Abstract: A switching device including a movable contact member. The movable contact member produces an isolating distance and includes an integral semiconductor switching element.

Abstract: A switch gear protection circuit for use in electric vehicles provides parallel circuit pathways for selectively coupling a power source to a capacitive load. A first pathway includes a main switch element that preferably is a high-current contactor or a high-current, low-voltage relay switch. A second pathway, which is in parallel with the first pathway, includes a low-voltage, low-current switch element in series with a circuit breaker element such as a fuse. When it is desirable to open the main switch element in the first pathway, the second pathway is closed. Once the second pathway is closed, the voltage drop across the first pathway is reduced and the first switch element can be opened. The parallel arrangement provides the ability to use low-voltage switch elements, that are relatively inexpensive compared to high-voltage components.

Abstract: Control device for a multiphase electric motor (M) comprising firstly two two-directional static switches (IS1, IS2) each associated with a terminal of a shunt contactor (S) installed in parallel, these switches (IS1, IS2, S) being controlled by a control circuit (C) controlling progressive operation of the motor, characterized in that the shunt contactor (S) is of the four-pole type and is fitted with solid connection parts (6, 7) each connecting two terminals of the said contactor, these connection parts (6, 7) being connected in pairs (L1, L3) to the terminals of the static switches (IS1, IS2) such that each (IS1 or IS2) is connected to two terminals.

Abstract: The device includes two breaking areas formed at each side of a contact bridge carrying main contacts that can be separated from fixed contacts located in the breaking areas and fixed to main conductors. The main conductors each have shaped extensions in the break areas that are configured to cooperate with shaped extensions associated with arc collection parts positioned nearby. The shaping of the extensions and the spacing therebetween encourage a particular direction of arc migration relative to arcs created when the moveable contacts carried by the contact bridge are separated from the fixed contacts. Further, arc migration control is provided in the form of magnetic fields provided in each breaking area. Each arc collection part is connected through a shunt conductor and a single direction of current flow establishing component to make a direct electrical connection to the main conductor associated with the other area.

Abstract: An electronic switch circuit for controlling a main circuit including a power source and a load, the electronic switch circuit including (a) an electromagnetic relay device including an electromagnet and at least two contacts, the electromagnetic relay device being connectable in series to the power source and the load of the main circuit; (b) a controlled semiconductor device being a part of the electronic switch circuit; (c) a semiconductor command circuit being connected to the semiconductor device, the semiconductor command circuit serving for controlling the operation of the controlled semiconductor device; (d) a relay command circuit being connected to the electromagnet of the electromagnetic relay device and to the semiconductor command circuit, the relay command circuit serving for controlling the relay device and the semiconductor command circuit; (e) an overload sensor serving for determining a current load flowing through the main circuit and for reporting the relay command circuit of a current ove

Abstract: A current interrupter circuit includes a primary current path and a secondary current path in parallel with one another and provided between input and output terminals. At least one solid state switch, preferably a power MOSFET, are interposed along the secondary current path. At least one electromagnetic relay has relay contacts for engaging and disengaging the primary path from a power source and from the secondary path. A sequencing circuit provides a first control signal to turn on or maintain on the solid state switches prior to sending a second control signal to open/close the relay contacts, and further provides a third control signal to turn off the solid state switches shortly after the relay contacts are opened, whereby arcing of the contacts is prevented.

Abstract: An overcurrent protection system which will give a rapid response to overcurrents which cause a reduction in the voltage across the load, e.g. a partial or complete short across the load, and which will preserve the trip endurance of a PTC device used in the protection system. The new system maintains the trip endurance of the PTC device by removing the source voltage from the PTC, while still keeping the circuit protection arrangement in a fault state, thereby continuing to protect the load.

Abstract: A device and a method for interrupting very high direct currents (greater than 100,000 amperes) and simultaneously blocking high voltages (greater than 600 volts). The device utilizes a mechanical switch to carry very high currents continuously with low loss and a silicon controlled rectifier (SCR) to bypass the current around the mechanical switch while its contacts are separating. A commutation circuit, connected in parallel with the SCR, turns off the SCR by utilizing a resonant circuit to divert the SCR current after the switch opens.

