Abstract: In one embodiment, a method includes transmitting power in a power and data distribution system comprising at least two pairs of wires, negotiating a power level between Power Sourcing Equipment (PSE) and a Powered Device (PD) in the power and data distribution system, transmitting the power at a power level greater than 100 watts, periodically checking each of the wires for a fault, and checking for an electrical imbalance at the wires.

Abstract: A system includes a sensor circuit configured to sense a parameter of a power system having an operating voltage greater than a voltage rating of the sensor circuit, an optical communications circuit configured to receive a sensor signal from the sensor circuit and to generate an optical communications signal therefrom, and an optical power supply circuit configured to receive an optical input, to generate electrical power from the received optical input and to supply the generated electrical power to the sensor circuit and the optical communications circuit. A driver circuit may be configured to generate a first control signal applied to a control terminal of the power semiconductor switch, and the optical power supply circuit may be configured to supply the generated electrical power to the sensor circuit, the optical communications circuit and the driver circuit.

Abstract: A driving apparatus includes: a driving section configured to drive a control terminal of a semiconductor device according to a control signal input from an outside, the semiconductor device including a first main terminal, a second main terminal, and the control terminal that is configured to control a connection state between the first main terminal and the second main terminal that are connected in parallel with a snubber; and a drive control section configured to lower a drive capability of the driving section during a period in which an inter-main-terminal voltage between the first main terminal and the second main terminal changes by a predetermined reference voltage difference owing to switching of the semiconductor device, compared with other at least some periods.

Abstract: An apparatus comprises an energy transfer device that operates one or more input switches of an input side of an electrical isolation device to transfer energy through the isolation device to an output side of the electrical isolation device for activating a switch. The apparatus comprises a voltage conversion device that converts the energy from an input voltage of the input side to an output voltage to control the switch when the energy transfer is active. The apparatus comprises a passive turn off device that passively deactivates the switch when the energy transfer is inactive. The passive turn off device is disabled from deactivating the switch when the energy transfer is active.

Abstract: Various embodiments include a switching device for disconnecting a current path in a DC supply system, said current path comprising inductances at the source end and the load end, the switching device comprising: two series-connected switching modules; wherein each of the series-connected switching modules comprises a controllable semiconductor switching element and a series circuit; the series circuit including a resistor and a capacitor connected in parallel to the controllable semiconductor switching element.

Abstract: A method and apparatus for identifying an air-conditioning circuit, and an air conditioner.

Abstract: A power distribution device includes an input, an output, a power switch controller, and a voltage isolation device. The power distribution device includes, and is designed to provide power to, for example, non-radiation-tolerant or non-radiation hardened components for use in low Earth orbit (LEO) missions. The input is configured to receive power from a power source. The output is configured to provide the power to an electrical load. The power switch controller is configured to selectively operate the power distribution device in a first mode responsive to a first event, and to selectively operate the power distribution device in a second mode responsive to a second event. The voltage isolation device includes a plurality of switches configured, in the first mode, to pass the power between the input and the output, and, in the second mode, to interrupt the passage of the power between the input and the output.

Abstract: A portable information handling system selectively accepts power transferred from an external device through a port, such as USB Type C port, with one of a first or second power configuration. The first power configuration accepts power regulated by a charger of an external device and routed directly to a system bus and battery of the portable information handling system. The second power configuration accepts power regulated by an internal charger of the portable information handling system, such as a narrow voltage direct current charger.

Abstract: An apparatus may include a first switch leg and a controller. The first switch leg may include a first switch and a second switch. The second switch may be connected in series to the first switch. For a first half of a switching cycle, the controller may control the first switch and the second switch to be OFF. For a second half of the switching cycle, the controller may control the first switch to alternate between being ON and being OFF and to control the second switch to be ON.

Abstract: A circuit comprises an output connector connectable to a load. A relay selectively connects the output connector to an AC power source. The relay is responsive to a disabling signal to disconnect the output connector from the AC power source. A sensor senses a level of power delivered to the load via the output connector. A detector emits a first fault signal when the sensed power level exceeds a fixed power limit. A latch maintains the first fault signal until it receives a rearm signal. A controller emits a second fault signal when the sensed power level exceeds a configurable power threshold, receives a user command to rearm the circuit, and in response to receiving the user command, emits the rearm signal and ceases the emission of the second fault signal. A logic combiner generates the disabling signal when it receives one of the first and second fault signals.

