Devices herein may include conductor lines connected between a power supply and load, each of the conductor lines coupled to an AC contactor and a contactor control circuit, wherein the contactor control circuit is operable to open and close one or more contactors of the AC contactor. The devices may further include a current transformer coupled to the conductor lines, the current transformer operable to output a secondary current corresponding to a primary current magnitude of an electrical current not flowing to the load, wherein the AC contactor is connected between the power supply and the load. Devices may further include a zero cross detection circuit operable to generate an interrupt at each of a plurality of zero crossings for a microprocessor, and determine whether to open the one or more contactors of the AC contactor in a predetermined optimum interval calculated with respect to the zero crossing points.

Devices herein may include conductor lines connected between a power supply and load, each of the conductor lines coupled to an AC contactor and a contactor control circuit, wherein the contactor control circuit is operable to open and close one or more contactors of the AC contactor. The devices may further include a current transformer coupled to the conductor lines, the current transformer operable to output a secondary current corresponding to a primary current magnitude of an electrical current not flowing to the load, wherein the AC contactor is connected between the power supply and the load. Devices may further include a zero cross detection circuit operable to generate an interrupt at each of a plurality of zero crossings for a microprocessor, and determine whether to open the one or more contactors of the AC contactor in a predetermined optimum interval calculated with respect to the zero crossing points.

Various implementations are directed to a method for detecting, by a device, an increase in temperature at certain parts of an electrical system, and taking appropriate responsive action. The method may include measuring temperatures at certain locations within the system and estimating temperatures at other locations based on the measurements. Some embodiments include an integrated cable combining electrical conduction and heat-detection capabilities, or an integrated cable or connector combining electrical conduction with a thermal fuse.

A circuit interrupting device including a phase conductor, a neutral conductor, an interrupter configured to disconnect the phase conductor and the neutral conductor from a load, and a sensor configured to generate a signal indicative of current flowing through the phase conductor and the neutral conductor. The circuit interrupting device further includes a microcontroller that includes an electronic processor and is electrically connected to the first sensor and the interrupter. The microcontroller is configured to generate a reference signal, receive a first signal from the sensor, determine whether a difference between a voltage of the first signal and a voltage of the reference signal exceeds a threshold, determine whether the microcontroller has performed a ground fault self-test, and activate the interrupter when the difference exceeds the threshold and the microcontroller has not performed the ground fault self-test.

A wiring device including an interrupting device and a controller. The interrupting device electrically connects one or more line terminals to one or more load terminals when the interrupting device is in a reset condition and disconnects the line terminals from the load terminals when the interrupting device is in a tripped condition. The controller is configured to, determine a frequency of an input voltage at the one or more line terminals, determine whether the frequency is within a predetermined range, and when the frequency is within the predetermined range, perform a test of the wiring device.

A safety shut-off system and method are provided for eliminating power to a load in the event of smoke detection. The system may comprise a device located at the appliance for detecting a signal from a smoke detector, and cutting power to the appliance only when the appliance is in use. The device may be synchronized with any standard smoke alarm signal to reduce the number of false positive shut-offs. The system may also comprise a smoke alarm hard-wired to a circuit breaker, for shutting off power to all appliances on a particular breaker upon receipt of a signal from the smoke alarm, and only when the appliances on the breaker are in use. The system may also have the ability to shut off one breaker, multiple breakers, or all breakers at different time increments to actively prevent and reduce the damages caused by fires.

Various implementations described herein are directed to a method for detecting, by a device, an increase in temperature at certain parts of an electrical system, and taking appropriate responsive action. The method may include measuring temperatures at certain locations within the system and estimating temperatures at other locations based on the measurements. Some embodiments disclosed herein include an integrated cable combining electrical conduction and heat-detection capabilities, or an integrated cable or connector combining electrical conduction with a thermal fuse.

A residual current device (RCD) comprises test circuitry which issues intermittent first test pulses each simulating a residual current fault for which a corresponding fault signal is generated. In the case of a fault in which a corresponding fault signal is not received in respect of a first pulse, the RCD attempts to force the load contacts open. The test circuitry further issues intermittent second test pulses at a frequency less than that of the first test pulses, each second test pulse simulating a residual current for which a corresponding fault signal is generated. The duration of each corresponding fault signal is greater than the response time of the load contacts to allow the load contacts to open. If the test circuitry detects that the load contacts do not open, the RCD attempts to force the load contacts open.

The electric leakage protection device (feed control device includes an electric leakage detector, an electric leakage protector, and a self leakage generator. The electric leakage detector outputs an electric leakage detection signal when a current leaked from a main circuit exceeds a threshold value. The electric leakage protector opens a contact device interposed in the main circuit when receiving the electric leakage detection signal. The self leakage generator includes; a first short circuit having a first electric resistance component and a first switch component electrically connected in series with each other, and a second short circuit having a second electric resistance component and a second switch component electrically connected in series with each other. The first short circuit and the second short circuit are electrically connected in parallel with each other with regard to a pair of power supply paths constituting the main circuit.

The invention relates to a method for detecting a direct-current fault current in an electrical alternating-current circuit, wherein a rectifier unit (14) is connected to an alternating-current network (34) by means of a primary side (13) and provides a direct current on a secondary side (15) and wherein the alternating-current network (34) is protected by means of a fault-current circuit breaker (38), which interrupts the circuit if an alternating-current fault current greater than a specified alternating-current tripping threshold occurs. A direct-current fault current on the primary side (13) is measured and is compared with a specified direct-current tripping threshold. An alternating-current fault current is produced if the direct-current fault current lies above the tripping threshold. The invention further relates to a device (10) for detecting a direct-current fault current and to a charging apparatus (12) comprising such a device (10).