Passive monitoring the integrity of current sensing devices and associated circuitry in GFCI and AFCI protective devices is provided. A protection circuit interrupter employs a capacitively coupled noise signal obtained by an arrangement of one or both of line side arms relative to a Rogowski coil. The noise signal is monitored while the line and load sides of a protective circuit interrupter are disconnected, and the connection of the line and load sides disabled if the noise signal fails to correlate sufficiently to a reference noise cycle. When the line and load sides are connected, the RMS value of the observed current signal is monitored such that the line and load sides are disconnected if the observed current signal fails to meet an RMS threshold. The observed current signal is compensated by subtracting the reference noise cycle prior to monitoring for the fault condition applicable to the protective device.

Provided are a data alignment method, a differential protector, and a differential protection system. The data alignment method comprises: obtaining first sampled current data from a first sampling device; receiving a second message from a second differential protector, the second message comprising second sampled current data and its sampling time stamp, first time information of the second differential protector related to a difference in time of reception from receipt of the first message to a second time node, and second time information of the second differential protector related to a second transmission processing delay from the second time node to transmission of the second message; when time synchronization is maintained, calculating and storing a time calculation deviation between a third time node and a first calculated value of the second time node; when time synchronization is lost, determining the third time node according to the stored time calculation deviation.

Provided are a data alignment method, a differential protector, and a differential protection system. The data alignment method comprises: obtaining first sampled current data from a first sampling device; receiving a second message from a second differential protector, the second message comprising second sampled current data and its sampling time stamp, first time information of the second differential protector related to a difference in time of reception from receipt of the first message to a second time node, and second time information of the second differential protector related to a second transmission processing delay from the second time node to transmission of the second message; when time synchronization is maintained, calculating and storing a time calculation deviation between a third time node and a first calculated value of the second time node; when time synchronization is lost, determining the third time node according to the stored time calculation deviation.

A system and method is presented for lowering inrush current to an uninterruptible power supply. During a startup phase, an AC voltage is applied to the secondary winding of a transformer interposed between an input power supply and a rectifier. An active rectifier coupled to the secondary winding of the transformer is operated as an inverter and supplies the voltage to the secondary winding of the transformer during the startup phase. The magnitude of the AC voltage applied to the secondary winding of the transformer is initially less than the magnitude of the input voltage and is increased gradually over time until it reaches the magnitude of the AC input voltage. In this way, the magnetizing flux of the transformer is increased from zero to a steady-state without having the transformer saturate.

Apparatuses and methods for passively monitoring the integrity of current sensing devices and associated circuitry in protective devices such as Ground Fault Circuit Interrupters and Arc Fault Circuit Interrupters are provided. A protection circuit interrupter employs a capacitively coupled noise signal obtained by an arrangement of one or both of the line side arms relative to a Rogowski coil. The noise signal is monitored while the line and load sides of a protective circuit interrupter are disconnected, and the connection of the line and load sides disabled if the noise signal fails to correlate sufficiently to a reference noise cycle. When the line and load sides are connected, the RMS value of the observed current signal is monitored such that the line and load sides are disconnected if the observed current signal fails to meet an RMS threshold. The observed current signal is otherwise compensated by subtracting the reference noise cycle prior to monitoring for the fault condition applicable to the protective device.

Apparatuses and methods for passively monitoring the integrity of current sensing devices and associated circuitry in protective devices such as Ground Fault Circuit Interrupters and Arc Fault Circuit Interrupters are provided. A protection circuit interrupter employs a capacitively coupled noise signal obtained by an arrangement of one or both of the line side arms relative to a Rogowski coil. The noise signal is monitored while the line and load sides of a protective circuit interrupter are disconnected, and the connection of the line and load sides disabled if the noise signal fails to correlate sufficiently to a reference noise cycle. When the line and load sides are connected, the RMS value of the observed current signal is monitored such that the line and load sides are disconnected if the observed current signal fails to meet an RMS threshold. The observed current signal is otherwise compensated by subtracting the reference noise cycle prior to monitoring for the fault condition applicable to the protective device.

A DC protection scheme for protecting a DC power transmission medium within a DC electrical power network. The scheme includes a protection device coupled to a DC power transmission medium, being operable to protect the power transmission medium from a fault; an apparatus to measure at least one electrical property of the power transmission medium; and a controller programmed to determine the direction of the electrical fault; determine whether the electrical fault is an internal or external fault; and operate the protection device to protect the DC power transmission medium if the determination of the direction of the electrical fault and/or the determination of whether the electrical fault is an internal or external fault meet a predefined criterion.

A DC distance protection scheme for protecting a DC power transmission medium within the DC electrical power network. The DC distance protection scheme includes a protection device that is coupled in use to a DC power transmission medium. The protection device is operable to protect the DC power transmission medium from an electrical fault. The DC distance protection scheme also includes a measurement apparatus to selectively measure the current and voltage of the DC power transmission medium. In addition the DC distance protection scheme also includes a controller that is programmed to calculate an operating voltage of the DC power transmission medium using the measured current and voltage; perform a transient comparison between the calculated operating voltage and the measured voltage; and operate the protection device to protect the DC power transmission medium if the transient comparison meets a predefined criterion.

An electronic protection device (1) for a LV electric line (100) including one or more conductors (P, N), comprising: one or more pairs of electric contacts (10) adapted to be electrically connected with corresponding conductors of said electric line, said electric contacts being operatively coupleable or decoupleable one from another; a control unit (2) adapted to control the operation of said electronic protection device;

Said control unit comprises an electronic arrangement to detect and determine arc fault conditions in said electric line.

An electronic protection device (1) for a LV electric line (100) including one or more conductors (P, N), comprising: one or more pairs of electric contacts (10) adapted to be electrically connected with corresponding conductors of said electric line, said electric contacts being operatively coupleable or decoupleable one from another; a control unit (2) adapted to control the operation of said electronic protection device;

Said control unit comprises an electronic arrangement to detect and determine arc fault conditions in said electric line.