A device for controlling a pre-charge current generated when electrically connecting a first terminal and a second terminal, according to one embodiment of the present invention, may comprise: a switch for controlling a magnitude of a current flowing between the first terminal and the second terminal; a first resistor for generating a base voltage of a first transistor in proportion to a magnitude of the pre-charge current flowing between the first terminal and the second terminal; the first transistor for limiting the magnitude of the pre-charge current when a voltage generated by the first resistor is equal to or greater than a predetermined threshold voltage; a photocoupler for receiving, in a state insulated from a first power source, an optical signal from the first power source and supplying power; a capacitor charged by the power supplied by the photocoupler; a second transistor for controlling the magnitude of the pre-charge current on the basis of a charging voltage of the capacitor; and a second resistor for controlling an operating time of the second transistor along with the capacitor.

Systems and methods for fault detection and protection in electric power systems that evaluates electromagnetic transients caused by faults. A fault can be detected using sampled data from a first monitored point in the power system. Detection of fault transients and associated characteristics, including transient direction, can also be extracted through evaluation of sample data from other monitored points in the power system. A monitoring device can evaluate whether to trip a switching device in response to the detection of the fault and based on confirmation of an indication of detection of fault transients at the other monitored points of the power system. The determination of whether to trip or activate the switching device can also be based on other factors, including the timing of receipt of an indication of the detection of the fault transients and/or an evaluation of the characteristics of the detected transients.

An eFuse for use in high voltage applications is disclosed. In one embodiment, an apparatus includes a solid-state switch having source and drain terminals connected to switch a load current from a high voltage source through a high voltage load. The apparatus also includes a sense circuit that senses a voltage between the switch source and drain terminals and turns off the switch when the voltage exceeds a selected voltage level.

A system for controlling inrush current between a power source and a load includes an output capacitor coupled in parallel with the load, and a transistor having a gate, a collector configured to be coupled to the power source, and an emitter configured to be coupled to the load. The system also includes a supply resistor configured to be electrically coupled between the power source and the load and to provide a resistor charging current from the power source to the output capacitor to charge the output capacitor in response to initial power being provided by the power source. The system also includes a gate resistor having a first terminal coupled to the gate of the transistor to cause the transistor to operate in a linear mode in response to the initial power being provided by the power source to increase a speed of charging the output capacitor.

A power supply apparatus including a protection circuit and a power conversion circuit is provided. The protection circuit includes a control circuit, an auxiliary capacitor, and a switching circuit. The control circuit receives an AC voltage from an AC power source and generates a pulsating voltage and a control signal accordingly. The auxiliary capacitor receives the pulsating voltage and provides a first voltage accordingly. The switching circuit is coupled to the auxiliary capacitor to receive the first voltage and coupled to the control circuit to receive the control signal. The switching circuit transmits the first voltage to the power conversion circuit in response to the control signal. The power conversion circuit converts the first voltage to an output voltage. When the switching circuit is switched to an on state in response to the control signal, the auxiliary capacitor reduces an input inrush current from the AC power source.

A method for operating an electronic circuit breaker having a semiconductor switch that is connected between a voltage input and a load output and that is driven as a function of the output voltage sensed at the load output during the switching on and/or cutting in of a capacitive load, wherein the output voltage is compared with a stored voltage threshold value, wherein when the voltage threshold value is reached or negatively exceeded, a current limit, to which a load current carried by the semiconductor switch is limited, is increased from a nominal value to a first step value increased therefrom, wherein the current limit is reduced stepwise from the first step value to the original nominal value, and wherein the semiconductor switch is opened if the output voltage does not reach the voltage threshold during a triggering time after the stepwise reduction of the current limit.

A method and system for controlling a three-phase drive connected to a three phase power source. The method includes connecting a converter to transfer power from the power source to a first direct current (DC) bus, where the converter and the first DC bus each have a neutral common point (NCP). Connecting a second DC bus to the first DC bus and configuring an inverter connected to the second DC bus to draw power from the second DC bus to provide a plurality of motor signals, the inverter having an inverter NCP. The method also includes connecting a neutral point selection device to the first DC bus NCP and selectively connecting to the converter NCP or the inverter NCP, the bus selection device configured to disconnect the converter NCP or the inverter NCP from the first DC bus NCP under selected conditions.

A power supply control apparatus that includes a switching circuit that turns ON or OFF a switch provided at a point along a wire, wherein power supply via the wire is controlled by switching with the switching circuit; a current output circuit configured to output a current whose current value increases as a current value of a current flowing through the wire increases; a resistance circuit through which the current that the current output circuit outputs flows, wherein the resistance circuit includes: a first resistor; and a series circuit of a second resistor and a capacitor that is connected in parallel to the first resistor; and a voltage applying circuit configured to, if an end-to-end voltage value across the resistance circuit becomes higher than or equal to a predetermined voltage value, apply a voltage whose value is higher than the predetermined voltage value.

Systems and methods for fault detection and protection in electric power systems that evaluates electromagnetic transients caused by faults. A fault can be detected using sampled data from a first monitored point in the power system. Detection of fault transients and associated characteristics, including transient direction, can also be extracted through evaluation of sample data from other monitored points in the power system. A monitoring device can evaluate whether to trip a switching device in response to the detection of the fault and based on confirmation of an indication of detection of fault transients at the other monitored points of the power system. The determination of whether to trip or activate the switching device can also be based on other factors, including the timing of receipt of an indication of the detection of the fault transients and/or an evaluation of the characteristics of the detected transients.

A DC high-voltage electrical installation comprises a switching device for switching an electric current in the main circuit, and a method for controlling the closure of a switching device in such an installation. The installation includes a controlled variable resistor system making it possible to modify the resistance value of the resistor system seen by the current flowing through the main electrical circuit. The resistance value takes at least three distinct values: high, a lower value, and at least one nonzero intermediate value comprised between the high value and the low value. The installation includes a coordination device making it possible to control switching times of the resistance values of the resistor system.