Abstract: A packet forwarding network may include spine and leaf switches that forward network traffic between end hosts that are coupled to the packet forwarding network. A controller may control the switches in the forwarding network to implement desired forwarding paths. The packet forwarding network may additionally include access switches that are directly connected to edge switches to form access switch groups. The access switches may also be controlled by the controller. End hosts may be coupled to access switches as well as leaf switches to extend the reach of the packet forwarding network. Additionally, the access switches may include access-leaf switches and access-edge switches to improve network routing capabilities and network flexibility.

Abstract: The ECU includes first and second power terminals, first and second voltage limiting elements, first and second diodes, and a power supply IC. A voltage is applied to the first power terminal from a battery, and a voltage is applied to the second power terminal from the battery via a start switch. The first voltage limiting element is provided between the first power terminal and an input terminal of the power supply IC. The cathode of the first diode is connected to the input terminal of the power supply IC. The second voltage limiting element is provided between the second power terminal and the anode of the first diode. The cathode of the second diode is connected to the anode of the first diode, and the anode is grounded. A limit voltage of the first voltage limiting element is greater than a limit voltage of the second voltage limiting element.

Abstract: This application relates to switch arrangements, in particular switch arrangements suitable for switchable connecting nodes of audio driving circuitry (100) that may, in use, experience a signal swing depending on an output audio driving signal (VD). A switch arrangement (300) comprises first and second transistors (301 and 302) of the same polarity type connected in series between the first and second nodes, with a third transistor (303) connected between a defined voltage (VS) and an intermediate node (N3) between the first and second transistors. The first transistor (301) has a drain connection to the first node (N1) and a source connection to the intermediate node (N3). The second transistor (302) has a drain connection to the second node (N2) and a source connection to the intermediate node (N3).

Abstract: In a furniture supported power control arrangement and method, power is controlled selectively from one of two furniture locations in the arrangement. A three-way circuit is comprised of low-voltage wiring connecting a first double-throw electric switch carried at a first furniture location for selective manual actuation, and a second double-throw electric switch carried at a second furniture location for selective manual actuation. A low-voltage driver supplies low-voltage power to the three-way circuit, and a low-voltage room lighting system is connected to the three-way circuit, whereby low-voltage power is directed to or disconnected from the room lighting system as controlled selectively by actuation of either one of the first and second double-throw electric switches.

Abstract: A converter for controlling power flows between three electricity networks with different operating voltages. The converter includes, in one implementation, three terminals and two converter cells. Each of the three terminals are configured to electrically contact-connect one of the three electricity networks. Each of the two converter cells includes a transformer having three converter cells. One of the terminals is connected to a series circuit of the converter cells. Another of the terminals is connected to a parallel circuit of the converter cells.

Abstract: A method and an apparatus of estimating power using a plurality of branch load circuits associated with a mains three phase power supply, comprises: a voltage sensor (303) coupled to a mains power supply; a non-intrusive magnetic flux sensor array (304) coupled to a plurality of branch load circuits (305), the branch load circuits (305) coupled to the main power supply; and a computing device coupled to the voltage sensor (303) and the non-intrusive magnetic flux sensor array (304), in which a set of current-flux conversion values are to be stored in memory of the computing device.

Abstract: A combined direct current circuit breaker includes a transfer branch, an energy absorption branch, at least two primary branches and at least two secondary branches; the transfer branch is connected in parallel with the energy absorption branch; the primary branches are in one-to-one correspondence with the second branches; the primary branches are connected with direct current outgoing lines of a direct current busbar in a high-voltage direct current power transmission system; the secondary branches are connected in series with the transfer branches and then connected in parallel with two ends of the primary branches corresponding to the secondary branches.

Abstract: A head-mounted display system includes a head-mounted display gear, a host, and two USB Type-C transmission lines. The two USB Type-C transmission lines are coupled between the head-mounted display gear and the host for transmitting power, data and video streams.

Abstract: Embodiments of the present disclosure relate generally to systems and methods for providing improved aircraft fuel cell systems. In one embodiment, the system provides separate zones, maintaining various equipment components in separate controlled hydrogen concentration zones. In one embodiment, the fuel cell system provided may be simpler such that it functions without a power converter and autonomous such that it functions without need for power from any aircraft supply.

