A switching device has a current transformer for measuring in a potential-free manner a current to be switched by the switching device, a current sense amplifier, to which the unrectified measurement current of the current transfer is fed on the input side, and a controller, to which the output current of the current sense amplifier is fed on the input side and which is configured so as to digitalize the fed output current and to perform one or more performance-related measurements and to output the measurement results.

A method is disclosed for testing a latching magnet of a switch including a switching contact, formed from contact elements mechanically separated from one another for opening the switching contact; an electronic trip unit, to monitor current flowing via the contact elements and to perform a test for a current-dependent trip condition; an electrical energy store, forming a circuit with the winding of the latching magnet, the circuit being closed for a first closing time when the trip condition of the trip unit is met; and an actuator, actuable by closing off the circuit and configured to separate the contact elements. For test purposes, the circuit is closed for a second closing time, which is so short that separation of the contact elements by the actuator does not take place. A test is then performed to ascertain whether there is a current flowing via the winding of the latching magnet.

A method is disclosed for testing a latching magnet of a switch including a switching contact, formed from contact elements mechanically separated from one another for opening the switching contact; an electronic trip unit, to monitor current flowing via the contact elements and to perform a test for a current-dependent trip condition; an electrical energy store, forming a circuit with the winding of the latching magnet, the circuit being closed for a first closing time when the trip condition of the trip unit is met; and an actuator, actuable by closing off the circuit and configured to separate the contact elements. For test purposes, the circuit is closed for a second closing time, which is so short that separation of the contact elements by the actuator does not take place. A test is then performed to ascertain whether there is a current flowing via the winding of the latching magnet.

The present invention provides a detecting method and a detecting apparatus for abnormal electrical connection in a main circuit of switchgear, wherein the detecting method comprises: acquiring a plurality of temperature rising values for measured areas of a plurality of electrical connectors in the main circuit of switchgear, the plurality of temperature rising values comprise a temperature rising value at a joint area of at least one of the electrical connectors; calculating a weighted average temperature of the plurality of temperature rising values; dividing each of the plurality of temperature rising values by the weighted average temperature to get normalized temperature rising values for the measured areas of the respective electrical connectors; comparing each of the normalized temperature rising values for the measured areas of the electrical connectors with a corresponding one of normalized threshold values for the measured areas of the respective electrical connectors. The detecting method of the present invention can accurately determine whether electrical connection of the measured areas of electrical connectors is abnormal under any electrical current.

A synthetic test circuit, for performing an electrical test on a device under test, is provided. The circuit includes a terminal connectable to the device under test; a voltage injection circuit-operably connected to the terminal, the voltage injection circuit including a voltage source, the voltage source including a chain-link converter, the chain-link converter including a plurality of modules, each module including a plurality of module switches connected with at least one energy storage device; and a controller-configured to operate each module of the voltage injection circuit to selectively bypass the or each corresponding energy storage device and insert the or each corresponding energy storage device into the chain-link converter so as to generate a voltage across the chain-link converter and thereby operate the voltage injection circuit to inject a unidirectional voltage waveform into the device under test.

A system and method are disclosed for monitoring at least one relay contact. The system may include an emitter adapted for communication with a relay contact and configured to emit a signal, and a receiver adapted for communication with the relay contact and configured to detect a signal emitted by the emitter. The system may further include a controller adapted for communication with the emitter and receiver, and configured to determine an open or closed state of the relay contact. The controller may control the emitter to emit a signal, may determine a closed state of the relay contact if the receiver detects the signal, and may determine an open state of the relay contact if the receiver fails to detect the signal.

Systems and methods to detect that a protective device is operating outside of a time inverse overcurrent tolerance region are described. For example, a central monitoring station may obtain a time inverse overcurrent tolerance region of a protective device on a power line. The central monitoring station may obtain a fault magnitude measurement and a fault duration measurement of a wireless line sensor on the power line. The central monitoring station may determine that the protective device is operating outside of the tolerance region based at least in part on the fault magnitude measurement and the fault duration measurement. The central monitoring station may provide a signal indicating that there is a potential issue with the protective device.

Provided is an assistance apparatus for localizing errors in a monitored technical system consisting of devices and/or transmission lines, including at least one processor configured to obtain values of actual attributes of the devices and/or of the transmission lines, determine an error probability for each device and/or transmission line by processing a graph neural network with the obtained actual values of attributes as input, wherein the graph neural network is trained by training attributes assigned to an attributed graph representation of the technical system, and output an indication for such devices and/or transmission lines, whose error probability is higher than a predefined threshold.

The present invention relates to a method and a monitoring system, for monitoring a vacuum on-load tap changer. The tap changer includes a housing with insulating fluid, a diverter switch inside of the housing and including at least one movable contact and at least two vacuum interrupters, and at least one pressure sensor which measures the pressure in the housing. The method, which is performed by a processing circuitry in the system, includes determining a pressure signature, including two succeeding peaks within a time interval, continuously measuring the pressure, detecting when the measured pressure shows the pressure signature, determining, based on the measured pressure within the pressure signature, the time between the first rise in pressure and the second drop, and setting the determined time to represent the switch time of the diverter switch.

The present invention relates to a method and a monitoring system, for monitoring a vacuum on-load tap changer. The tap changer includes a housing with insulating fluid, a diverter switch inside of the housing and including at least one movable contact and at least two vacuum interrupters, and at least one pressure sensor which measures the pressure in the housing. The method, which is performed by a processing circuitry in the system, includes determining a pressure signature, including two succeeding peaks within a time interval, continuously measuring the pressure, detecting when the measured pressure shows the pressure signature, determining, based on the measured pressure within the pressure signature, the time between the first rise in pressure and the second drop, and setting the determined time to represent the switch time of the diverter switch.