An arc-like radio frequency (RF) noise detector device is configured to detect and display RF noise on a residential circuit branch that cause or contribute to an arc fault circuit interrupter (AFCI) circuit breaker tripping. It includes a power cord with a plug to connect to a receptacle on a branch circuit of the AFCI circuit breaker to detect RF noise. It further includes a RF noise coupling circuit to receive power from a power entry module and coupled to an Application Specific Integrated Circuit (ASIC) to generate a Received Signal Strength Indicator (RSSI) signal from the detected RF noise. It further includes a power supply, a signal display device configured to receive and display the RSSI signal on a display screen to determine nature of a breaker trip event or likelihood of the breaker trip event and a battery to power the signal display device.

An electronic protection switch includes first and second network terminals and two semiconductor switches of same kind. Each semiconductor switch is formed by an IGBT semiconductor switch and includes a switching element and a diode which is arranged antiparallel to the switching element. A first of the two semiconductor switches is arranged without a semiconductor series connection between a positive potential terminal of the first network terminal and a positive potential terminal of the second network terminal. A second of the two semiconductor switches is arranged without a semiconductor series connection between a negative potential terminal of the first network terminal and a negative potential terminal of the second network terminal. The switching element of each semiconductor switch is arranged so as to be able to conduct and switch off a current from the first network terminal to the second network terminal.

An electronic protection switch includes first and second network terminals and two semiconductor switches of same kind. Each semiconductor switch is formed by an IGBT semiconductor switch and includes a switching element and a diode which is arranged antiparallel to the switching element. A first of the two semiconductor switches is arranged without a semiconductor series connection between a positive potential terminal of the first network terminal and a positive potential terminal of the second network terminal. A second of the two semiconductor switches is arranged without a semiconductor series connection between a negative potential terminal of the first network terminal and a negative potential terminal of the second network terminal. The switching element of each semiconductor switch is arranged so as to be able to conduct and switch off a current from the first network terminal to the second network terminal.

A grounded neutral fault detector that includes induction circuits and a controller is provided. The controller is configured to determine a frequency of a test signal by measuring load noise based on a first leakage signal corresponding to a first current imbalance between the line conductor and the neutral conductor for the load without the test signal being injected, analyzing a frequency spectrum of the load noise, and selecting the frequency of the test signal. The controller is further configured to inject the test signal at the selected frequency to the neutral conductor, measure impedance of a current loop formed by a potential grounded neutral fault based on a second leakage signal corresponding to a second current imbalance with the test signal being injected, and determine a grounded neutral fault.

A power supply control apparatus includes: a first system configured to supply electric power of a first power supply to a first load; a second system configured to supply electric power of a second power supply to a second load; an inter-system switch capable of connecting the first system to the second system and disconnecting the first system from the second system; a battery switch capable of connecting the second power supply to the second system and disconnecting the second power supply from the second system; a primary ground fault detection unit configured to cut off the inter-system switch and conduct the battery switch when a ground fault of the first system or the second system is detected by the primary ground fault detection unit; a secondary ground fault detection unit as defined herein; and a failure determination unit as defined herein.

A power supply control apparatus includes: a first system configured to supply electric power of a first power supply to a first load; a second system configured to supply electric power of a second power supply to a second load; an inter-system switch capable of connecting the first system to the second system and disconnecting the first system from the second system; a battery switch capable of connecting the second power supply to the second system and disconnecting the second power supply from the second system; a primary ground fault detection unit configured to cut off the inter-system switch and conduct the battery switch when a ground fault of the first system or the second system is detected by the primary ground fault detection unit; a secondary ground fault detection unit as defined herein; and a failure determination unit as defined herein.

A power supply control apparatus includes: a first system configured to supply electric power of a first power supply to a first load; a second system configured to supply electric power of a second power supply to a second load; an inter-system switch provided in a connection path that connects the first system to the second system, and capable of connecting the first system to the second system and disconnecting the first system from the second system; a primary ground fault detection unit configured to cut off the inter-system switch when a ground fault of the first system or the second system is detected by the primary ground fault detection unit; a secondary ground fault detection unit as defined herein; and a mask processing unit as defined herein.

An auto recovery circuit breaker (ARCB) device is disclosed that may include a step-down transformer which may provide a low voltage AC test signal to detect a fault in a phase line or neutral of an electric circuit. A first current transformer (CT) is positioned on the first line, and a second CT is positioned on the second line. Each of the first CT and the second CT may sense a current flowing through the electric circuit, and detect an earth leakage through the electric circuit. A microcontroller is configured to: monitor the analog signal in the circuit, detect earth leakage before powering ON the circuit, detect output short before power ON, and upon detection of a fault removal in the electrical circuit, turn ON a relay. Once turned ON, the ARCB device may continue test by sensing the CT’s provided in the phase and neutral lines.

An auto recovery circuit breaker (ARCB) device is disclosed that may include a step-down transformer which may provide a low voltage AC test signal to detect a fault in a phase line or neutral of an electric circuit. A first current transformer (CT) is positioned on the first line, and a second CT is positioned on the second line. Each of the first CT and the second CT may sense a current flowing through the electric circuit, and detect an earth leakage through the electric circuit. A microcontroller is configured to: monitor the analog signal in the circuit, detect earth leakage before powering ON the circuit, detect output short before power ON, and upon detection of a fault removal in the electrical circuit, turn ON a relay. Once turned ON, the ARCB device may continue test by sensing the CT’s provided in the phase and neutral lines.

A vehicle power supply device converts power from high voltage to low voltage by selectively connecting a predetermined power storage element group to a low voltage electric load from a high voltage power supply formed by connecting power storage elements in series. A leakage resistance from the high voltage power supply to the ground is measured when the high voltage circuit is cut by the cutoff means placed between the high voltage power supply and the high-voltage load device. When the value less than a predetermined value, the connection between the high voltage power supply and the low-voltage load device is interrupted, so that electric shock is prevented.