Abstract: A system, method and apparatus for providing ancillary services to a power grid using a power consumption component at a customer premises. The apparatus may control a load with discrete, finite states of power or an on/off load at a customer premises using a controller. The controller may comprise a processor, which may be configured to receive a regulation signal associated with an ancillary service for the power grid; determine whether to modify a state of power of the power consumption component based on a probability function, local measurement at the premises, and the received regulation signal; and based at least in part on a determination to modify the state of power of the power consumption component, modify the state of power of the power consumption component. The system may be distributed, with different controllers at different customer premises independently making power state decisions.

Abstract: [Problem] To suppress current flowing to a contact of a relay when grounding a device to be grounded by connecting the contact of the relay, and to suppress arc discharge between relay contacts when the grounding state of the device to be grounded is released by disconnecting the relay contact. [Solution] A grounding circuit equipped with: a first relay contact connected to a device to be grounded; a resistor that is connected between the first relay contact and an earth, and that suppresses current flowing to the first relay contact when the contact of the first relay is closed; and a second relay contact that is connected in parallel with the resistor, and that is closed before the first relay contact is opened when the grounding state of the device to be grounded is released.

Abstract: Provided is a digital circuit (30) that comprises: a switching circuit (31) having first transistors (32, 33) supplied with power supply potentials (VDD, VSS); correcting circuits (34, 36) connected between an input terminal (IN) inputted with an input signal and control terminals (gates) of the first transistors; capacitors (C2, C3) connected between the control terminals and the input terminal; diode-connected second transistors (35, 37) that are provided between nodes (N5, N6) between the capacitors and the control terminals and the power supply potentials and have the substantially same threshold voltage as the first transistors; and switches (SW2, SW3) connected in series with the second transistors.

Abstract: The present invention relates to an electrical circuit arrangement with an active discharge circuit including at least one electrical switching element, by means of which the circuit arrangement can be discharged in controlled manner. The circuit arrangement includes a RC snubber element with capacitor and resistor for damping voltage or current peaks in the circuit arrangement, wherein the electrical switching element is integrated in the RC snubber element and connected in parallel to the capacitor of the RC snubber. This enables the discharge circuit to be designed in a manner that is economical in terms of space and cost. The discharge circuit uses the heat sink for the RC snubber element and therefore does not need any additional heat dissipation systems.

Abstract: A direct-current switching device for interrupting an electric direct current flowing along a medium or high-voltage current path, includes an electric circuit assembly having a mechanical switching device to be switched in the medium or high-voltage current path. The electric circuit assembly further has an LC circuit with an inductive component in order to force a current zero crossing in the mechanical switching device connected in the medium or high-voltage current path, a capacitive component for forming a resonant circuit being closed by the switching device, and a switchable semiconductor component for generating an excitation frequency exciting the resonant circuit. The switchable semiconductor component is disposed in the electric circuit assembly such that the semiconductor component constantly lies outside of the medium or high-voltage current path when the mechanical switching device is connected in the medium or high-voltage current path.

Abstract: A direct current switch-off device comprises an on-state current branch circuit and a current commutating and breaking unit which are connected in parallel. The on-state current branch circuit has a mechanical switch (S) and a current transfer module which are connected in series. The current commutating and breaking unit comprises a bridge-type branch circuit and a current-breaking branch circuit. The current-breaking branch circuit and two bridge arms of the bridge-type branch circuit are connected in parallel. The current-breaking branch circuit comprises a nonlinear resistor (RI) and a valve group consisting of fully-controlled devices connected in series. The nonlinear resistor (RI) and the valve group are connected in parallel. Two ends of each fully-controlled device in the valve group are connected in parallel with a buffering and reclosing circuit.

Abstract: A high power switching circuit suitable for injection of high currents, typically several tens of Amperes, at high drive voltages of up to 5-10 kV, is provided using a combination of electromechanical and semiconductor switching elements that, while providing switchable polarity, substantially bypasses semiconductor switching element(s) during a substantial portion of current injection duty cycles. In this way, thermal heating of switching elements can be reduced/managed in a way that improves long term reliability of geophysical survey equipment. In addition, circuit protections can be provided to address backflow currents generated upon collapse of electromagnetic fields in inductive loads, such as is typical in geophysical surveys.

Abstract: A power electronics arrangement may comprise a power supply, a controller configured to receive a power from the power supply and generate an output signal, a waveguide, a receiver, filter, and converter (RFC) configured to receive the output signal via the waveguide, the RFC configured to generate a switching signal from the output signal, and a power switching device (PSD) configured to receive the switching signal from the RFC, wherein the controller transmits the output signal to the RFC through the waveguide via a transponder, the waveguide is coupled between the transponder and the RFC, and the PSD is galvanically isolated from the power supply.

