An apparatus, system and method of controlling the supply of DC current from a power source to an electrical load provides for a protective circuit that senses the characteristics of the connected load prior to permitting the enablement of a switch connecting the supply and the load. A voltage arising from applying a constant current to the load during a time period is compared with a predetermined threshold determined by the intended capacity of the switch so that, when closed, the current through the switch is compatible with the switch. The protective circuit may be used in conjunction with semiconductor switches, electromechanical contactors or relays. A plurality of such devices may be incorporated in an enclosure and controlled by logic so as to manage the supply of power from a power source to a plurality of electrical loads having differing power requirements.

An electronic power distribution arrangement is disclosed which includes an electrical line for supplying power to a capacitive load; a first electronic switch for fusing the capacitive load; a second electronic switch for precharging the capacitive load prior to switching through the first electronic switch; a resistor connected in series with the second switchable current path of the second electronic switch, the series connection being connected in parallel with the first switchable current path of the first electronic switch; and a controller. The controller is adapted to turn on the second electronic switch to precharge the capacitive load before turning on the first electronic switch to supply power to the capacitive load, and to turn on the first electronic switch only when a voltage across the resistor reaches a threshold value.

In a method for detecting a motor phase fault of a motor arrangement, the motor phases of which are connected to a drive circuit having a DC voltage intermediate circuit and an inverter. A motor phase voltage at at least one of the motor phases with respect to a reference potential is captured while the inverter is switched off; and a voltage profile of the captured motor phase voltage is used to determine whether there is a motor phase fault on one of the motor phases of the motor arrangement.

The present invention discloses a self-test leakage protector with a timing function, comprising a leakage protection module, a timer module, a DC power supply module, and a DC power supply module control switch, wherein the DC power supply module control switch is connected between the DC power supply module and the leakage protection module, or between input AC power and the DC power supply module that supplies power to the leakage protection module, and is in an off state under a standby condition; according to a timing function requirement, the timer sends a signal of turning off or turning on the DC control switch; and when the turning-on signal is sent, the switch is closed, such that the leakage protection module is powered on for power-on reset, followed by a self-test of a leakage function, and if the self-test is passed, power is supplied to a load, and the self-test is carried out every time before power is supplied to the load. In the invention, the timing function of the timer is integrated in the self-test leakage protector capable of self testing, so the leakage protector is a separate product having a timing function with high safety, low standby power consumption and a low cost.

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.

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 safety device capable of being connected between a circuit breaker device and an electric installation powered by an electric grid providing three-phase current having a first associated frequency, using a line for conveying electric current including three phase conductors, a neutral conductor and a protection conductor. The safety device makes it possible to verify at least one electric safety condition following a cut off of electric power of the electric installation by the circuit breaker device. The safety device comprises circuitry or a processor configured to verify presence of a residual voltage above a predetermined safety threshold on at least one of the conductors, and verify isolation between a tested pair of conductors, among the phase conductors. The safety device can be used to perform an associated safety verification method.

A motor drive device includes a power source unit rectifying AC voltage to DC voltage and to smooth the DC voltage by a capacitor, a motor drive amplification, a power source voltage measurement unit, an insulation resistance deterioration detection unit having a contact unit connecting one end of the capacitor to the ground and a current detection unit provided between the other end of the capacitor and a motor coil, and detecting a deterioration in an insulation resistance of the motor based on a detected signal obtained from a closed circuit formed by the contact unit, the capacitor, the motor coil, and the ground by using the current detection unit, and a failure detection unit detecting a failure in the insulation resistance deterioration detection unit based on the detected signal in the insulation resistance deterioration detection unit and a voltage value measured by the power source voltage measurement unit.

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 fail-safe operating method for a decentralized power generation plant DG includes determining a leakage capacitance of a generator of the DG before connecting the DG. The method also includes comparing the determined leakage capacitance with a predetermined first limit value, and connecting the DG to a grid only if the determined leakage capacitance is smaller than the predetermined first limit value. A decentralized power generation plant is configured to perform the method.