A circuit breaker comprises a solid-state bidirectional switch, a switch control circuit, current and voltage sensors, and a processor. The solid-state bidirectional switch is connected between a line input terminal and a load output terminal of the circuit breaker, and configured to be placed in a switched-on state and a switched-off state. The switch control circuit control operation of the bidirectional switch. The current sensor is configured to sense a magnitude of current flowing in an electrical path between the line input and load output terminals and generate a current sense signal. The voltage sensor is configured to sense a magnitude of voltage on the electrical path and generate a voltage sense signal. The processor is configured to process the current and voltage sense signals to determine operational status information of the circuit breaker, a fault event, and power usage information of a load connected to the load output terminal.

According to one embodiment, an excitation inrush current suppressing apparatus comprising: bus voltage measurement equipment which measures each phase voltage of the single-phase AC-side bus; transformer voltage measurement equipment which measures a single-phase-side voltage of the transformer; phase detector which detects a cutoff phase when opening the circuit breaker by monitoring each phase voltage measured by the bus voltage measurement equipment and the single-phase-side voltage measured by the transformer voltage measurement equipment, holds the detected cutoff phase, and outputs the same phase as the held cutoff phase; and close command output device which closes the circuit breaker by the same voltage phase as the cutoff phase output from the phase detector.

An electric power distribution switchgear is connected between an electric power grid and an electric power equipment. The switchgear includes a synchronized vacuum switching apparatus configured to break the current to the electric power equipment using a synchronized technique to avoid re-ignition during the breaking and thus any transients caused by such re-ignition; and a surge arrester arrangement connected to the electric power equipment, the surge arrester arrangement being designed and configured to only handle transients caused by the current chopping at the breaking. The surge arrester arrangement can be arranged remote from the electric power equipment, such as e.g. in the same casing as the synchronized vacuum switching apparatus.

A simple, economically efficient, synchronized switching system for control of a three phase motor contactor utilizes only Voltage monitoring to determine zero crossings and knowledge of the sinusoidal power waveforms and operational delay period of the contactor, to synchronize operation of the contacts at low power. The phases can be serially utilized for zero crossing detection upon Close or Open commands, so as to spread the wear over each set of contacts. Expensive metal at the contact surfaces can therefore be used more efficiently. For arc energy reduction upon contact opening, knowledge of Line-Load Voltage on at least one phase can be used to derive an empirical determination of the voltage angle at opening which yields the lowest arc energy.

A switching apparatus is disclosed for switching a current, formed using a phase conductor and a switch arranged in the phase conductor, for the purpose of switching a transmission of current via the phase conductor. In addition, the switching apparatus includes a circuit for deriving a test current from the phase conductor via a ground conductor; a sensing apparatus for detecting the test current and an evaluation apparatus for evaluating the detected test current. A control apparatus is used to control closing of the switch arranged in the phase conductor. The evaluation apparatus is configured to detect a zero crossing for an alternating current and the control apparatus is set up to prompt closing of the switch arranged in the phase conductor in accordance with the time of the zero crossing. An embodiment reduces abrasion or wear on the switch as a result of short-circuit currents during switching-on.

A system and methods providing for minimizing the arc energy delivered to the pads of a plurality of contactors using a single control coil based on monitoring the electrical sine waves of the three alternating current electrical poles and calculating the instant to energize or deenergize a single control coil. The remainder of the contactors will make or break based on an offset in time from the making or breaking of the control contactor.

A method and apparatus using electromagnetic switching in a two-step connection process is provided to minimize surge currents and torque oscillations in three-phase motors during starts.

Switching device (1) for operating at least one load, comprising at least one switching unit (7; 8; 9), which switches a tapped current phase (L) to a load (2-1; 2-2; 2-3) connectable to the switching unit (7; 8; 9) to supply said load with current and which has a measurement unit (7C; 8C; 9C) which measures a current phase progression of the at least one current phase (L); a local control unit (18), which after receiving a control command from an external control system (24) actuates a semiconductor switch (7B; 8B; 9B) of the switching unit (7; 8; 9) in such a way that the semiconductor switch (7B; 8B; 9B) switches at a zero of the current phase (L) measured by the measurement unit (7C; 8C; 9C), and a local monitoring unit (20), which evaluates the current phase progression, measured by the measurement unit (7C; 8C; 9C), of the at least one current phase (L) to detect an operational deviation from a normal current supply to the associated load (2-1; 2-2; 2-3) connected to the switching unit (7; 8; 9), and reports any detected operational deviation.

In aspects, the present invention discloses a method of determining an electrical operating time of a circuit breaker (140) in a multiphase electrical system having a subsystem (160) connectable to a power source (110) through a circuit breaker (140) operated by a controller (130). The controller is connected to a current transformer (120, 150) for measuring current of the subsystem in a one phase. The method comprises monitoring the current of the subsystem in the one phase, determining a first rate of change from the monitored current in the one phase, detecting an instance of switching in an another phase based on the first rate of change, and determining an electrical operating time of the circuit breaker in the another phase based on the detected instance of switching and an instance at which a command for switching in the another phase was provided to the circuit breaker.

One embodiment describes a method that includes determining a desired torque level of a motor actuated by a motor starter; determining, using a control system, a configuration of the motor starter to achieve the desired torque level, in which determining the configuration includes determining which of a plurality of switching devices in the motor starter should be opened and which should be closed; and instructing, using the control system, the motor starter to implement the determined configuration by opening or closing one or more of the plurality of switching devices.