A thermostat may include first and second solid-state switching elements coupled to a call relay wire connector and a power return wire connector. The switching elements may be configured to operate in a first state to make a connection between the call relay wire connector and the power return wire connector, and a second state in which the connection is interrupted. The thermostat may also include power monitoring circuitry configured to cause the switching elements to operate in the first state to actuate an environmental control function, receive an indication that the switching elements should transition to the second state, at a first time after receiving the indication, turn off whichever of the first switching element and the second switching element receives AC current from the environmental control system at the first time; and at a second time after the first time, turn off the other of the switching elements.

In one example, a circuit includes a first voltage converter and a second voltage converter. The first voltage converter is configured to convert a first voltage to a second voltage, determine whether the first voltage converter is operating in an unsafe state, and output an indication that the first voltage converter is operating in the unsafe state. The second voltage converter is configured to selectively activate a high side switch and a low side switch to convert the second voltage to a third voltage. In response to receiving the indication that the first voltage converter is operating in the unsafe state, the second voltage converter is further configured to activate the high side switch and the low side switch to establish an electrical path between the second voltage and a reference node of the circuit.

A wireless electric vehicle charging system comprises base-side equipment for generating a magnetic field and vehicle-side equipment for receiving energy via the magnetic field to supply power to a vehicle-driving battery. Monitoring circuitry monitors one or more of voltage, current, or phase associated with the base-side equipment and halts generation of the magnetic field in response to a change in the voltage, current, or phase associated with the operation of the base-side equipment that indicates a fault condition at the vehicle-side equipment, which may include a loss of power or disconnection of a battery. Based on detection of the change, the monitoring circuitry can halt generation of the magnetic field to prevent damage at the vehicle-side equipment.

A protective device including: a plurality of line terminals and a plurality of load terminals a circuit interrupter including a solenoid and a set of interrupting contacts that connect at least one line terminal and at least one load terminal in a reset state and disconnect the at least one line terminal and the at least one load terminal in a tripped state; a voltage detection element configured to detect voltage across the plurality of line terminals and generate a line voltage rejection signal when greater than a predetermined overvoltage; a reset assembly including a reset button and a reset switch operatively coupled to the reset button; and a reset prevention mechanism configured to prevent the circuit interrupter from entering the reset state when the reset signal is absent.

A protective device including: a plurality of line terminals and a plurality of load terminals a circuit interrupter including a solenoid and a set of interrupting contacts that connect at least one line terminal and at least one load terminal in a reset state and disconnect the at least one line terminal and the at least one load terminal in a tripped state; a voltage detection element configured to detect voltage across the plurality of line terminals and generate a line voltage rejection signal when greater than a predetermined overvoltage; a reset assembly including a reset button and a reset switch operatively coupled to the reset button; and a reset prevention mechanism configured to prevent the circuit interrupter from entering the reset state when the reset signal is absent.

Even when an overvoltage suppression circuit is not formed due to failure of an overvoltage suppression switch, overvoltage application to semiconductors and a filter capacitor is prevented. A control unit controls the overvoltage suppression circuit to short-circuit the filter capacitor when the voltage thereacross exceeds a predetermined value. Then when non-operation of the overvoltage suppression circuit is detected, the control unit opens an AC breaker and AC switch, and closes a charging switch. Thereafter, the control unit turns ON the converter element (or converter element) connecting to the filter capacitor terminal (or terminal) and a charging resistor, and turns ON converter element (or converter element) connecting to terminal (or terminal) of filter capacitor and connecting to the terminal of the transformer not connected to charging resistor.

Even when an overvoltage suppression circuit is not formed due to failure of an overvoltage suppression switch, overvoltage application to semiconductors and a filter capacitor is prevented. A control unit controls the overvoltage suppression circuit to short-circuit the filter capacitor when the voltage thereacross exceeds a predetermined value. Then when non-operation of the overvoltage suppression circuit is detected, the control unit opens an AC breaker and AC switch, and closes a charging switch. Thereafter, the control unit turns ON the converter element (or converter element) connecting to the filter capacitor terminal (or terminal) and a charging resistor, and turns ON converter element (or converter element) connecting to terminal (or terminal) of filter capacitor and connecting to the terminal of the transformer not connected to charging resistor.

To protect an electrical load connected to an output port from anomalous electricity in an apparatus that provides output electricity at the output port from input electricity accepted through an input port thereof, an input sensing unit is electrically connected to the input port and configured to indicate an overvoltage event. A power control unit generates, responsive to the overvoltage event, a modulation signal that defines at least one amplitude notch of variable temporal width. A switching mechanism electrically interposed between the input port and the output port transitions into conducting and non-conducting states in accordance with the modulation signal to superimpose the amplitude notch on electricity conveyed to the output port through the switching mechanism.

To protect an electrical load connected to an output port from anomalous electricity in an apparatus that provides output electricity at the output port from input electricity accepted through an input port thereof, an input sensing unit is electrically connected to the input port and configured to indicate an overvoltage event. A power control unit generates, responsive to the overvoltage event, a modulation signal that defines at least one amplitude notch of variable temporal width. A switching mechanism electrically interposed between the input port and the output port transitions into conducting and non-conducting states in accordance with the modulation signal to superimpose the amplitude notch on electricity conveyed to the output port through the switching mechanism.

To protect a connected electrical load from anomalous electricity, an apparatus has a condition sensing unit configured to distinguish a power event type from among power event types from characteristics of an input electricity waveform accepted through an input port. The condition sensing unit indicates the power event type when a corresponding overvoltage criterion is met by characteristics of the input electricity waveform. A power control unit generates, responsive to a power event, a modulation signal that defines at least one amplitude notch in the input electricity waveform in accordance with the power event type. A switching mechanism electrically interposed between the input port and the output port transitions into conducting and non-conducting states in accordance with the modulation signal to superimpose the notch on the input electricity waveform.