A load control device for controlling the power delivered from an AC power source to an electrical load includes a thyristor, a gate coupling circuit for conducting a gate current through a gate of the thyristor, and a control circuit for controlling the gate coupling circuit to conduct the gate current through a first current path to render the thyristor conductive at a firing time during a half cycle. The gate coupling circuit is able to conduct the gate current through the first current path again after the firing time, but the gate current is not able to be conducted through the gate from a transition time before the end of the half-cycle until approximately the end of the half-cycle. The load current is able to be conducted through a second current path to the electrical load after the transition time until approximately the end of the half-cycle.

To achieve a size reduction by on-off controlling non-contact switching devices with a microcomputer. When a three-phase alternating-current electric motor is to be used, lead wires of the three-phase alternating-current electric motor are connected to output terminals of a control board. When a single-phase alternating-current electric motor is to be used, two supply terminals of the control board are electrically connected together through a first connecting member, and one end of the first connecting member is defined as a single-phase alternating-current power supply terminal. A second connecting member is connected to a supply terminal, and one end of the second connecting member is defined as a single-phase alternating-current power supply terminal. A main winding of the single-phase alternating-current electric motor is connected to the output terminals, and an auxiliary winding is connected to the output terminal and the second connecting member.

Power to an electrical device is controlled using a phase control that changes a cutoff phase of an alternating current (AC) electrical signal delivered to the electrical device. The power delivered to the electrical device is increased to an operational level using the phase control. A level of the power delivered to the electrical device is maintained at the operational level using an integral half cycle control that selectively removes a plurality of half cycles from the AC electrical signal delivered to the electrical device such that a plurality of remaining half cycles in the AC electrical signal delivered to the electrical device have a frequency outside a range of sub-harmonic frequencies.

A power supply system for an electric arc furnace includes an AC input connectable to an electrical grid and an AC output for supplying at least one power electrode of the arc furnace; a resonant circuit interconnected between the AC input and the AC output. The resonant circuit includes a controllable bypass switch for connecting and disconnecting a circuit input and a circuit output of the resonant circuit and a capacitor and a main inductor connected in parallel with the bypass switch.

A drive circuit for driving an electro-optical device like an optically switchable glazing, e.g. a glass panel provided with a PDLC or SPD layer, comprises a set of input terminals for receiving an alternating input voltage at a first frequency; a set of output terminals for supplying an alternating output voltage at a second frequency; a control circuit generating a control signal dependent on an input signal, the input signal representing a charge state of the electro-optical device; and a current-direction circuit for controlling a current-flow direction of an electrical current in response to the control signal. The control circuit and the current-direction circuit are thereby configured to control the second frequency such that the electro-optical device is prevented from degradation, while keeping an energy consumption low.

Provided is an electronic device which can easily measure a standby current of an internal circuit of an electronic device after burn-in. The electronic device includes: a power source terminal; a regulator that generates a predetermined voltage from a voltage of the power source terminal; an internal circuit that is operated by an output voltage of the regulator; and a standby terminal through which the regulator and the internal circuit are set to a low power consumption state.

A dimmer is provided for controlling power to a load, the dimmer having a ground leakage power supply deriving power from a connection of the dimmer to ground. The power supply may be a switching-mode power supply that can be the sole or primary power supply to power operation of the dimmer, including operation of the controller.

Aspects of the disclosure provide a method that including receiving a sensed signal corresponding to a current flowing through an energy transfer module in response to an on/off state of a forward-type triode for alternating current (TRIAC), determining the TRIAC on/off state based on the sensed signal, and controlling the energy transfer module based on the determined TRIAC on/off state.

A dimmer is provided for controlling power to a load, the dimmer having a ground leakage power supply deriving power from a connection of the dimmer to ground. The power supply may be a switching-mode power supply that can be the sole or primary power supply to power operation of the dimmer, including operation of the controller.

Techniques for an electronic device to perform power-stealing techniques to harvest energy from a power-control circuit to power components of the electronic device. In some examples, the electronic device may be connected in the power-control circuit between a power supply and a relay that is selectively configured to activate a power load. According to the techniques described herein, the electronic device may include voltage-drop circuitry that is connected in the power-control circuit such that a voltage drop is produced across electrical components of the electronic device while the relay is in the activated, or triggered, state. In this way, the electronic device may perform power-stealing from the power-control circuit while the relay is maintained in the activated state.