Circuits, methods, and apparatus that may provide power supply voltages in a safe and reliable manner that meets safety and regulatory concerns and does not exceed physical limitations of cables and other circuits and components used to provide the power supply voltages. One example may provide a cable having a sufficient number of conductors to provide power without exceeding a maximum current density for the conductors. Another example may provide a cable having more than the sufficient number of conductors in order to provide an amount of redundancy. Current sense circuits may be included for one or more conductors. When an excess current is sensed, a power source in the power supply may be shut down, the power source may be disconnected from one or more conductors, or both events may occur.

Circuits, methods, and apparatus that may provide power supply voltages in a safe and reliable manner that meets safety and regulatory concerns and does not exceed physical limitations of cables and other circuits and components used to provide the power supply voltages. One example may provide a cable having a sufficient number of conductors to provide power without exceeding a maximum current density for the conductors. Another example may provide a cable having more than the sufficient number of conductors in order to provide an amount of redundancy. Current sense circuits may be included for one or more conductors. When an excess current is sensed, a power source in the power supply may be shut down, the power source may be disconnected from one or more conductors, or both events may occur.

A protection circuit, comprising: a transient suppression circuit, configured to suppress a transient voltage; and a short-circuit protection circuit connected between the transient suppression circuit and a ground terminal, wherein when the transient suppression circuit is shorted out and the transient voltage is a protection voltage, the short-circuit protection circuit disconnects a loop where the transient suppression circuit is located. The short-circuit protection circuit has a turned-on state and a turned-off state; the short-circuit protection circuit is in a turned-on state when the transient suppression circuit is shorted out and the transient voltage is greater than the protection voltage; and the short-circuit protection circuit is in a turned-off state when the transient suppression circuit is shorted out and the transient voltage is a protection voltage.

A high-voltage protection module for a metrology device includes a metal-oxide varistor (MOV) coupled across a mains power line, a resistor electrically coupled to the MOV in series with the MOV, and a fuse electrically coupled to the MOV and the resistor in series, the resistor being located between the fuse and the MOV. The fuse opens upon an overvoltage event disengaging alternating current (AC) power from the mains power line to the metrology device.

A high-voltage protection module for a metrology device includes a metal-oxide varistor (MOV) coupled across a mains power line, a resistor electrically coupled to the MOV in series with the MOV, and a fuse electrically coupled to the MOV and the resistor in series, the resistor being located between the fuse and the MOV. The fuse opens upon an overvoltage event disengaging alternating current (AC) power from the mains power line to the metrology device.

An irrigation controller comprising a housing, a control circuit having a processor and a memory, the control circuit configured to store and execute an irrigation schedule, an input connector configured to be coupled to an alternating current (AC) power supply and receive an AC power signal having a first voltage level, a transformer disposed at least partially in the housing, the transformer having a primary side and a secondary side, wherein the primary side is coupled to the input connector, a resettable fuse disposed at least partially in the housing, the fuse being electrically coupled in series between the input connector and the primary side of the transformer, driver circuitry disposed in the housing and electrically coupled to the secondary side of the transformer, and wherein the driver circuitry is coupled to the control circuit, and an output connector coupled to the driver circuitry.

Disclosed in the present invention is a novel overvoltage protective device for lightning protection, comprising a first varistor, a second varistor, a PTC Thermistor, and lead-out terminals. The first varistor and the PTC Thermistor are connected in parallel, and then further connected in series with the second varistor to form a single port combined circuit. The surge-withstand capability of the first varistor is higher than the surge-withstand capability of the second varistor. At least one of the two lead-out terminals of the single port combined circuit is a thermally-conductive end with low thermal resistance. The second varistor is thermally coupled to the PTC Thermistor. The thermally-conductive end with low thermal resistance is thermally coupled to one or both of the second varistor and the PTC Thermistor.

A system and method for autonomous monitoring and active defense of lightning includes: a current sensor installed on a metal object that easily forms an upward connecting leader and easily monitors a pulse current formed thereby, which is configured to monitor a current pulse signal generated by the upward connecting leader; an antenna installed near the current sensor, which is configured to monitor a field pulse signal generated by a downward stepped leader; a signal processing and warning module (SPWM), which is configured to detect received current and field pulse signals, and issuing an early warning signal when detecting origination and development of pulses of the downward stepped leader and the upward leader, wherein the early warning signal is sent to a controlled surge protection device (CSPD) and/or a polarized reconfigurable lightning protection antenna, and the CSPD completes on/off actions before a first return stroke and/or the lightning protection antenna becomes only to receive/transmit horizontally polarized electromagnetic waves. According to the present invention, lightning strike defense can be achieved before the first return stroke, with low cost, simplicity and reliability.

A system and method for autonomous monitoring and active defense of lightning includes: a current sensor installed on a metal object that easily forms an upward connecting leader and easily monitors a pulse current formed thereby, which is configured to monitor a current pulse signal generated by the upward connecting leader; an antenna installed near the current sensor, which is configured to monitor a field pulse signal generated by a downward stepped leader; a signal processing and warning module (SPWM), which is configured to detect received current and field pulse signals, and issuing an early warning signal when detecting origination and development of pulses of the downward stepped leader and the upward leader, wherein the early warning signal is sent to a controlled surge protection device (CSPD) and/or a polarized reconfigurable lightning protection antenna, and the CSPD completes on/off actions before a first return stroke and/or the lightning protection antenna becomes only to receive/transmit horizontally polarized electromagnetic waves. According to the present invention, lightning strike defense can be achieved before the first return stroke, with low cost, simplicity and reliability.

Certain aspects of the present disclosure provide circuitry connecting an output of voltage reference circuitry powered by a relatively high voltage to an input of a voltage buffer configured to generate a voltage lower than the high voltage. The connecting circuitry prevents the high voltage from reaching the input of the voltage buffer. One example electronic circuit generally includes a voltage reference circuit configured to be powered by a relatively higher voltage, a buffer circuit configured to generate a relatively lower voltage as compared to the relatively higher voltage, and circuitry coupled between an output of the voltage reference circuit and an input of the buffer circuit, the circuitry being configured to prevent the higher voltage from reaching the input of the buffer circuit.