A system includes a dry contact with a first pair of switchable electrodes, a wet contact with a second pair of switchable electrodes, an arc suppressor, and a controller circuit operatively coupled to the arc suppressor and the first and second pairs of switchable electrodes. The controller circuit is configured to detect a failure of the wet contact and determine a stick duration associated with the first pair of switchable electrodes. The stick duration is based on a duration between an instance when a coil of the dry contact is deactivated and an instance of separation of the first pair of switchable electrodes during deactivation of the coil. The controller circuit generates, in-situ and in real-time, health assessment for the first pair of switchable electrodes based on a comparison of the determined stick duration with an average stick duration associated with a window of observation.

An arrangement for an overvoltage protection of a subsea electrical apparatus and a method for operating it. The arrangement includes a tank submersible below a water surface level, an electrical apparatus accommodated in the tank, and a surge arrester arrangement accommodated in the tank and coupled to a power supply of the electrical apparatus in the tank for providing the overvoltage protection of the electrical apparatus. The arrangement further includes a controllable grounding switch for connecting the surge arrester arrangement to a ground point in response to a control of the grounding switch to a closed state and for disconnecting the surge arrester arrangement from the ground point in response to a control of the grounding switch to an open state.

An arrangement for an overvoltage protection of a subsea electrical apparatus and a method for operating it. The arrangement includes a tank submersible below a water surface level, an electrical apparatus accommodated in the tank, and a surge arrester arrangement accommodated in the tank and coupled to a power supply of the electrical apparatus in the tank for providing the overvoltage protection of the electrical apparatus. The arrangement further includes a controllable grounding switch for connecting the surge arrester arrangement to a ground point in response to a control of the grounding switch to a closed state and for disconnecting the surge arrester arrangement from the ground point in response to a control of the grounding switch to an open state.

A method for monitoring a three-phase network that is operated in a compensated manner for a tuning change of the arc suppression coil. Reference network parameters and a reference network frequency are determined for a tuned state, and a current network frequency is determined for a current state. A reference characteristic variable, which is proportional to a displacement voltage, is determined for the current network frequency using the reference network parameters, and a current characteristic variable, which is proportional to a displacement voltage, is determined at the current network frequency. A differential variable is determined from the reference characteristic variable and the current characteristic variable, from which, with a predetermined threshold value being exceeded, a tuning change is identified and changed network parameters are determined.

A method for monitoring a three-phase network that is operated in a compensated manner for a tuning change of the arc suppression coil. Reference network parameters and a reference network frequency are determined for a tuned state, and a current network frequency is determined for a current state. A reference characteristic variable, which is proportional to a displacement voltage, is determined for the current network frequency using the reference network parameters, and a current characteristic variable, which is proportional to a displacement voltage, is determined at the current network frequency. A differential variable is determined from the reference characteristic variable and the current characteristic variable, from which, with a predetermined threshold value being exceeded, a tuning change is identified and changed network parameters are determined.

A fault protection arrangement may include a neutral grounding resistor, the neutral grounding resistor comprising a ground end and a non-ground end. The fault protection arrangement may include a neutral grounding resistance monitor assembly, coupled to the neutral grounding resistor, where the neutral grounding resistance monitor assembly includes a sense circuit, coupled to the ground end of the neutral grounding resistor; and an injection signal generator, arranged to generate a frequency of 240 Hz or greater.

A device includes an EMC (electromagnetic compatibility) filter, a frequency converter coupled to the EMC filter, and a motor coupled to the frequency converter via a motor cable. A leakage current compensator includes a leakage current detector and a compensation current generator configured to generate a compensation current that is directed against the leakage current and is overlaid on the leakage current in such a way that the leakage current is reduced.

The application relates to a transmission cable joint for a medium voltage underground cable system. The cable joint comprises at least a casing and connection terminals for coupling wires of transmission cables. In addition, the connection terminals are in connection with an inductance component that is sheltered by the casing and limits capacitive earth fault current, when the coupled cables produce such current.

The application relates to a transmission cable joint for a medium voltage underground cable system. The cable joint comprises at least a casing and connection terminals for coupling wires of transmission cables. In addition, the connection terminals are in connection with an inductance component that is sheltered by the casing and limits capacitive earth fault current, when the coupled cables produce such current.

A system and method for identifying an earth fault in a resonant grounded medium voltage network that employs a REFCL compensation system. The method derives a zero-sequence real power from a phase voltage to ground on each phase and a current on each phase and aligns the zero-sequence real power in time with a magnitude of a zero-sequence voltage provided by the REFCL compensation system. The method determines when the zero-sequence real power and the zero-sequence voltage exceed predetermined thresholds. The method delays the magnitude of the zero-sequence voltage for a predetermined period of time when the zero-sequence voltage exceeds the threshold and determines that the fault is occurring when both the time aligned zero-sequence real power exceeds the threshold and the magnitude of the zero-sequence voltage exceeds the threshold for the predetermined period of time at the same time.