Abstract: A hybrid power switching device for eliminating mechanical relay arcing. The device reduces mechanical relay contact damage due to arcing and substantially reduces power dissipation by placing a solid state relay in parallel with a mechanical relay. The solid state relay is preferably a semiconductor triac optically coupled to a light emitting diode. The device takes advantage of the inherent lag time (operating time) when a mechanical relay contact switch closes. The device uses only analog components and controls the triac by means of a Schmitt trigger pulse stretcher. The advantages to the present Schmitt trigger include discrete turn off and a narrow hysteresis. A low level control voltage signal operates the mechanical relay and the Schmitt trigger, or optionally a high level control voltage signal in conjunction with a signal inverter.

Abstract: An electrical device for switching an arc to a path parallel to a device to be protected. The electrical device includes double breaking contacts and an arc transfer electrode associated with the parallel path. The parallel path shunts the double breaking contacts and a device to be protected via the arc transfer electrode. The arc transfer electrode is placed in the vicinity of a fixed contact of the double breaking contacts.

Abstract: An objective of this invention is to provide a DC circuit breaking device having functions for transmitting direct currents to an electric power system and interrupting direct currents to the electric power system under abnormal conditions such as grounding and short-circuits, where the DC circuit breaking device can minimize the capacity of a condenser for the commuting circuit while rapidly changing the arc voltage to cause arc currents to be quickly extended and vibrated in order to interrupt direct currents in a short arc time. This DC circuit breaking device includes a main DC circuit breaker for interrupting the transmission of direct currents to an electric power system and a DC circuit breaker that is connected in series to the main DC circuit breaker and which is smaller than the main DC circuit breaker.

Abstract: A plurality of solid-state switches are provided in parallel with a main circuit switch. A main circuit current is detected by a first current detecting device. A current flowing in each of the plurality of solid-state switches is detected by a second current detecting device. Based on the detected currents of the first and second current detecting devices, the main circuit switch is commanded to open and each solid-state switch is commanded to close by a control circuit, when a fault is detected by a fault detecting circuit. At this point of the process when the main circuit switch is opened, when a commutation anomaly is detected by a commutation detecting circuit, the conducting status of each solid-state switch is maintained. When the commutation achieves a normal status, each solid-state switch is interrupted and circuit breaking, at the point the capability of each solid-state switch is exceeded, is prevented.

Abstract: The arc suppression circuit includes an insulated gate bipolar junction transistor (IGBT) connected across the electrical switch contacts to be protected. When the contacts open, the combination of added Miller capacitance and the gate-to-emitter capacitance of the IGBT results in the IGBT turning on. The IGBT is quickly turned off thereafter by a second transistor, which turns on as the voltage across the suppression circuit rises following turn-on of the IGBT. The turning on of the second transistor results in the first power transistor quickly and abruptly turning off so that relatively little of the load energy is dissipated in the power transistor.

Abstract: A hybrid or combination solid state/electromechanical relay circuit combines the advantageous features of solid state and electromechanical relays but avoids their disadvantageous features. An electromechanical relay includes a coil and a pair of contacts which close in response to energization of the relay coil; this pair of contacts being coupled between the load and the ac source. The relay coil is coupled through a switch to a source of dc coil voltage and is also connected to ground. A triac has its first and second main electrodes coupled in parallel to the pair of contacts of the electromechanical relay between the ac source and the load. A capacitor has one lead connected to the first lead of the relay coil and a second lead connected to the gate of the triac. On application of power to the coil, the capacitor charges through the triac, mining it on prior to the coil voltage of the relay reaching its design pick-up voltage. Then during switch dormancy, the coil-energized relay contacts carry the load.

