The disclosure provides an Internet of things device and a battery power supply circuit thereof. A voltage of a battery is compared with a predetermined over-discharge voltage to generate a comparison signal. A battery protection circuit serves as a power supply path from the battery to a load and determines whether to cut off the power supply path according to the comparison signal. The battery protection circuit cuts off the power supply path when the voltage of the battery decreases from a value greater than the predetermined over-discharge voltage to a value less than the predetermined over-discharge voltage, but does not turn on the power supply path when the voltage of the battery increases from a value less than the predetermined over-discharge voltage to a value greater than the predetermined over-discharge voltage.

A ground fault sensing circuit system includes a current transformer having a first winding and a second winding on opposite halves of the current transformer, outputting first and second signals, each winding coupled to a processor that determines information about respective currents in conductors monitored by the current transformer, based on a combination of the first and second signals. In another embodiment, the current transformer has a third winding wrapped continuously around both halves of the current transformer, overlapped with the first and second windings, the third winding outputting a third signal coupled to the processor, which determines information about respective currents in conductors monitored by the current transformer, based on a combination of the first, second, and third signals.

A cable with a signal detection function includes an insulating core, a second insulating layer, and a signal detection layer. The signal detection layer is for transmitting signal data. The cable further includes a second insulating layer, and plural signal detection layers provided for transmitting signal data. The signal detection layer and the insulating cores are disposed inside the second insulating layer, and the signal detection layer is cladded with plural insulating cores. If the first insulating layer in the signal detection layer is damaged, the signal detection layer will be electrically connected to the conductor assembly. The cable with the signal detection function can detect the abnormality of the insulating core through the signal detection layer to facilitate maintaining and repair the cable.

A power tool including a housing, a motor having a rotor and a stator, at least one grip sensor configured to generate a grip parameter, and a switching network electrically coupled to the brushless DC motor. An electronic processor is connected to the switching network and the at least one grip sensor and configured to implement kickback control of the power tool. The electronic processor is configured to determine a kickback threshold based on the grip parameter, control the switching network to drive the motor, receive a signal related to a power tool characteristic, determine, based on the power tool characteristic being greater than or equal to the kickback threshold, that a kickback event of the power tool is occurring, and control, in response to determining that the kickback event is occurring, the switching network to cease driving of the motor.

A system and method for protection of an electrical grid. A respective one of the substations of the system including: a first directional protective relay to generate a signal operating on the electrical power line between the respective one of the substations and a remote one of the substations; a cyber health module to receive remote signals from two remote directional protective relays and output a reliability signal based on consistency of the remote signals and a status of the communication channels being operational; a circuit breaker to interrupt electrical power flow when directed; and a comparison circuit to receive signals and to direct the circuit breaker to interrupt electrical power flow when the reliability signal from the cyber health module indicates consistency, the first directional protective relay indicates fault, and at least one of the remote directional protective relays indicate fault.

Circuits integrated or integrable with a photovoltaic panel to provide built-in functionality to the photovoltaic panel including safety features such as arc detection and elimination, ground fault detection and elimination, reverse current protection, monitoring of the performance of the photovoltaic panel, transmission of the monitored parameters and theft prevention of the photovoltaic panel. The circuits may avoid power conversion, for instance DC/DC power conversion, may avoid performing maximum power tracking to include a minimum number of components and thereby increase overall reliability.

A surge protective device includes an overvoltage protection circuit and a control module coupled to the overvoltage protection circuit that is configured to monitor at least one performance characteristic of the overvoltage protection circuit and is further configured to communicate the at least one performance characteristic to a destination external to the surge protective device.

An over-voltage protection system is provided for use with electrical equipment. The system includes a protection circuit having a first bus for receiving electrical power, a second bus for providing power to the equipment and two parallel surge arresters connected between the first bus and ground. A main and backup bushing are arranged in parallel between the first and second bus. The main bushing is arranged in series with a normally closed contact maintaining the main bushing in service by default. The backup bushing is arranged in series with a normally open contact isolating the backup bushing by default. The protection circuit comprises a controller for testing the insulation of the arresters and bushings. The controller is configured to selectively actuate the contacts to selectively isolate, or incorporate, the arresters and bushings in the circuit to facilitate testing and maintenance while maintaining the protection circuit operational.

Power outlets adapted for installation within an enclosure are provided. Power outlets are provided having a safety interlock adapted to prevent the creation of a hazardous condition within the enclosure as a result of the continued operation of an electrical device within the enclosed space. The safety interlock may include current limiting circuitry and hardware, hazard sensing devices interconnected with such current limiting circuitry and hardware or other circuit breaker switches, and combinations of such safety interlocks.

The invention relates to an elevator comprising at least one elevator car moved by at least one elevator motor, which elevator motor is driven by a frequency converter controlled by a control device of the elevator, the frequency converter comprising a rectifier bridge, an inverter bridge and a DC link connected in-between, the inverter bridge being connected to the elevator motor and the rectifier bridge being connected to AC mains via three phase supply lines comprising an LCL-filter and a mains switch. The elevator further comprises a backup power supply and a safety device of the control device, which in case of a mains power failure is configured to switch off the mains switch and to connect the backup power supply to the DC link and/or to at least one phase supply line, whereby the rectifier bridge is a bidirectional rectifier bridge being configured to convert DC supplied to the DC link from the backup power supply to an AC voltage supplied to at least two of the phase supply lines connected with at least one load circuit. An earth fault protection circuit for the load circuit is connected between earth and a common terminal of the capacitors of the LCL filter for monitoring an earth fault indicating signal, and which earth fault protection circuit is configured to issue an earth fault signal and/or initiating earth fault safety measures, dependent on the earth fault indicating signal.