Abstract: Direct current (“DC”) power such as from solar panels is used by home appliances directly without conversion to AC. The large direct current spark problem is alleviated by interrupting the DC current at periodicities of at least 120 hertz and typically 99 percent duty cycle. This interrupted DC power is less harmful to switches and circuit breakers than equivalent AC power. Furthermore, the interrupted DC power is used with greater efficiency by computers, and can be used to power a wide range of appliances. Exceptions are inductive appliances, which are detected and treated differently, by a smart power receptacle embodiment. These embodiments provide a very low cost and efficient path to an all DC electric power future.

Abstract: There is provided an electrical assembly for use in an electrical system. The electrical assembly comprises a DC path. The DC path includes: a DC power transmission medium; and a current commutation device, the current commutation device including a switching element and an energy absorbing element, the switching element arranged to permit a current flowing, in use, through the DC path to flow through the switching element and at the same time bypass the energy absorbing element, wherein the electrical assembly further includes a control unit programmed to selectively control the switching of the switching element to commutate the current directly from the switching element to the energy absorbing element in order to increase the resultant voltage drop caused by the flow of direct current through the DC path in which the current commutation device is connected and thereby oppose the flow of the current through the DC path.

Abstract: A circuit arrangement for a photovoltaic inverter includes two bus lines, input terminals for connecting at least one photovoltaic generator to the bus lines, respectively, and at least one DC/AC converter connected to the bus lines. The circuit arrangement further includes a disconnector between each DC/AC converter and the bus lines, respectively, and at least one short-circuit path for short-circuiting a voltage between the bus lines, wherein a short-circuit switch is arranged in the short-circuit path, wherein the at least one short-circuit path runs between the bus lines upstream of all disconnectors between the input terminals and the disconnectors, and wherein the short-circuit switch in the at least one short-circuit path between the bus lines is connected in series with a fuse.

Abstract: A device for limiting the inrush current component of a current provided by a supply to a load, the device including an impedance arranged between the supply and the load, a switch arranged to divert the current from the impedance, an inrush period timer connected to the supply and arranged to activate the switch after expiry of an inrush time period, the inrush time period being a time period beginning upon the supply becoming active such that current is available to be provided by the supply to the load and a reset circuit connected to the supply and the inrush period timer, the reset circuit arranged to deactivate the switch and reset the inrush period timer in response to the supply becoming inactive such that no current is available to be provided by the supply to the load.

Abstract: The subject matter of this specification can be embodied in, among other things, an identification system includes a first component having a first resistor and a second resistor, a second component having a sensor configured to sense a voltage difference between a first bus and a second bus and a selector signal output port configured to provide a first selector signal and a second selector signal, and a third component having a switching network configured to electrically connect the second bus to the first bus across one or both of the first resistor and the second resistor in response to the first selector signal, and electrically connect the second bus to the first bus across a different one of the first resistor or the second resistor in response to the second selector signal.

Abstract: This power feed line switching circuit for switching connection states among a plurality of power feed lines has a plurality of switching circuits, and a variable resistance unit. The switching circuits switch the connection states among the power feed lines. The variable resistance unit is disposed on the connecting paths among the power feed lines before and after the switching, and the resistance values thereof change in conjunction with operations of the switching circuits.

Abstract: A direct-current switching device switches direct currents, in particular direct currents in the kiloampere range. The switching device contains a switching unit, a resonant circuit, and an overvoltage arrester. During the switching off of the switching unit, the resonant circuit produces an oscillating resonant current, which is superposed with the direct current still flowing through the switching unit during the switching off of the switching unit. Accordingly, connected in series with the switching unit, hereinafter referred to as the first switching unit, is a second switching unit, the switching behavior of which differs from the switching behavior of the first switching unit, and the resonant circuit and the arrester lie electrically in parallel with the series connection.

Abstract: Embodiments are directed to a lightning protection circuit configured for use in a solid state power controller (SSPC) having at least one feed line and a plurality of load lines. The lightning protection circuit includes a shared transient voltage suppressor and a transient isolator communicatively coupled to the shared transient voltage suppressor. The transient isolator is configured to be communicatively coupled to the at least one feed line and the plurality of load lines. When the transient isolator is communicatively coupled to and shared by the at least one feed line and the plurality of load lines, energy above a threshold on any one of the at least one feed line and the plurality of load lines is dissipated through the shared transient voltage suppressor. A single built-in-test (BIT) circuit is provided to detect dormant failures of the shared transient voltage suppressor.