Abstract: An overcurrent protection system which will give a rapid response to overcurrents which cause a reduction in the voltage across the load, e.g. a partial or complete short across the load, and is particularly suitable for protecting circuits against relatively small overcurrents, comprising: a circuit interruption element which, in the operating circuit, is connected in series between the electrical power supply and the electrical load, and which has (1) a closed state which permits the flow of a normal current, I.sub.NORMAL, through the circuit interruption element, and (2) an open state which permits the flow of at most a reduced current, substantially less than I.sub.NORMAL, through the circuit interruption element; a control element which, in the operating circuit, is connected in parallel with the load, and which has (1)(i) an on state, when the voltage across the control element is a normal voltage, V.sub.

Abstract: A circuit breaker for a distribution system includes a non-self-extinction type semiconductor switch, a current limiting element connected in series to the semiconductor switch for suppressing a fault current. The semiconductor switch and the current limiting element constitute a series circuit. A mechanical type high-speed switch is connected in parallel to the series circuit of the semiconductor switch and the current limiting element. Upon occurrence of a fault in the distribution system, an electric current flowing through the distribution system is commutated to the series circuit from the mechanical type high-speed switch.

Abstract: In a relay switching panel, a switching circuit operates to selectively connect and disconnect resistive, capacitive and inductive loads to an AC power source with substantially no arcing. The switching circuit comprises a pair of relays, preferably connected in parallel, with one of such relays having a triac, connected in series therewith. With the relays open, an air gap isolates the power source and the load. In closing the relays in sequence, one relay provides a conductive path from the power source to the triac. After a suitable delay to allow the relay contacts to stabilize in the closed position, the triac is triggered to provide a conductive path from the power source to the load, and a large current surge flows to the load. After the current surge has subsided, the second relay is closed to provide a direct conductive path between the power source and the load. Next the first relay and the triac are removed from the circuit to ensure full conduction through the second relay.

Abstract: Semiconductor switching elements (inverse-parallel connected thyristors) of each main circuit element unit are connected in parallel to a main contact of an electromagnetic contactor. An operation input voltage signal applied to an electromagnetic coil of the electromagnetic contactor is detected by an input-voltage detecting circuit of a control section. When the electromagnetic contactor is closed and opened, a one-shot-pulse generating unit outputs a one-shot pulse based on an output of the input-voltage detecting circuit and a signal indicating an opening/closing state of an auxiliary normally-closed contact of the electromagnetic contactor. The semiconductor switching elements are made on only for a short time by a firing circuit based on the one-shot pulse, to turn on and off a load current.

Abstract: A high power d.c. breaker for connection into a d.c. carrying high-voltage line (L), has two normally closed and electrically series-connected mechanical breaks (BSI, BSII) adapted to be traversed by the line current (I) and to be opened for breaking the current. A capacitor (CB) is connected in parallel with the series connection of the breaks. A semiconductor member (HO) is connected in parallel with one of the breaks (BSI). Upon opening the breaks, a control member (SO) controls the semiconductor member such that a zero crossing of the current through the second break (BSII) is obtained, whereby the line current (I) is commutated over to the capacitor. (FIG.

Abstract: A system and method for protecting relay contacts from erosion utilizes a sensor which senses voltage change in a switch controlling a load relay. In response to operation of the switch, the sensor sends a current to a set of pass transistors which are connected in series to the load power source and the load to turn off the transistors thereby cutting off load current flow to the load. A delay element is connected in series between the sensor and the set of transistors which cuts off the current flow to the set of transistors for a period of time selected to enable the load relay contacts to fully close or fully open before conducting electrical current therethrough.

Abstract: Arrangement for arcless interruption of a-c load current in response to a current interruption command. Separable contact means serially connected with controlled impedance means, and parallel connected diversion means are intermediate the a-c source and the load. The controlled impedance comprises field effect transistors (FETs). Since FETs usually have only a single inherent junction, at least a pair of the FETs are oppositely poled so that load current can be cut off notwithstanding the direction of current flow when interruption is commanded. The pair of FETs may be connected back to back. An alternative embodiment has two branch circuits each comprising a FET and a separable contact means. Upon interruption load current is sequentially transferred from one to the other branch circuit and then to the diversion means.

