each cluster is coupled to a communication device of a predetermined communication range. The method includes transmitting, from a first cluster, a status signal indicative of a status of a first disconnector in the first cluster to a second cluster located within the predetermined communication range, and consecutively transmitting the status signal from the second cluster to a third cluster within the predetermined communication range, until reaching an end cluster. The method includes transmitting, from the end cluster, the status signal to a monitoring station, and monitoring the status of the first disconnector at the monitoring station based on a result of transmission of the status signal.

A sticking diagnosis apparatus for diagnosing a presence of sticking at a positive-electrode relay and at a negative-electrode relay, the sticking diagnosis apparatus including: an obtaining section that obtains, a first voltage value that is a voltage between a point downstream of the positive-electrode relay and a point upstream of the negative-electrode relay and a second voltage value that is a voltage of a diagnosis circuit provided in parallel to the negative-electrode relay; a determination section that when the first voltage value is greater than or equal to a first threshold, determines that the positive-electrode relay is in a state in which the positive-electrode relay remains in the closed state, and when the second voltage value is less than or equal to a second threshold, determines that the negative-electrode relay is in a state in which the negative-electrode relay remains in the closed state.

Methods for monitoring a circuit breaker include detecting at least one operation of a circuit breaker to obtain at least one vibration signal of the circuit breaker. Each vibration signal is represented as one-dimensional data of a vibration amplitude over time during the operation of the circuit breaker. The vibration signal is transformed to two-dimensional frequency-time data. The transformed frequency-time data is compared with benchmark data characterizing the at least one operation of the circuit breaker. A health condition is determined of the circuit breaker at least in part based on the comparison. Both the frequency component and the time component in the detected test vibration signals are considered in condition determination of the circuit breaker. The condition can be determined with high accuracy.