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).

Provided is an apparatus and method for protecting against unsafe electric current conditions. A protections circuit may be used in a device, such as an electric grill, that has one or more electric loads, such as heating elements. The protection circuit may protect against various failure scenarios, including, without limitation, instances of ground fault, over current, driver failure, and failure of a microprocessor. In response to a failure, the protection circuit may trip a latch relay or disable a triac driver to stop current from flowing.

An electronic control unit having a self-diagnosis function is realized in which an operation processing section is capable of identifying not only the presence or absence of the occurrence of NG of disconnection, an earth fault, and a power fault, but also three states of NG, OK, and indetermination. Therefore, when a diagnosis opportunity is present, a mask signal maintains a state of Not Mask even if the mask signal is subsequently brought into a mask state. When an operation processing device requests a drive circuit for communication therewith, the mask signal is set to the state of Mask, and information stored in a register is cleared. Further, when the mask signal is in the state of Mask when the operation processing device performs communication with the drive circuit, the operation processing device is capable of identifying that an indeterminate state free of the opportunity of the diagnosis is present.

Provided is an apparatus and method for protecting against unsafe electric current conditions. A protections circuit may be used in a device, as an electric grill, that has one or more electric loads, such as heating elements. The protection circuit may protect against various failure scenarios, including, without limitation, instances of ground fault, over current, driver failure, and failure of a microprocessor. In response to a failure, the protection circuit may trip a latch relay or disable a triac driver to stop current from flowing.

Example embodiments of the invention perform updating of arc-fault detection protection software in a dual function/combination arc-fault circuit interrupter (DF/CAFI) device, without requiring any hardware changes to the device. Maintenance software running in a processor in the device synchronizes downloading the updated protection software as packets of modulated data from a host device, downloaded over an electric power line connected to the device. The modulated data on the power line is sensed by a current sensor of the device and is filtered, demodulated, and sampled by the device. The maintenance software then assembles packets of the demodulated and sampled data and loads them into memory in the device as the updated arc-fault detection protection software.

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.

Techniques are disclosed relating to electrical safety systems that may be useful, for example, in electromagnetic geophysical prospecting. Electromagnetic streamer systems often include a number of electrical loads in series that are powered by a constant-current power supply unit. Known techniques for detecting electrical faults have various drawbacks in such an arrangement. Embodiments of this disclosure may be used to mitigate some or all of such drawbacks.

A system is described herein, including an activation circuit configured to generate a signal indicative of an alarm condition. A residual current device trigger circuit is coupled to the activation circuit and a residual current device. The residual current device trigger circuit is configured to provide a simulated earth leakage current condition to trigger the residual current device on receiving the signal indicative of the alarm condition.

A fuse box that is designed to prevent damage caused by arc faults and electrical overcurrent. The apparatus is configured to function as a circuit breaker. The apparatus includes a housing, a circuit breaker, an optical sensor, and an electronic controller. The housing is an enclosure that isolates the circuit breaker from light and protects the components from physical damage. The circuit breaker opens the circuit between connected electrical systems when arc fault or an electrical overcurrent is detected. The optical sensor detects arc faults and relays notifications to the electronic controller. The electronic controller enables a user to set the thresholds for arc faults, currents, and voltages that cause the circuit breaker to open.

A single-phase-to-earth fault processing device for a neutral non-effectively grounded distribution network includes a split-phase arc quenching device connected between earth and a three-phase bus of the distribution network, and a controller with an input end connected with a single-phase-to-earth phase selection device of the distribution network. The split-phase arc quenching device includes a multiphase switching device which operates independently for each phase, and a fuse connected in series with the multiphase switching device. The controller is for controlling opening and closing of three single-phase switches in the multiphase switching device. A single-phase-to-earth fault processing method firstly controls the split-phase arc quenching device to preprocess the fault. If the fault still exists, through a ground resistor a zero-sequence current is generated on a fault line. After delaying to wait for a line to isolate a fault section, a ground connection of the neutral is cut to restore the distribution network.