Abstract: The invention relates to a circuit arrangement for switching current from a contact to a thyristor connected in parallel to the contact. In the inventive circuit arrangement ohmic resistances (7, 8, 9, 10) are connected in parallel to the contact (1), whereby each ohmic resistance (7, 8, 9, 10) can be individually disconnected by means of a delayed-opening contact (3, 4, 5, 6) and the disconnection times are staggered. In this manner, it is possible to accomplish stepwise current switching and thus reliably prevent arcing at the contact (1).

Abstract: A contactor (12) for controlling connection of a DC power supply to an electrical load (14) in includes a series circuit (19) disposed between a nonground DC potential and a load having first (20) and second (22) relays each having a pair of contacts (26), the first relay and the second relay having a conducting state when the pair of contacts are closed and a non-conducting state when the pair of contacts are open which control current flow between the DC power supply and the load with the states being controlled by control signals applied to the relays; a semiconductor switch (24) having a conductive state controlled by a control signal to turn on the semiconductor switch to connect the semiconductor switch in parallel with the contacts of the first relay and a non-conductive state controlled by a control signal to turn off the semiconductor switch to disconnect the terminals of the semiconductor switch; a fault sensor (50) coupled to the load for generating a signal in response to the load drawing current

Abstract: A contact protective circuit for a relay detects a transient in the relay operating coil and turns on a low resistance power MOSFET in shunt relation with the contacts before the contacts close or open whereby arcing or deposition of metal on the contracts is avoided. Timing circuitry is provided for controlling the MOSFET to conduct large direct currents for short periods of time. In one embodiment, a ramp up circuit responds to a voltage level in a control signal to drive the operating coil and power a DC-to -DC converter and a timing circuit. The invention provides for hot side switching as well as cold side switching of a load.

Abstract: The very fast circuit breaker assisted by semiconductor electronics. A piston 21 slides in an insulating housing 20 and along a center shaft 22. The piston 21 has of an exciting winding 25 and a magnetic yoke 26, which by cooperating with an armature 28, join the piston 21 to the center shaft 22, a shoulder of which renders possible the holding of a repulsion disk 34. The repulsion disk carries the moving contacts 35 and 36, which cooperate with the stationary contacts 37 and 38, when the piston is in its high position under the effect of a locking spring 24. Upon the injection of a current into the repulsion coil 45, the repulsion disk 34 is violently repulsed in the downward direction, while jumping the electromagnetic lock established between the magnetic yoke 26 and the armature 28. An admission of compressed air through an orifice 27 permits the descent of the piston 21.

Abstract: A protective circuit for a power pack for exciting or de-exciting a superconducting system has a voltage monitoring circuit at the output of the power pack. A switch in parallel to the output of the power pack is closed by the voltage monitoring circuit as soon as output voltage exceeds a predetermined value in a direction opposite a supply voltage of the power pack. During a malfunction, the switch closes and conducts the current which is being driven by the superconducting coil system. The protective circuit can be utilized in devices such as superconducting magnets of a tomography apparatus.

Abstract: A power integrated-circuit device is protected against load voltage surges. This is done by providing an alternate current-carrying path that is activated only in response to the occurrence of such surges. This alternate path is independent of and separate from the connection that extends between the device and its power supply source. In addition, circuitry is connected to the device to limit the portion of the surge voltage that can appear across critical elements of the device.

Abstract: A device for arcless switching of electrical circuits, wherein power leads of a controlled semiconductor device - transistor 9 are connected parallel to a movable contact (2) and a fixed make contact (3) of a make-and-break contact assembly (1). A control lead of the transistor, which is its base, is connected to a resistor (11) and a fixed break contact (10) of the contact assembly (1), which are components of a control circuit. The movable contact (2) and the resistor (11) are connected to opposite poles of the supply source.

