Abstract: Protection of the thin gate oxide of MOS field effect transistors from irreversible puncture due to undesired high voltages and currents generated by electrostatic discharge through handling or otherwise, is provided by a circuit structure at each input pad of an integrated circuit chip. One such feature includes the use of a barrier layer of polysilicon material to make an electrical contact between source and drain diffusions of a protective transistor and their respective aluminum conductors, in order to increase the amount of current that can be handled at such contacts without the aluminum conductor fusing though a diffusion into the substrate. Another such feature is to provide an initial, and perhaps only, protective transistor that has a very narrow channel between source and drain diffusions to allow a reversible breakdown to reduce the voltage across it to within, or nearly within, the maximum voltage that the protected thin gate oxide transistor can handle without being damaged.

Abstract: An underoil surge arrester (10) having metal oxide varistor disks (12) held in place by flexible spring clips (18).

Abstract: An integrated circuit has an input protection circuit coupled between an input pad and an input circuit. The input pad receives a signal provided externally from the integrated circuit. The input circuit is responsive to the signal provided externally from the integrated circuit. The input protection circuit provides protection against electrostatic discharge (ESD). The input protection circuit includes two polysilicon resistors in parallel in which one has a greater width than the other. The greater width resistor will be the first to open under ESD stress leaving the other resistor to still provide a signal path between the input pad and the input circuit.

Abstract: A transient voltage surge suppressor including first and second clamping stages with a surge reactor between the stages. The first stage comprises a metal oxide varistor and the second stage comprises a silicon surge suppressor diode. The surge reactor comprises first and second coils wound with the same polarity on a single ferromagnetic core.

Abstract: A method and apparatus for protecting electrical circuits by suppressing voltage and/or current transients while simultaneously filtering unwanted noise, such as electromagnetic interference (EMI), at specially selected frequencies, by controlling the spatial array of devices in an electronic package to tailor the impedance versus frequency characteristics of the overall package.

Abstract: A solenoid operated directional control valve includes a visual position indicator assembled of rectifying bridge circuit whose DC output terminals are bridged by a series connection of a light emitting diode with a PTC resistor. In this manner, the indicator is universally applicable both for DC and AC power sources and for a wide range of supply voltages.

Abstract: An electric motor armature current control circuit includes an electric motor with an armature in series with a protective device comprising a pair of polymer PTC elements connected in electrical series with the motor armature windings and in electrical parallel and thermal contact with each other. The first polymer PTC element, a temperature compensating element, has a very low cold resistance and a trip temperature higher than the maximum expected ambient temperature to which it is to be exposed in motor operation and generates heat in motor operation to trip to a much higher resistance and become self-regulating at that trip temperature. The second polymer PTC element is maintained at least at the trip temperature of the first through thermal contact and has a lower resistance at that temperature than the cold resistance of the first. Its trip temperature is higher so as to be reached only with excessive armature current.

Abstract: A static switch is provided for controlling the closing and opening of an AC electric circuit including an inductive load. This switch includes an inhibitable thyristor having an RCD network for protection against the voltage gradients on turn-off. The anode-cathode path of the inhibitable thyristor and its protection network are connected to the AC energy source through a full wave rectifier device, whereas a voltage clipping member is disposed at the terminals of the rectifying device.

Abstract: An automatic safety switch apparatus is provided for interrupting power to an electrical appliance such as a cooking stove after a predetermined period of operation. The apparatus includes a current detector for sensing a threshold current level between a power source and the appliance, a timer responsive to the detector, and a relay driven by the timer for opening a circuit between the source and the appliance. The timer, which can be programmed to provide a maximum interval of time during which the appliance can be safely operated unattended, is automatically reset when the appliance is turned off.

Abstract: An ECL circuit includes a plurality of input terminals, a current source, a reference transistor having an emitter connected to the current source, a base receiving a reference voltage and a collector connected to a first resistor, a plurality of input transistors each having an emitter connected to the current source, a collector connected to a second resistor and a base connected to one of the input terminals, a plurality of pull-down resistors each connected between the base and the emitter of one of the input transistors, an emitter follower transistor having a base connected to the collector of the reference transistor or a common connection point of collectors of the input transistors and an emitter connected to an output terminal and a third resistor.

Abstract: A device for protecting a DC series electric motor from the voltage surge which occurs when the motor fields collapse. Electrical resistances are connected in parallel with the series field coils and the commutating field coils of the motor. The resistances safely absorb any voltage surge resulting from field collapse and also protect the motor from externally generated voltage spikes.

