An example embodiment is a voice appliance including: a plurality of user interface devices comprising at least a microphone and a speaker; a plug for receiving power to the appliance or load; and a communication subsystem configured for wired communication with an electrical receptacle through the plug when plugged into the electrical receptacle. An electrical receptacle for connection to power lines comprises: at least one plug outlet configured to provide DC output, wherein the at least one plug outlet is configured to provide access to a wired communication network defined by at least one of the power lines. The plug outlet can be a Universal Serial Bus (USB) plug outlet to connect to a mobile device or are movable USB memory device. An intelligent junction box at the circuit breaker panel is configured to perform dynamic power allocation and power line communication.

A protector for an electricity supply circuit includes: a power switch for switching between connection and disconnection of the electricity supply circuit; a controller configured to output a switching command signal to the power switch in accordance with an input signal; and a current detector for detecting current flowing to the electricity supply circuit. The controller includes: a lower limit threshold determination unit configured to determine whether or not an estimated temperature of a power line has dropped below a lower limit threshold; a timer for counting the time that passes after a load has been turned off, when the load is turned off by the power switch; and a mode switching unit configured to switch the controller to a sleep mode when a predetermined time is counted by the timer and the lower limit threshold determination unit determines that the estimated temperature has dropped below the lower limit threshold.

A circuit body for a vehicle includes: a plurality of control boxes dispersedly arranged on the circuit body; a trunk harness connecting one of the control boxes to another of the control boxes; and a branch harness connecting the control boxes to the electric component. The control boxes, the trunk harness and the branch harness are configured to ground a power circuit and a signal circuit through grounding routes different from each other. The power circuit supplies the electric power from a power source to the electric component through the control boxes. The signal circuit transmits a communication signal between the control boxes and the electric component and between one of the control boxes and another of the control boxes.

A detection device for detecting a short circuit current in an electrical power transmission cable having an electrical power transmission cable for a high-voltage DC network. The network includes a central core, an insulating sheath, a metal screen arranged around the insulating sheath, at least one optical fibre, arranged between the electrically conductive central core and the metal screen by forming windings around the central core in a detection region, two optical transmitters arranged at the ends of the electrical power transmission cable, two optical detectors arranged at ends of the electrical power transmission cable, two interruption devices arranged at the ends of the electrical power transmission cable when a change in the angle of polarisation with respect to a reference angle greater than a predetermined value is detected by the first optical detector.

The invention relates to a charger, comprising an AC plug and a wire terminals, said AC plug being connected to a high voltage AC and supplying power to the device through a terminal, wherein said terminal is provided with a two-phase AC electrical wiring probe, a DC electrical connection probe and a data line probe; said AC wire probe is connected with a null wire or a live wire through a relay; said DC wire probe is connected with AC through a transformer; said terminal is further provided with a controller; said controller is connected with the sensor to control the connection and disconnection of the relay; the terminal of the electrical equipment is provided with the corresponding probe hole; AC is supplied for equipment while DC is for the internal control components; data line is used for the data communication transmission between electric equipment and the terminal.

A concomitant impedance protection method for a half-wavelength power transmission line includes that: three-phase currents and three-phase voltages of a relay protection device mounting position at an M side and a relay protection device mounting position at an N side of the half-wavelength power transmission line are acquired respectively; it is judged whether starting amounts of an M side and an N side meet starting conditions or not; a failure point F is determined according to a time difference when the starting amounts of the M side and the N side meet the starting conditions; and a relay protection action of the half-wavelength power transmission line is started according to concomitant impedance of the half-wavelength power transmission line. According to the method, a failure may be located by a time-difference method according to a characteristic of the failure, by compensating the voltages and currents on two sides of the line to construct concomitant impedance, and failures in the region of line can be correctly reflected. Since concomitant impedance protection effectively utilizes two-terminal electrical information, the fault can be quickly and reliably operated in the line region, misoperation on the failures out of the line region can be avoided, and the protection has relatively higher sensitivity.

There is provided mechanisms for differential protection of a transmission line (20) of a transmission system (25). A method comprises obtaining a restraining current and a differential current from the transmission line (S102). The method comprises determining a compensation current for the differential current (S104). The method comprises providing the differential current as compensated for by the compensation current and the restraining current to a differential protection arrangement for making a trip decision (S106). The method comprises detecting an internal fault for the transmission system (S108). The method comprises, as a result thereof, providing the differential current without being compensated for by the compensation current and the restraining current to the differential protection arrangement for making the trip decision (S110).

A line protection device includes terminals to connect the line protection device in series with an electric line. A current sensor of the line protection device senses a value of electric current through the electric line. A digital filter circuit of the line protection device performs digital filtering of the value of electric current. Depending on the digitally filtered value of the electric current, a switch control circuit of the line protection device controls a switch to interrupt flow of the electric current through the line.

Techniques for determining whether a downed conductor is present in an electrical power distribution network that includes a neutral line and a plurality of energized conductors are disclosed. For example, a sampled neutral current signal is received, the sampled current signal including a plurality of values, each of the values representing an amplitude of current that flows in of the neutral conductor at a particular time; an unfiltered current signal is generated based on the sampled current signal; the sampled current signal is filtered to generate a filtered current signal; the unfiltered current signal and the filtered current signal are compared to generate an error signal; and the error signal is analyzed to determine whether at least one of the plurality of conductors is a downed conductor.

A line protection device includes a current sensor, a digital filter circuit, a switch control circuit, and a non-volatile memory circuit. The current sensor is adapted to a sense a value of electric current through the electric line. The digital filter circuit is adapted to perform digital filtering of the value of electric current. The switch control circuit is adapted to control a switch to interrupt flow of the electric current through the electric line depending on the digitally filtered value of the electric current. The non-volatile memory circuit is adapted to store a state of the digital filter circuit.