Abstract: A trigger circuit for a spark gap chain with at least two series-connected spark gaps, of which at least one is provided with at least one trigger electrode, includes a resistor chain which is connected in parallel with the spark gap chain and comprises at least two series-connected resistor groups. That of the resistor groups which is connected in parallel with the spark gap provided with a trigger electrode comprises a voltage-dependent resistor, built up of zinc oxide varistors, which is connected in series with a linear resistor. The voltage across the linear resistor is supplied to the trigger electrode of the spark gap for ignition of the spark gap when this voltage amounts to a pre-determined value. The spark gaps are primarily intended to be utilized for overvoltage protection of series capacitors.

Abstract: A switching circuit for supplying electric power to a load from a power source includes a first relay device having a first switch and a semiconductor switching element connected in series with the first switch, power source and load. A second relay device is provided which is defined by a second switch connected parallelly to the semiconductor switching element and an actuating switch for enabling and disabling the semiconductor switching element. The second relay device is so arranged as to effect the make of the actuating switch and second switch in said order and to effect the break of the same in the opposite order. A delay circuit is provided for controlling the first and second relay devices such that when supplying a current to the load, the first and second relay devices are turned on in said order so that the first switch, the actuating switch and the second switch are turned on in said order.

Abstract: The contacts of an electrical switch, such as a magnetic contact reed switch or a magnetic contact reed relay used in a burglar alarm system, are protected from being fused together by transient current surges. This protection is accomplished by providing a normally nonconductive shunting path in parallel with the switch. The shunting path includes a voltage responsive device which is biased to conduction in response to a current surge to thereby complete the shunting path and allow the current surge to bypass the switch.

Abstract: A circuit for protecting the power contacts (18, 20) of automatic bus transfer equipment, including high speed solid state switches (30, 32) connected across the respective contacts. A timing and steering circuit (36) is responsive to the electrical energization of a solenoid (22) for firing the solid state switch (32) connected across the closed contact (18). A timer (48) is responsive to the opening of the contacts (18). At the elapse of a time period, the firing circuit (34) is caused to operate the solid state switch (30) before the closing of the contacts (20). The solid state switch (30) is maintained operated for a predetermined period of time by a timer (90).

Abstract: An electromagnetic device for controlling the supply of current to an electric starter motor includes a pair of fixed contacts on a support for connection to a power supply and a starter motor, respectively. A movable contact which is adapted to engage both fixed contacts is carried by a movable core of an electromagnet so that upon energization of the electromagnet, the movable contact engages both fixed contacts to complete the circuit to the starter motor. A spring is provided for biassing the movable contact away from the fixed contacts upon de-energization of the electromagnet. A flexible braided conductor is permanently connected between the movable contact and one of the fixed contacts to provide an equipotential electrical connection therebetween.

Abstract: A power control switching arrangement for controlling energization of a load in response to an external controller, in which a first semiconductor switch is connected in parallel with the series combination of a first normally open thermally actuated switch and a second normally closed thermally actuated switch, to couple the power signal to the load. A first heater for the first thermal switch is connected in parallel with the load. A second heater for the second thermal switch is connected in series with a second semiconductor switch, across the power supply. The second semiconductor switch, when switched into conduction by the controller, enables energization of the second heater. To energize the load, the controller switches the first semiconductor switch into conduction enabling energization of the load and the first heater. Energization of the first heater closes the first thermally actuated switch, thereby shunting the first semiconductor switch.

Abstract: A switching circuit for supplying electric power to a load from a power source includes a first relay device having a first switch and a semiconductor switching element connected in series with the first switch, power source and load. A second relay device is provided which is defined by a second switch connected parallelly to the semiconductor switching element and an actuating switch for enabling and disabling the semiconductor switching element. The second relay device is so arranged as to effect the make of the actuating switch and second switch in said order and to effect the break of the same in the opposite order. A delay circuit is provided for controlling the first and second relay devices such that when supplying a current to the load, the first and second relay devices are turned on in said order so that the first switch, the actuating switch and the second switch are turned on in said order.