Abstract: Provided is a data driver for a display panel. The data driver includes an auxiliary power generating unit and an auxiliary power output unit. The auxiliary power generating unit may generate an auxiliary power. The auxiliary power output unit may supply the auxiliary power to the display panel when the display panel is driven in a power saving mode under the control of the auxiliary power generating unit. The auxiliary power output unit may include a first transistor configured to output the auxiliary power output from the auxiliary power generating unit, a diode configured to output the auxiliary power output from the first transistor, and a second transistor connected to the diode in parallel and configured to output the auxiliary power together with the diode.

Abstract: A high power switching circuit suitable for injection of high currents, typically several tens of Amperes, at high drive voltages of up to 5-10 kV, is provided using a combination of electromechanical and semiconductor switching elements that, while providing switchable polarity, substantially bypasses semiconductor switching element(s) during a substantial portion of current injection duty cycles. In this way, thermal heating of switching elements can be reduced/managed in a way that improves long term reliability of geophysical survey equipment. In addition, circuit protections can be provided to address backflow currents generated upon collapse of electromagnetic fields in inductive loads, such as is typical in geophysical surveys.

Abstract: A first bidirectional switch is electrically connected between a first connection point which is a connection point of a first switching element and a second switching element and a second connection point which is a connection point of a seventh switching element and an eighth switching element. A second bidirectional switch is electrically connected between a third connection point which is a connection point of a third switching element and a fourth switching element and a fourth connection point which is a connection point of a fifth switching element and a sixth switching element. A power-converting device is configured to generate an output voltage between a first output point and a second output point.

Abstract: A parking management system and methods of operation are disclosed. In one variation, a computer-implemented method comprises receiving positional data concerning a listing location from a listing client device; establishing a radius boundary based on the positional data; filtering one or more databases using the radius boundary to determine an amount of parking spaces listed and the amount of parking spaces reserved within a preset time period; calculating a location-specific transaction rate using the amount of parking spaces listed, the amount of parking spaces reserved, and the preset time period; determining a recommended listing price based on the location-specific transaction rate; and transmitting the recommended listing price to the listing client device.

Abstract: Communicatively coupling multiple networking-enabled electronic devices to a local ring communication network enables remote monitoring and maintenance of the networked electronic devices with a single network gateway device per local network. The devices are coupled to the ring network in series through a loop cable assembly. The loop cable assembly enables forwarding of data received at a particular electronic device from another electronic device separately coupled to the loop cable assembly, via a portion of the loop cable assembly, to the gateway device, via another portion of the loop cable assembly. The loop cable assembly can include multiple network cables and dongles. The loop cable assembly may include a back-pass pathway, where a network terminator device coupled to a network connector at a distal end of the loop cable assembly from the network gateway device reroutes output data back through loop cable assembly towards the network gateway device.

Abstract: Provided is a digital circuit (30) that comprises: a switching circuit (31) having first transistors (32, 33) supplied with power supply potentials (VDD, VSS); correcting circuits (34, 36) connected between an input terminal (IN) inputted with an input signal and control terminals (gates) of the first transistors; capacitors (C2, C3) connected between the control terminals and the input terminal; diode-connected second transistors (35, 37) that are provided between nodes (N5, N6) between the capacitors and the control terminals and the power supply potentials and have the substantially same threshold voltage as the first transistors; and switches (SW2, SW3) connected in series with the second transistors.

Abstract: There is described a method for driving paralleled electronic switches via a drive signal processing circuit (1) connected to respective driver circuits (5A, 5B) associated with said electronic switches (7 A, 7B). During the turn-off intervals of the electronic switch, the driver circuit sends a fault signal to the drive signal processing circuit. During the turn-off intervals of the electronic switch, the driver circuit masks the fault signal coming from the drive circuit of the electronic switch.

Abstract: In a device for monitoring and switching a load circuit, having an input part and an output part, having switching inputs to connect a controller to the input part, having switching outputs to connect at least one load circuit with at least one load to be switched to the output part, having at least one load switch to switch, in particular to switch on and off, the at least one load, having a first fault detection circuit, connected in parallel with the load circuit, to detect faults in the load circuit, and having a second fault detection circuit, connected in series with the load circuit, to detect faults in the load circuit, the input part has an input circuit which converts switching commands of the controller incoming via the switching inputs into switching processes of the load switches. The first and the second fault detection circuit respectively generate intermediate fault signals which are logically linked in a logic circuit to form an overall fault signal.

