Damages to the rectifying MOSFET in the secondary side of voltage converters are reduced or eliminated by inserting intermediary steps between detecting a dropping in the converter output voltage V.sub.CC and activating the under voltage lock out (UVLO) circuitry. During the intermediary steps, the timing for switching off the MOSFET is advanced to prevent the current flow in the MOSFET from reversing its direction.

Damages to the rectifying MOSFET in the secondary side of voltage converters are reduced or eliminated by inserting intermediary steps between detecting a dropping in the converter output voltage V.sub.CC and activating the under voltage lock out (UVLO) circuitry. During the intermediary steps, the timing for switching off the MOSFET is advanced to prevent the current flow in the MOSFET from reversing its direction.

Various embodiments disclosed herein provide techniques for detecting electrical arcing in an electrical system. The techniques include a network device receiving first voltage or current readings associated with a first power cycle, receiving second voltage or current readings associated with a second power cycle, determining that an electrical arcing condition is present by comparing the first voltage or current readings with the second voltage or current readings, and performing a remedial operation in response to determining that the electrical arcing condition is present.

Various embodiments disclosed herein provide techniques for detecting electrical arcing in an electrical system. The techniques include a network device receiving first voltage or current readings associated with a first power cycle, receiving second voltage or current readings associated with a second power cycle, determining that an electrical arcing condition is present by comparing the first voltage or current readings with the second voltage or current readings, and performing a remedial operation in response to determining that the electrical arcing condition is present.

A protective relay system includes plural protective relay devices protecting a power system based on electrical quantity data from the power system, and a communication between the protective power devices is performed via a network. The protective relay device includes a clock unit periodically clocking a timing at which sampling is performed on an electrical quantity of the power system, a relay computing unit performing a relay computation based on the electrical quantity data having undergone the sampling and electrical quantity data received via the network, a random-number creating unit creating a random number, and a synchronization-frame processing unit setting a timing of sending a synchronization frame to another protective relay device via the network based on the random number created by the random-number creating unit.

A protective relay system includes plural protective relay devices protecting a power system based on electrical quantity data from the power system, and a communication between the protective power devices is performed via a network. The protective relay device includes a clock unit periodically clocking a timing at which sampling is performed on an electrical quantity of the power system, a relay computing unit performing a relay computation based on the electrical quantity data having undergone the sampling and electrical quantity data received via the network, a random-number creating unit creating a random number, and a synchronization-frame processing unit setting a timing of sending a synchronization frame to another protective relay device via the network based on the random number created by the random-number creating unit.

A circuit interrupter is structured to electrically connect between a power source and a load. The circuit interrupter includes: separable contacts; an actuator coupled to the separable contacts and structured to open or close the separable contacts; a current sensor structured to sense current flowing through the circuit interrupter to the load; a communication module communicatively coupled to at least one of a cloud server and a user device and structured to transmit and receive data; and a controller coupled to the sensor, the actuator, and the communication module, the controller comprising at least one of a fault detector and a look-up table, the fault detector structured to detect and classify a fault, the look-up table comprising at least reference data associated with previous normal cycles, the reference data including at least power factors, closing angle ranges and fault classification categories.

A circuit interrupter is structured to electrically connect between a power source and a load. The circuit interrupter includes: separable contacts; an actuator coupled to the separable contacts and structured to open or close the separable contacts; a current sensor structured to sense current flowing through the circuit interrupter to the load; a communication module communicatively coupled to at least one of a cloud server and a user device and structured to transmit and receive data; and a controller coupled to the sensor, the actuator, and the communication module, the controller comprising at least one of a fault detector and a look-up table, the fault detector structured to detect and classify a fault, the look-up table comprising at least reference data associated with previous normal cycles, the reference data including at least power factors, closing angle ranges and fault classification categories.

An apparatus and method for sensing a leakage current along a primary conductor are provided. A first fault detection module is deployed at a first location along the primary conductor and a second driver module is deployed at a second location along the conductor, where the conductor passes through current sensors at each of the modules. The modules are further linked by a safety cable, which also passes through the current sensors. The driver module drives a compensation current in the safety cable to drive the net current passing through the driver current sensor to zero. The fault sensing module senses the net current passing through its current sensor. When the sensed current deviates significantly from zero, the fault sensing module generates a leakage current indication signifying a potential ground fault between the two modules.

A first sense resistor is connected between a fourth terminal of a power source potential of a high-potential region and a first terminal of a ground potential. A second sense resistor is connected between a third terminal of a reference potential of the high-potential region and the first terminal. A comparator is disposed in a low-potential region and uses the ground potential as a reference potential for operation. The comparator compares a voltage between an intermediate potential point of the first sense resistor and an intermediate potential point of the second sense resistor with a predetermined reference voltage. The output of the comparator is input through a control circuit and a level shift circuit to a high-side drive circuit driving an upper-arm IGBT. The output of the comparator is input to a driver circuit driving a lower-arm IGBT.