Abstract: The device comprises a solid-state switch and a pair of mechanical contacts electrically connected in series. The solid-state switch is housed in a compartment towards the rear of the moulded case of the device, in thermal contact with an external metal plate. The solid-state switch housing is separated by an insulating partition from the remaining part of the moulded case, which contains the contacts, their operating mechanism, the arc chute and the trip unit. The power terminals and control terminals of the solid-state switch are located on the small side faces of the case on either side of the movement plane of the movable contact, which extends parallel to these small side faces.

Abstract: The circuit breaker displays a commutation device (4) and a semiconductor valve arrangement (6) which is connected in parallel with the commutation device (4), an isolating switching point (5) connected in series with the semiconductor valve arrangement (6) and a control circuit (11). The control circuit detects the polarity of the current to be disconnected and, together with a switching-off command (24), emits a response command to the commutation device (4) when the detected current flows in the direction of conduction of the semiconductor valve arrangement (6). When the current to be disconnected is interrupted in the semiconductor valve arrangement (6) after the commutation device (4) has responded, the control circuit (11) emits a release command to the isolating switching point (5) forming an isolating gap. As a result, the semiconductor valve arrangement (6) is isolated and the switching-off process is terminated.

Abstract: In a circuit having an electro-mechanical relay, the contacts of which are subject to arcing, bridging across the electro-mechanical relay in a manner configured to begin conducting electrical current around the electro-mechanical relay prior to closing the electro-mechanical relay and to continue conducting electrical power around the electro-mechanical relay for a predetermined time after the onset of separation of contacts of the electro-mechanical relay pursuant to discontinuance of current flow through the electro-mechanical relay. An optical coupler is provided to ascertain a current flow through the relay coil effected to close the electro-mechanical relay contacts, and activates a shunt device in bridging electrical current flow around the electro-mechanical relay. The shunt device is provided to be substantially non-load carrying while the electro-mechanical relay is closed. Utility is found in protecting electro-mechanical relay contacts against damage due to arcing.

Abstract: An apparatus for extinguishing the arc which occurs between a pair of electrodes separated in the switchgear when the high voltage loaded switchgear is opened. The earliest arc is detected which occurs between a pair of electrodes. When the earliest arc is detected, a gate signal is transmitted to a pair of thyristor connected anti-parallel between a pair of electrodes. Then among those thyristors, a thyristor located in the forward direction relative to the polarity of power supply becomes conductive. As a result of the thyristor being conductive, the arc occuring between a pair of electrodes is eliminated.

Abstract: An uninterruptible power supply comprising a regulating transformer including output circuitry for connection to a load, first input circuitry for coupling a reserve AC voltage source to the regulating transformer and second input circuitry for coupling a primary AC voltage source to the regulating transformer, the second input circuitry comprising a plurality of winding taps, with each of the taps including a tap switch coupled to the primary AC voltage source.The uninterruptible power supply also includes a voltage control monitor for monitoring the voltage of the primary source and, if the voltage is outside a predetermined maximum allowable range, opening all of said tap switches to isolate the primary source from said transformer, and, if said voltage is within said predetermined maximum allowable range, selectively closing one of said tap switches so that the voltage at the load is held within a predetermined range.

Abstract: In a circuit having a electro-mechanical relay the contacts of which are subject to arcing, a shunt across the electro-mechanical relay configured to begin conducting electrical current across the electro-mechanical relay prior to closing the electro-mechanical relay contacts and to continue conducting electrical power across the electro-mechanical relay for a predetermined time after the onset of separation of electro-mechanical relay contacts pursuant to discontinuance of current flow through the elecro-mechanical relay. An optical coupler is employed to detect the current flow through the relay coil and activate a shunt device to initiate current flow around the electro-mechanical relay. The shunt device is configured to be substantially non-current load carrying while the electro-mechanical relay is closed. Utility is found in protecting relay contacts against damage due to arcing.