Abstract: The invention relates to a device for monitoring and switching a load circuit, having an input part and an output part, having switching inputs to connect a controller to the input part, having switching outputs to connect at least one load circuit with at least one load to be switched to the output part, having at least one load switch to switch, in particular to switch on and off, the at least one load, having at least one fault detection circuit to detect a fault in the load circuit and to generate at least a first fault signal in the output part, and having a galvanic isolation stage for galvanically isolated transmission of this first fault signal and/or a second fault signal derived from this first fault signal from the output part to the input part. According to the invention the input part has an input circuit which converts switching commands of the controller incoming via the switching inputs into switching processes of the load switches.

Abstract: An apparatus for breaking a line bidirectional current and a control method therefore. The apparatus comprises a breaking current branch circuit and an on-state current branch circuit, the breaking current branch circuit comprises one nonlinear resistor being connected in parallel to one first power semiconductor device, or one nonlinear resistor being connected in parallel to at least two first power semiconductor devices mutually connected in series; and the on-state current branch circuit comprises at least one bidirectional power semiconductor switch being connected in series to at least one high-speed isolation switch. The apparatus also comprises a bridge-type branch circuit. An apparatus for breaking a line bidirectional current, thereby greatly reducing costs of the apparatus and reducing difficulty in device layout, mounting and wiring of the apparatus on the premise of ensuring a breaking speed that is quick enough and a low loss.

Abstract: Disclosed herein is a polling system, including: a matrix element including individual elements including upper electrodes and lower electrodes, the individual elements being arrayed in plural, the upper electrodes of the individual elements being each connected in series to form upper electrode units which are arrayed in plural and the lower electrodes of the individual elements being each connected in series to form lower electrode units which are arrayed in plural; an upper switch connected to each of the upper electrode units which is arrayed in plural; a lower switch connected to each of the lower electrode units which is arrayed in plural; and a polling unit performing polling to apply voltage to the upper electrodes and the lower electrodes, respectively.

Abstract: According to one embodiment, a magnetizing inrush current suppressing device includes, a first closing unit closes the circuit-breaker at the notable phase by the first phase determined by the first-phase determination unit, a second-phase determination unit determines a second phase at which the notable phase detected by the notable phase detection unit from the three-phase AC voltage measured by the power-supply-side voltage measurement unit becomes a zero point after the first phase determined by the first-phase determination unit, and a second closing unit closes the circuit-breaker at two phases other than the notable phase by the second phase determined by the second-phase determination unit.

Abstract: The present invention relates to an electric power supply system for an aircraft having a transformer-less HVDC architecture, the system including: at least one multiphase engine generator in a star configuration which provides a multiphase alternating (AC) voltage; a converting circuit for converting the multiphase AC voltage into a corresponding direct (DC) voltage for supplying at least one aircraft load; an electric power supply interface for connection with a standardized GPU plug of an external GPU, the electric power supply interface comprising a supply voltage output terminal coupled to a self-contained power source for providing a low voltage control signal for driving a GPU internal switching circuit wherein the power source is decoupled from the AC voltage and DC voltage. The present invention further relates to an aircraft and an airport power supply system.

Abstract: A cascoded power semiconductor circuit has a clamp circuit between the source and gate of a gallium nitride or silicon carbide FET to provide avalanche protection for the cascode MOSFET transistor.

Abstract: A branching unit (1) for an optical telecommunication link (100), the unit comprising a first (2), a second (3) and a third terminal (4) for termination of conductors of respective branch cables in use, a fourth terminal (5) for connection to a sea earth (6) in use, and a circuit (8) comprising a plurality of relays comprising at least a first, a second and a third relay associated to respectively the first, second and third terminal, the circuit being structured for connecting together two terminals out of the first, second and third terminal and for connecting the remaining terminal to the fourth terminal, depending on a sequence of power feeding at the first, second and third terminals, in use, wherein the circuit (8) comprises a sea earth circuit (9) terminated at one end to the fourth terminal and a bidirectional triode thyristor (13) placed along the sea earth circuit, a driving circuit (19) being provided for driving the bidirectional triode thyristor so as to trigger the bidirectional triode thyristor