Disclosed herein is a liquid system tool having an integrated residual current device, RCD. The liquid system tool comprises a current circuit having a power input for receiving an alternating electrical current, AC, a rectifier for rectifying the AC into a direct current, DC, a voltage booster for increasing a DC voltage and a motor unit connected to an output of the voltage booster for driving the liquid system tool. The RCD comprises a sensor element connected to an output of the rectifier and an input of the voltage booster and being configured to collect an analog current signal and an analog to digital, A/D, converter configured to convert the analog current signal into a digital current signal. The integrated RCD further comprises a logic unit connected to the A/D converter, wherein the logic unit is configured to evaluate the digital current signal and compare it to a current requirement, and wherein if the logic unit determines that the digital current signal does not fulfill the current requirement, it is further configured to break the current circuit so that no current can flow in the liquid system tool. Also disclosed is a method for detecting residual current in a liquid system tool, and a computer program product.

An electric-motor driving device includes an inverter connected to terminals connected to windings of an electric motor including the windings, the inverter applying an alternating-current voltage to the electric motor, a switching unit connected to the terminals and capable of switching a connection state between the terminals, a detecting unit that detects at least one of a voltage and an electric current of the inverter, and a control unit that determines on the basis of a detection value detected by the detecting unit that an abnormality occurs in the switching unit and controls the inverter to short-circuit at least two of the terminals.

An electrical combination, a motorized device system, a motor assembly, a battery pack, and operating methods. The combination may include an electrical device including a device housing, a load supported by the device housing, the load being operable to output at least about 1800 watts (W), and a device terminal electrically connected to the load; a battery pack including a pack housing, battery cells supported by the pack housing, the battery cells being electrically connected and having a nominal voltage of up to about 20 volts, and a pack terminal electrically connectable to the device terminal to transfer current between the battery pack and the electrical device; and a controller operable to control the transfer of current.

According to some embodiments, system and methods are provided, comprising an electrical installation; one of a permanent magnet motor and a permanent magnet generator; a circuit operative to provide current to operate one of the motor and the generator; one or more sensors coupled to the electrical installation, wherein the one or more sensors are operative to detect an overcurrent in the circuit and to generate an overcurrent signal; one or more inductors; and an inductance module control operative to: receive the overcurrent signal from the one or more sensors; determine how to insert one or more inductors to reduce an amplitude of the overcurrent; activate the one or more inductors based on the determination; and deactivate the one or more inductors when the overcurrent is not detected. Numerous other aspects are provided.

A wireless relay may include a housing; an output, disposed within the housing; and a wireless interface, disposed within the housing, wherein the wireless interface is to receive wireless communication signals including settings to configure one or more functionalities associated with the wireless relay.

Provided are a method and apparatus for determining motor temperature, and a storage medium. The method includes: obtaining an electromagnetic loss of each node in nodes acquired by decomposing components of a motor, wherein the is a natural number greater than 1, and at least one component in the components of the motor is decomposed into multiple nodes in the nodes; obtaining a thermal resistance between every two nodes in the nodes; and determining a temperature of the motor based on the electromagnetic loss of the each node in the nodes and the thermal resistance between the every two nodes in the nodes.

The present disclosure relates to an electronic circuit for detecting the current winding temperature of phase windings and/or other characteristics of an electronically commutated electric motor, which is connected, or can be connected, to a frequency converter, comprising one or more capacitive two-terminal networks with a temperature-dependent impedance, each network being arranged parallel to two winding terminals (u, v, w) of the phase windings, as well as a detector for detecting the current responses in the motor feeds on the basis of steep-flanked voltage changes at the output of the frequency converter.

A solid state circuit breaker, including a solid state switch, an inductor connected with the solid state switch in series and a fault detection circuit. The solid state switch has a gate electrode, a source electrode and a drain electrode. The fault detection circuit is used for detecting health status of the solid state switch and identifying fault type of the solid state switch in a condition that a fault occurs on the solid state switch based on one or more of a measured voltage between the source electrode and the drain electrode of the solid state switch, a measured voltage of two terminals of the inductor, a reference voltage and a switching control signal provided to the gate electrode of the solid state switch. A motor driving system having the solid state circuit breaker is further disclosed.

A hybrid air-gap/solid-state device protection device (PD) for use in an electrical power distribution system includes an air-gap disconnect unit connected in series with a solid-state device, a sense and drive circuit, and a microcontroller. Upon the sense and drive circuit detecting an impending fault or exceedingly high and unacceptable overvoltage condition in the PD's load circuit, the sense and drive circuit generates a gating signal that quickly switches the solid-state device OFF. Meanwhile, the microcontroller generates a disconnect pulse for the air-gap disconnect unit, which responds by forming an air gap in the load circuit. Together, the switched-OFF solid-state device and air gap protect the load and associated load circuit from being damaged. They also serve to electrically and physically isolate the source of the fault or overload condition from the remainder of the electrical power distribution system.

A central vacuum cleaning system including a receptacle for receiving dirt; conduits terminating in valves to which a flexible hose may be attached; a motor for generating airflow through the conduits to the receptacle; a motor control circuit controlling power to the motor; and a remote module receiving, through a communications medium from the motor control circuit, signals indicating an operating condition of the central vacuum cleaning system.