Abstract: The circuit breaker-contactor includes a circuit breaker part with mechanical contacts and a contactor part with mechanical contacts connected in series. A solid-state switch is connected in parallel to the contacts of the contactor part. A control unit controls the solid-state switch and the contactor part, in such a way as to close the circuit when the potential difference passes zero by conduction or interrupting the solid-state switch. The mechanical contacts perform only current conduction by shunting the switch in normal operation. The contacts of the circuit breaker part have associated with them an arcing electrode and a shunt circuit disposed to draw the arc, as soon as the contacts open, and to shunt the solid-state switch and contactor part mechanical contacts assembly.

Abstract: A hybrid electrical power controller is provided with a relay having a coil and a pair of mechanical contacts. A solid state switching device is electrically connected in parallel with the mechanical contacts and the parallel combination of that switching device and the contacts is connected between an input and an output terminal. A relay coil energizing circuit is included and means is provided for producing a signal representative of current flowing in the relay coil following deenergization of the relay coil. A solid state switching device control circuit responds to this signal and turns off the switching device when the signals fall below a predetermined magnitude.

Abstract: A solid state current limiting circuit interrupter for the arcless interruption of current through a protected circuit includes a pair of mechanically switched contacts electrically connected in series between the power source and the protected load. A solid state switch becomes electrically connected in parallel across the contacts when the contacts are opened to transfer the current to the solid state switch in a first state of voltage drop lower than arc voltage, and then in a second state of voltage drop higher than power source voltage in which stored energy is dissipated and current is forced to drop to zero to interrupt the circuit.

Abstract: Most contacts that are used in electrical switchgear are prone to erosion due to electrical arcs that are developed at the make and break of a circuit. Arcing is one of the major problems that can cause catastrophic failure of switchgear. In accordance with the invention, a discreet, controlled semiconductor switching assembly is provided within the conventional contact structure to reduce arcing. The semiconductor switching assembly includes a voltage-controlled gate that permits current flow through the contact only when desired. Current is allowed to flow only when the contact gap has been completely closed and is prevented from flowing immediately before the contacts are opened. Thus, there is very little current available to form an arc plasma, and, therefore, erosion of the contact surface is minimal, being mostly the product of mechanical wear.

Abstract: Arcless circuit interruption from metallic contacts is accomplished by the combination of a solid state current interrupter with a control circuit and an impedance circuit. The impedance circuit diverts the contact circuit current through the solid state current interrupter prior to initiating contact separation. The contacts then open without sufficient current transfer to establish an arc.

Abstract: A solid state circuit interrupter utilizes a power transistor connected across a pair of separable contacts to eliminate contact arcing between the contacts upon circuit interruption. Stored charge is provided to the power transistor prior to contact separation by a separate power supply and control transistor which are immediately turned off after contact separation to turn off the power transistor upon depletion of the stored charge.

Abstract: A power control and diagnostic arrangement illustratively embodied in an electric range having multiple surface heating units which are selectively coupled to an AC power supply by commutated relay switching circuitry. The commutated relay switching circuitry includes two switching networks. Each network includes a diode commutated master relay serially connected to a pair of pilot relays. Each pilot relay is serially connected to one of the surface units. Timing and control circuitry periodically interrupts operation of the power circuit in a normal mode to operate in a diagnostic mode. In the diagnostic mode the relays are switched in a predetermined sequence to test for a short circuit failure of the master relays or commutated diodes, an open circuit failure of the diodes, an open circuit failure of the master relays, a short circuit failure of the pilot relays and an open circuit failure of any individual pilot relay.

Abstract: A gate turn-off thyristor is connected across a pair of separable contacts for diverting the interrupted current first to the thyristor and then to a metal oxide varistor connected across the thyristor. A saturable core current transformer in combination with the capacitance provided by the metal oxide varistor turns on the thyristor when the contacts separate and turns off the thyristor after the contacts have further separated when the core becomes saturated.

Abstract: A switch comprises a mechanical switch element having contacts and a semiconductor switching element, the mechanical switching element and semiconductor element being connected in series or in parallel with each other with respect to the output terminal and integrally formed in a housing. The semiconductor element and the connections thereto are embedded in an insulating material within the housing.