A circuit breaker includes main contacts movable between closed and open positions such that a line terminal and a load terminal are, respectively, in electrical communication or electrically isolated. A trip coil is connected to the contacts, causing the contacts to move from the closed position to the open position in response to a trip current, thereby tripping the circuit breaker. A normally closed relay having a relay activating circuit and a switching circuit is provided, with the switching circuit being electrically connected to the trip coil. A monitoring circuit is electrically connected to the relay activating circuit, supplying activating power to the relay activating circuit so long as a determination is made that the breaker is operating within acceptable parameters, and ceasing to supply activating power to the relay activating circuit upon a determination being made that the breaker is not operating within acceptable parameters, thereby tripping the breaker.

Operation coil drive device of electromagnetic contactor includes current detector and drive controller. The detector, when switching control is performed on operation coils of the contactor, detects coil current flowing through the coils. The controller controls an on/off time ratio of a semiconductor switching element wherein the on/off time ratio during close circuit control becomes larger than the on/off time ratio during holding control. Power supply voltage is switchingly applied to the coils at the on/off time ratio. The controller includes a determination locus setter and a close circuit state determiner. The setter sets a determination locus that continuously increases along a change locus of detected coil current during close circuit control. The determiner determines a contact point close circuit state by contact of a movable contact to a fixed contact based on deviation between the determination locus by the setter and the detected coil current detected.

A controller for an alternating current contactor includes: a filtering and rectification circuit that filters and rectifies external alternating current; an electromagnet component driven by an output of the filtering and rectification circuit that performs actions of attraction, holding or releasing; a power transistor circuit connected to the electromagnet component; and a microcontroller that controls the power transistor circuit to control the actions performed by the electromagnet component. The controller further includes a voltage control loop that provides a voltage feedback signal and a current control loop that provides a current feedback signal to the microcontroller. The microcontroller generates a control signal according to the voltage feedback signal. The control signal is a PWM control signal having different duty cycles during the attraction and holding of the electromagnet component so that the current does not exceed a predetermined current threshold during the attraction and bolding of the electromagnet component.

A power cable assembly includes a power cable extending between a first end and a second end having a hot conductor and a neutral conductor. The power cable assembly includes a circuit protection device along the power cable between the first and second ends. The circuit protection device has a ground fault circuit interrupt (GFCI) device configured to sense a current difference on the hot and neutral conductors to initiate a triggering event. The circuit protection device has a high-power relay device connected to the GFCI device. The high-power relay device is connected to the hot conductor and is configured to open the hot line when the triggering event is initiated by the GFCI device.

A PCB motor controller comprises relays mounted on a PCB and interconnected to power traces in or on the PCB to receive incoming three-phase power and to output three-phase power to a motor. Control power traces in or on the PCB connect the relays to control circuitry, also mounted on the PCB. A power supply is mounted on the PCB and connected to the control circuitry to provide power for its operation and for switching of the relays. The relays are switched in accordance with a point-on-wave (POW) switching scheme, allowing for the use or relays and the PCB, which may not otherwise be suitable for motor control applications.

A PCB motor controller comprises relays mounted on a PCB and interconnected to power traces in or on the PCB to receive incoming three-phase power and to output three-phase power to a motor. Control power traces in or on the PCB connect the relays to control circuitry, also mounted on the PCB. A power supply is mounted on the PCB and connected to the control circuitry to provide power for its operation and for switching of the relays. The relays are switched in accordance with a point-on-wave (POW) switching scheme, allowing for the use or relays and the PCB, which may not otherwise be suitable for motor control applications.

The present application discloses a contactor coil control circuit, including a switch control circuit, a drive circuit, a fast turn-off circuit, a diode D1, a first MOS (Metal Oxide Semiconductor) transistor TR1 and a contactor coil. The fast turn-off circuit at least includes an MOS transistor TR2 or a triode; the cathode of the diode is connected to an input voltage VIN; the anode of the diode is connected to a first port of the fast turn-off circuit; a second port of the fast turn-off circuit is connected to the drain of the first MOS transistor; the source of the first MOS transistor is grounded; one end of the contactor coil L1 is connected to an input voltage, and the other end of the contactor coil is connected to the drain of the first MOS transistor; a third port of the fast turn-off circuit is connected to an output port of the drive circuit; an input port of the drive circuit is connected to a first output port of the switch control circuit; and a second output port of the switch control circuit is connected to the gate of the first MOS transistor. On the premise of turning off the contactor quickly, the coil control circuit is lower in loss, adopts a fewer of devices, and is lower in cost and smaller in volume.

A control apparatus for a relay and controlling method thereof. The controlling method includes: detecting an input voltage of the relay and a current flowing through the relay; obtaining a voltage zero crossing point information according to the input voltage and a reference voltage value; turning on the relay at an initial turn-on time point according to the voltage zero crossing point information, and obtaining a real turn-on time point of the relay according to the current flowing through the relay; obtaining a turn-on delay of the relay according to the initial turn-on time point and the real turn-on time point, and adjusting the initial turn-on time point to obtain a compensated turn-on time point according to the turn-on delay.

The constant voltage supplying circuit for a circuit breaker according the invention comprises: a first switching device; a constant current source configured to supply a constant current; a feedback circuit section commonly connected to an output terminal of each of the first switching device and the constant current source; a constant voltage source connected to the feedback circuit section, and configured to supply a constant voltage; a current adjusting circuit section connected to the output terminal of the first switching device, and configured to adjust an output current of the first switching device; and a divided voltage resistor section including a first resistor and a second resistor, and configured to provide a divided voltage of an output voltage of the constant voltage supplying circuit, to the feedback circuit section, through a connection node between the first resistor and the second resistor.

Provided is a capacitor discharge device that quickly and safely discharges a capacitor charged with energy inside a sub-module of an MMC converter, the device including: a capacitor storing a DC voltage inside a sub-module of an MMC converter; a power supply unit supplying operating power required in the submodule by using the voltage stored in the capacitor; a first resistor connected in parallel to the capacitor; a second resistor having a lower resistance value and a larger heat capacity than the first resistor so as to rapidly discharge the capacitor storing the voltage; a first switching contact connecting and disconnecting the capacitor and the second resistor; a switching unit operating switching of the first switching contact by the operating power; a second switching contact connecting and disconnecting the power supply unit and the switching unit; and a control unit operating switching of the second switching contact.