A short circuit detection circuit includes a current terminal, a sense resistor, an amplifier, and a resistor-capacitor ladder. The sense resistor is coupled to the current terminal, and is configured to develop a sense voltage proportional to a current through the current terminal. The amplifier is coupled to the sense resistor, and is configured to generate a scaled current proportional to the sense voltage. The resistor-capacitor ladder is coupled to the amplifier, and is configured to generate a measurement voltage that represents a surface temperature rise due to the current through the current terminal.

An apparatus according to an embodiment includes a control circuit to control operations of an inverter and a switch. The control circuit judges whether or not a power system has a power failure, based on values of the system voltage and a frequency of the power system; and calculates a phase difference between a phase of the output voltage of the inverter and a phase of the system voltage and generate, by means of the phase difference, an output frequency pattern for changing a frequency of the output voltage of the inverter. The control circuit, when it is judged that the power system has recovered from the power failure, controls the inverter to change the frequency of the output voltage of the inverter in line with the output frequency pattern, and closes the switch after the phase difference becomes smaller than or equal to a threshold.

A power converter can include a magnetic energy storage element, a main switch, a synchronous rectifier switch, and an energy recovery circuit. The energy recovery circuit can include a resonant circuit and an auxiliary switch configured to operate in conjunction with the main and synchronous rectifier switches to store energy in the resonant circuit and deliver energy therefrom to reduce switching losses associated with the main and synchronous rectifier switches. The converter can be a buck, boost, buck-boost, or other converter type. The auxiliary switch may be operated according to a two-pulse control mode or using a conventional buck converter controller with additional delay elements. The resonant circuit inductance may be a discrete inductor or a parasitic inductance, such as a PCB trace, which may be designed to provide a desired inductance value selected to efficiently provide sufficient energy to achieve reduced switching losses of the main and auxiliary switches.

Embodiments include redundant power supplies and method for fault detection in a redundant power supply. Aspects include monitoring a voltage at local output nodes of each phase of the redundant power supply, wherein the local output nodes are each connected to an output bus of the redundant power supply via a feedback path. Aspects also include creating an alert that a phase associated with the local output node has failed based on a determination that the voltage at the local output node is within a fault range.

Various examples are directed to a solar power electrolyzer system comprising a first electrolyzer stack, a second electrolyzer stack, a first converter and a first converter controller. The first electrolyzer stack may be electrically coupled in series with a photovoltaic array. The first converter may be electrically coupled in series with the first electrolyzer stack and electrically coupled in series with the photovoltaic array. The second electrolyzer stack electrically may be coupled at an output of the first converter. The first converter controller may be configured to control a current gain of the first converter.

Electric power is transferred to an electric load as alternating current over at least two incoming and outgoing lines. At least one line circuit manages at least one parameter of the transferred electric power. A central circuit exchanges data and/or commands with the at least one line circuit over a respective galvanically isolated communication interface, such that a reference potential of the central circuit is floating relative to an earth potential of the at least two incoming and outgoing lines. A respective surge protection capacitor is arranged in parallel with each galvanically isolated communication interface. The surge protection capacitors are configured to accumulate a respective fraction of an electric charge resulting from an undesired overvoltage on one of said incoming lines so as to split up the undesired overvoltage into two or more voltages over the galvanically isolated communication interfaces each of which voltage is smaller than the undesired overvoltage.

A voltage level detector includes a voltage divider that generates a first division voltage and a second division voltage. A first comparator compares any one of the first and second division voltages with a reference. A second comparator compares the other of the first and second division voltages with the reference. A first switch converts a connection path between the first and second division voltages and the first and second comparators based on a clock signal. A determination circuit determines, based on a first comparison signal and a second comparison signal, whether the voltage level detector is normal. A second switch converts a connection path between the first and second comparison signals and input terminals of the determination circuit based on the clock signal.

A power delivery system includes a power sourcing equipment, a powered device and a transmission cable. When the power sourcing equipment is electrically connected to the powered device via the transmission cable, an over-current detecting circuit in the power sourcing equipment is configured to detect over-current occurrence of the powered device. Meanwhile, the power sourcing equipment is configured to determine the functionality of the over-current detecting circuit based on its specific pin and provide single fault protection when the over-current detecting circuit fails.

A wall-mountable load control device may include an illuminated rotary knob for providing a nightlight feature. The load control device may be configured to control an intensity of a lighting load. The load control device may include a yoke adapted to be mounted to an electrical wall box, an enclosure attached to the yoke, a faceplate attached to the yoke and having an opening, a mounting member attached to the yoke, and/or a potentiometer located within the enclosure and having a shaft extending through an opening in the yoke and the opening of the faceplate. The load control device may include a collar attached to the boss of the mounting member and surrounding the shaft of the potentiometer. The mounting member may be configured to conduct light from at least one light source housed within the enclosure to illuminate the faceplate.

A load regulation device for controlling the amount of power delivered to an electrical load may be able to calibrate the magnitude of an output voltage of the load regulation device in order to control the magnitude of a load voltage across the electrical load to a predetermined level. The load regulation device may receive the feedback from a calibration device adapted to be coupled to load wiring near the electrical load. The feedback may indicate when the magnitude of the load voltage across the electrical load has reached a predetermined level. The load regulation device may gradually adjust the magnitude of the output voltage, receive the feedback from the calibration device, and then use the feedback to determine the magnitude of the output voltage corresponding to when the magnitude of the load voltage across the electrical load has reached the predetermined level.