Abstract: Each phase circuit comprises a static switch of the IGT or GTO type, between the anode and the cathode of which there is arranged in parallel a series mounting of a CTP resistance and of a normally open switch which is closed when a current detector detects a short abnormal intensity lower than six times the rated current; said static switch is locked either immediately when the rate is higher than six, or with a short delay on the contrary. Said device is particularly convenient to be used in industrial installations where it is desired to replace the associations of contactors, thermal relay and circuit breaker by static apparatuses.

Abstract: An oxide fuse, and method of forming same, formed by a thin layer of oxide dielectric between a lower electrode substrate and an upper electrode. A fuse-programming bias of approximately 15V causes Fowler-Nordheim tunneling at low temperature to damage the dielectric layer, and shorts the upper and lower electrodes together. The oxide layer is advantageously formed simultaneously with the gate oxide layer in an EEPROM.

Abstract: An electronic fuse is intended to be triggered should the current from a load (LA) exceed a predetermined value. The load current is restricted first by a switch in series with the load, the switch being kept in a closed or open state by pulses from a pulse length modulator (PB). The pulse length of the modulator is controlled by a sensing circuit (AK) such that when the load current exceeds the predetermined value, the circuit sends a control signal varying as the load current, so that the closing time of the switch (OM) decreases with increasing load current. After a practically contant time the switch is thereafter set to a permanently open state.

Abstract: The severity of the problems of transmitting high speed data over a regular twisted wire pair are legendary. These problems arise from a variety of conditions, including the capacitance of the wire (which increases with length) and the propensity of unshielded wire to pickup high induced voltages. An arrangement is disclosed that is suitable for short, as well as long, wire distances and which also effectively eliminates the interference problem caused by induced voltages, including those causes by electrostatic discharge. This arrangement passes two twisted wire pairs through a series of ferrite cores. The twisted wire pairs coming out of the ferrite cores are terminated such that one of the pairs is connected to ground while the signal carrying twisted pair is connected to a small signal balun coil, pulse shaping circuit and low pass filter.

Abstract: The medical current limiting circuit is for use with medical electrodes and associated diagnostic and therapeutic apparatus. The device protects the apparatus and patient from current flow. The device has circuitry comprising a pair of external connectors, a pair of n-type field effect transistors connected in cascade, a resistor, a p-type field effect transistor, a capacitor to latch the p-FET in a non-conductive state upon its initial activation and a diode to prevent capacitor discharge to the current source.

Abstract: A high-voltage system surge eliminator for the protection of electric transmission and distribution stations against line and switching transients, atmospheric discharges and other adverse effects including such as those caused by lightning. The eliminator is suitable for the protection of substations and of individual equipment units, selectively, and is applicable to both direct current and alternating current single and multi-phase systems, selectively. Two basic and typical eliminator varieties are shown and described.

Abstract: A rotary telephone line surge protector and system in which surge protector comprises a first and second housing, the second housing containing a grounding plug and non-conductive plug prongs to connect the second housing to a standard AC electrical wall outlet and which first housing is adapted for rotary motion about the central axis of the second housing, and the second housing having a conductive grounding plate therein, and the first housing containing one or more telephone input jack receiving inlets, a surge protector circuitry means including resistors to receive and dissipate any overload voltage from the connecting telephone line, a rotary arm containing a plurality of arms for rotary movement with the first housing and the arms in a tension-biased contact with the grounding plate, the first housing in the rotary arm adapted to move about a central axis relative to the secured second housing, and telephone jack receiving inputs to receive therein any standard telephone jack to provide an incoming te

Abstract: A gas insulated apparatus for high voltage, 3-phase applications in which an insulating, self-arc-extinguishing gas separates the high voltage lines from grounded vessels. According to the invention, the transverse impedance of the vessels is chosen so that a normal voltage impressed on the lines will produce a current through the resistive vessel that will be extinguished by the gas.

Abstract: A protected output switch for an implantable medical device, such as a pacemaker, is disclosed. Through this output switch, a stimulation pulse is delivered from an internal storage element to an output terminal. The output switch includes a first N-channel MOSFET switch having its source terminal connected to the internal storage element and its drain terminal connected to the output terminal. The gate terminal of the N-channel MOSFET switches is connected to approriate logic switching signals. Included as part of the output switch is a second N-channel MOSFET switch having its source terminal connected to the P-well terminal of the first N-channel MOSFET switch, its drain terminal connected to the internal storage element, and its gate terminal connected to the output terminal. This second switch serves to block any potentials, whether internal or external, from being applied to the base of a parasitic NPN bipolar transistor that exists within the output switch.

Abstract: A high-speed current limiting circuit breaker comprises a self-recovery type current limiting element for limiting a fault current, a parallel resistance connected in parallel with the self-recovery type current limiting element and a circuit breaker connected in series with the self-recovery type current limiting element, a fault voltage detector for detecting the voltage generated on the parallel resistance and thereby driving an electromagnetic repulsion coil for breaking the circuit breaker.

