A method for detecting fault direction of a transmission line of an AC power system and a control system using the same. The method includes sampling current values and voltage values at one end of the transmission line for a series of time points; computing instantaneous voltage values at compensated point on the transmission line from the current value samples and the voltage value samples based on a time domain lumped parameter differential equation for the transmission line for the series of time points; recording the current value samples and the computed instantaneous voltage values at the compensated point; computing at least one voltage fault component each using the recorded computed instantaneous voltage values for at least the at least two of the series of time points; identifying the fault direction in consideration of the at least one computed voltage fault component and the at least one computed current fault component; and generating a fault direction signal indicating the identified fault direction. Where a fault directional element is designed using the voltage fault components at the compensated point, it will work well for the AC power system with strong power source.

It is an object to provide a power conversion device and a ground fault location diagnosis method for determining ground fault locations on a motor and a cable and notifying a user or an external device or system of a determination result even when ground faults of a plurality of phases occur at locations close to each other. In order to achieve the above object, the power conversion device includes a ground fault current measurement unit, an interphase short-circuit current measurement unit, and a ground fault location determination unit. The ground fault current measurement unit turns on all the switches of either upper arms or lower arms of three half- bridge circuits, and measures output current values of a plurality of phases generated during the ON period. The interphase short-circuit current measurement unit turns on a switch of an upper arm of one phase of the three half-bridge circuits and a switch of a lower arm of a phase different from the one phase, and measures output current values of a plurality of phases generated during a period of time for which both the switches are ON. The ground fault location determination unit determines a ground fault location based on the output current values measured by the ground fault current measurement unit and the output current values measured by the interphase short-circuit current measurement unit.

A system includes a generator. Three AC feeders are connected for feeding AC output from the generator. A rectifier is electrically connected to the three AC feeders and to a load via a first DC feeder and a second DC feeder. A first resistor connects between a first one of the DC feeders and ground. A first voltage sensor is operatively connected to detect voltage across the first resistor. A second resistor connects between the second DC feeder and ground. A second voltage sensor is operatively connected to detect voltage across the second resistor. A controller is configured to monitor for changes in common mode voltage based on the input from the first sensor and from the second sensor, and to determine presence of a fault if change in the common mode voltage exceeds a predetermined threshold.

A hybrid vehicle includes a power bus electrically connected to an inverter and an electrical socket electrically connected to the power bus. A ground fault circuit interrupter (GFCI) is electrically connected between the power bus and the socket. The GFCI has a circuit breaker with a mechanical reset. An actuator arrangement is configured to actuate the mechanical reset to reset the circuit breaker.

A device for detecting an arc fault in a polyphase electrical installation comprises: a high-frequency measuring system coupled to at least two electrical phase lines of the installation, said measuring system being configured to extract a first signal representative of high-frequency components of electrical currents flowing through said phase lines; a plurality of low-frequency measuring systems, each coupled to one electrical phase line of the installation, each being configured to acquire a second signal representative of the alternating line current flowing through the corresponding phase line; and a data-processing module programmed to detect an arc fault on the basis of the second signals and of the first signal.

In an electrical distribution system including a solid-state circuit breaker (SSCB) and one or more downstream mechanical circuit breakers (CBs), a solid-state switching device in the SSCB is repeatedly switched ON and OFF during a short circuit event, to reduce a root-mean-square (RMS) value of the short circuit current. The resulting pulsed short circuit current is regulated in a hysteresis control loop, to limit the RMS to a value low enough to prevent the SSCB from tripping prematurely but high enough to allow one of the downstream mechanical CBs to trip and isolate the short circuit. Pulsing is allowed to continue for a maximum short circuit pulsing time. Only if none of the downstream mechanical CBs is able to trip to isolate the short circuit within the maximum short circuit pulsing time is the SSCB allowed to trip.

A method, control system and protective relay are provided for detecting faulted phases of transmission lines in an AC power system. The method includes sampling electric signals at one end of the transmission lines at a series of time points; computing instantaneous voltage values of electric signals at compensated points on the transmission lines from the values of the sampled electric signals based on a time domain lumped parameter differential equation for the transmission lines for the series of time points; recording the computed instantaneous voltage values of the electric signals; computing fault component or sudden-change of the instantaneous voltage values of the electrical signals; detecting the faulted phases or fault types by comparing the calculated fault component of the instantaneous voltage values at the preset compensated points; and generating signals indicating the faulted phases of fault types.

A transformer system including a transformer including a set of wye windings, a three-phase current transformer, a neutral-current transformer, and a controller. The three-phase current transformer outputs a first signal indicative of a three-phase current conducting through the set of wye windings and the three-phase current transformer. The neutral-current transformer couples the current flowing from the ground to the neutral node of the transformer, and outputs a second signal indicative of a neutral current conducting from the ground node to the neutral node of the transformer. The controller receives the first signal and the second signal, determines whether an external ground fault condition or an internal ground fault condition is present based on the three-phase current and the neutral current, and determines whether a wiring error is present for the three-phase current transformer or the neutral-current transformer based on the three-phase current and the neutral current.

A system for detecting miswiring in an AC power supply for an appliance may comprise a phase sensor sensing the phase difference between the first and a second hot line powering heavy electrical loads therebetween, and a control module coupling to the phase and voltage sensors. The control module may identify a fault condition and may disconnect different electrical loads from the power supply in the fault condition.

An insertion determination unit (16) for precisely calculating a ground insulation resistance component of a leakage current regardless of the presence or absence of an inverter determines whether an inverter (3) is inserted between a commercial power system (2) and a three-phase motor (5). A resistance component leakage current calculation unit (18) calculates a ground insulation resistance component of a leakage current on the basis of a calculation procedure corresponding to the result of the above determination.