Embodiments of the disclosure relate to detecting turn-to-turn faults in one or more windings of various objects. In one implementation, a fault detector receives a set of current measurements associated with a transformer and uses these measurements to execute a procedure for detecting a turn-to-turn fault in the transformer. The procedure can include dividing a steady-state differential current value by a steady-state voltage value to obtain one or more compensating factors, determining a magnetizing current amplitude indicator by multiplying the steady-state voltage value by the one or more compensating factors, determining a compensated differential current value by combining the steady-state differential current value with a modifier value that incorporates the magnetizing current amplitude indicator, comparing the compensated differential current value against a threshold value, and declaring an occurrence of the turn-to-turn fault in the transformer when the compensated differential current value exceeds the threshold value.

A power distribution monitoring system is provided that can include a number of features. The system can include a plurality of monitoring devices configured to attach to individual conductors on a power grid distribution network. In some embodiments, a monitoring device is disposed on each conductor of a three-phase network and utilizes a split-core transformer to harvest energy from the conductors. The monitoring devices can be configured to harvest energy from the AC power grid and saturate the magnetic core of the transformer in the event of a fault condition or when harvested power is not needed. Methods of installing and using the monitoring devices are also provided.

A relay protection method against LC parallel circuit detuning faults comprises the steps of: a relay protection device samples a current of a parallel LC, that is, a reactor and a capacitor, and samples a total current flowing through the whole LC; convert the current of the reactor into a current of an equivalent capacitor; calculate amplitudes of the current of the equivalent capacitor and a current of a realistic capacitor and calculate an amplitude of the total current flowing through the LC; calculate a current amplitude ratio of the equivalent capacitor to the realistic capacitor; and when the amplitude of the total current flowing through the LC is large enough, send an alarm signal or a trip after a setting time delay if the current ratio exceeds a preset upper and lower limit range. Also provided is a corresponding relay protection device.

The invention relates to a docking module (22) for a current transformer (10) comprising:

an electronic circuit (12) and

at least one electric connecting element (28.3) for electrically coupling the circuit (12) to the current transformer (10) and for docking the docking module (22) onto the current transformer (10).

A testing device tests an intelligent electronic device of a power system. A PC generates failure data by performing: simulation calculation for a CT and a PT with respect to current waveform data of a current transformer and voltage waveform data of a potential transformer based on a characteristic of an instrument transformer; and simulation calculation for an MU with respect to the current waveform data of the current transformer and the voltage waveform data of the potential transformer based on a characteristic of the MU. The testing device acquires device information data indicating a circuit breaker of the power system, in synchronization with the failure data. The testing device transmits the failure data and the device information data to the intelligent electronic device via a process bus in accordance with a setting of outputting data to the process bus and a setting of sampling.

A method for detecting an open current transformer in an electrical power system includes measuring for a voltage value on a secondary side of a current transformer. The method continues with observing the voltage value for a predetermined waveform and initiating corrective action in the electrical power system upon detection of the predetermined waveform.

A system for high-impedance differential protection for power systems using a variety of signals from the power system. A fault may be detected using filtered phase current or filtered phase voltage magnitudes from current transformers (CTs) connected in parallel by phase. A fault may be detected using filtered phase voltages and raw phase voltages from the CTs. A fault may be detected using raw phase currents and raw phase voltages from the CTs. A fault may be detected using filtered phase currents and raw phase currents. A fault may be detected using raw phase currents and raw neutral currents. The embodiments herein maintain dependability and security of a differential element even when low-class CTs are used. The embodiments herein may allow users to optimize pickup settings even when low-class CTs are used.

A method for detecting a fault, in particular an interruption, in a secondary circuit of a current transformer having a primary conductor formed by a part of a high-voltage conductor, includes inferring a fault in the secondary circuit if the magnitude of the mean current value relative to a time included within a selection time interval is less than a current value threshold. The selection time interval is determined based on a current value change variable and a current value change threshold. The current value change variable is formed based on at least two current values, assigned to different time points, of an electrical current flowing in the secondary circuit. A device for fault detection and a method and a system for monitoring and/or performing a protection function, for a current transformer, are also provided.