Abstract: This disclosure relates to a voltage surge arrestor for use with an electric device having a component to be protected from a voltage surge. The arrestor comprises at least first and second electrodes, and a spacer connected to the electrodes and mounting the first and second electrodes in spaced relation. The electrodes have portions which are spaced relatively close to each other and form a gap therebetween, and a gravity movable member is in the space between the electrodes and movable by gravity into and out of the gap, thereby changing the voltage breakdown level in the gap. The arrestor further includes a voltage and current limiting block connected to one of the electrodes. The movable member may be electrically conductive or a dielectric member, and it may be liquid or solid.

Abstract: A filament bypass circuit for use with a string of lamps in series capable of continuing current flow when a lamp in the string fails. Each lamp is provided with a shunt circuit consisting of a series circuit of a diode and a silicon bilateral voltage triggered switch. The switch becomes conductive upon the application of a substantial increase in voltage from the A.C. source and remains conductive until there is an interruption of current flow or current flow drops below its required holding value. The diode insures that during continued operation after a failure there will not be an excessive voltage applied to the remaining lamps, and also serves as an indicator of a failed lamp.

Abstract: Load current is diverted from a circuit breaker, when it is opened, through a commutation circuit. The latter has a capacitor, inductance and solid state switch serially connected with the output of a bridge rectifier. The input of the bridge is connected across the breaker. The switch is turned on to discharge the precharged capacitor to form a current pulse, presenting an extremely low resistance across the bridge input and causing load current diversion.

Abstract: There is disclosed a surge current-limiting circuit including a current-limiting means connected in series with a load; a controlled rectifier connected in parallel with the current-limiting means; a photocoupler; and a delay circuit having a time constant, connected through the photocoupler with the gate of the controlled rectifier.

Abstract: A device for preventing contact defacing and arc prevention which comprises a triac bearing a momentary opening or shutting of a current, fixed terminals (A) and (B) bearing the continuous current, further in the terminals (A) and (B) no arc occurring at opening and closing, therefore a silver contact becomes unnecessary.

Abstract: An AC current limiter for a power transport line including an overload circuit-breaker member (6), the limiter comprising a transformer having a primary winding (6A) connected in series between the power supply circuit (R) and the load circuit (U) and one or more secondary windings (9) of superconductor material contained in a cryogenic enclosure (11) and short-circuited on themselves, the leakage reactance of the transformer as seen from the primary winding being low, and the resistance of the, or each, secondary winding when in the non-superconducting state and as seen from the primary being much greater than the nominal impedance of the transformer.

Abstract: A pre-insertion inductor arrangement is provided for a circuit interrupting device or high voltage switch to reduce audible and electrical noise and to limit transient inrush current and/or voltages upon closing of the circuit by the circuit interrupting device or high voltage switch. The arrangement provides the insertion of the inductor for a plurality of cycles of the source frequency and thus does not require precise timing. The pre-insertion inductor does not require the use of a stack of resistor blocks or cakes of the prior art. Further, since the pre-insertion inductor has relatively low losses, the energy dissipation requirements of the pre-insertion inductor are significantly less than for pre-insertion resistors. Additionally, since the pre-insertion inductor is not continuously in the circuit, there is no requirement to carry continuous load or fault current or to accomodate losses on a continuous basis.

Abstract: Power to a load is controlled by actuation of an inductive circuit from a first condition of low inductance to a second condition of higher inductance in response to a preselected overcurrent condition. In a first preferred embodiment, the inductive circuit comprises a pair of coils electrically connectible so that magnetic fields produced by current flow in the coils oppose each other in the first condition, reducing the magnetic flux and thus the effective inductance of the circuit. The magnetic fields are either neutral to each other or reinforce each other in the second condition, giving rise to a higher inductance. Alternatively, the inductive circuit may include one or more fixed value inductors interposed between a power supply and a load in response to an overcurrent condition.

Abstract: An inductive device composed of a bead (10) of magnetic material, such as ferrite, has an aperture through which an electrical conductor (13) is adapted to pass and a reset winding (14) wound thereon and connected to a source of constant current. The constant reset current resets the bead of magnetic material so that the maximum volt-second absorbtion capability of the bead is available for preventing destructively high current spikes from flowing through the electrical conductor. The inductive device is advantageously used in the d.c. supply of the power transistors (101 and 102) of an inverter (100) to protect the transistors from current surges due to the simultaneous conduction of the transistors.

Abstract: A power contact with low off current for switching a-c loads in response to a logic signal includes a rectifier bridge circuit in a series with the load and the a-c power source, a MOSFET connected across the d-c terminals of the bridge, and a series RC filter circuit in parallel with the MOSFET. A metal oxide varistor connected across the d-c side of the bridge protects the MOSFET from transients in the a-c circuit. While this power contact is capable of switching sizable a-c currents, the leakage current with the MOSFET off is less than 1/10 of a milliamp so that it can also be used to switch loads which draw very low level currents. The MOSFET is electrically isolated from the logic signal by an opto-isolator which has a unique switchable output which permits the power contact to be readily adapted for use with normally energized or normally deenergized loads.

Abstract: A spark suppression circuit for a battery charger includes a large filter capacitor connected in series with a semiconductor switch across the terminals of the battery charger. The battery charger does not have any output voltage even though the input is energized because the circuit includes a device to delay supplying of voltage until after the charger output terminals are connected to a battery to be charged. The semiconductor switch is non-conductive until the battery charger output terminals are actually connected to the battery to be charged. At this time, a bias circuit connected across the charger output terminals supplies a bias to turn on the semiconductor switch so that only at that time is the filter capacitor connected across the charger output terminals, and hence this suppresses the possibility of a spark upon connection of the charger output terminals to the battery to be charged.

Abstract: An acceleration power supply includes a series-connected semiconductor switches with voltage dividing elements and another semiconductor switch coupled in series to the series-connected semiconductor switches for cutting off a power supply line connected to a load of the apparatus. The series-connected semiconductor switches and cutting-off semiconductor switch have a function of a series regulator.

Abstract: Apparatus for testing the dielectric strength of insulating and/or cooling media, particularly insulating oils for electrical apparatus and equipment such as transformers, converters, switches or the like wherein a vessel is provided within which the material to be tested may be contained with electrodes providing a spark gap arranged therein being connected to the high voltage side of a testing generator having a transformer and a voltage control device, the internal resistance of the testing generator being made voltage-dependent and increasing with increasing voltage.

Abstract: An overcurrent protection circuit including a first transistor, a second transistor, and an integrator. The first transistor operates to control a current flow from a power source to a load. The second transistor is turned on when an overcurrent flows through the first transistor. The overcurrent is detected by watching the collector-emitter voltage of the first transistor. Thus, the second transistor operates to bypass the base current to be supplied to the first transistor with a certain delay time defined by a delay part, which enables an instantaneous overcurrent to be ignored.

Abstract: An intrinsically safe safety barrier includes an outgoing line, a return line, two switching transistors connected in the outgoing line, at least two control transistors having base-emitter circuits for controlling the switching transistors in order to regulate current when current increases in the outgoing line, and a single sensing resistor connected in the outgoing line in the base-emitter circuits of each of the control transistors.

Abstract: An arc suppression circuit for a switch carrying a load current includes a MOSFET having a drain connected to a first contact of the switch and a source connected to a second contact of the switch. A biasing capacitor is coupled at one end to the drain and at another end through a damping resistor to the gate, such that when the switch contacts are opened, the interrupted load current passes through the biasing capacitor to charge an inherent gate-to-source MOSFET capacitance for turning on the MOSFET and shunting the load current around the switch. A biasing resistor, connected between the gate and the source of the MOSFET, subsequently discharges the gate-to-source capacitance, turning off the MOSFET and terminating the shunted load current after the contacts of the switch have separated by a distance sufficient to preclude arcing.

Abstract: A series capacitor bank for connection into an electric power supply network is provided with overvoltage protective equipment having two branches connected in parallel with the capacitor bank. The first branch comprises a first zinc oxide varistor in series with a linear resistor and the second branch comprises a varistor with a higher "knee" voltage than the first zinc oxide varistor. The resistance of the linear resistor is preferably of the same order of magnitude as the absolute value of the impedance of the capacitor bank at the operating frequency of the power supply network. The "knee" voltage of the second varistor is at least 1.15 times (and preferably not more than 2.0 times) the "knee" voltage of the first varistor.

Abstract: In order to prevent an excessively fast rise of the programming voltage for an (E)EPROM, a stage is inserted which on the one hand prevents voltage losses and which on the other hand realizes the required large time constant of the voltage rise in spite of the use of small capacitances.

Abstract: Fault-protection is added to static AC-to-AC converter to protect the GTO devices bilaterally by adding at least two line bridges of diodes having an inductor thereacross. Fault-protection is extended to a UFC system by incorporating such inductor in the diode bridges of the GTO devices forming the bilateral switches of the UFC system. The dissipating energy is minimized by combining such fault-protection bridges. The inductors may be coupled controlled demagnetization of the inductors is provided.

Abstract: Circuit protection devices comprise a PTC conductive polymer element within a hollow enclosure which is sealed except for at least one vent. The vent is sealed by means of a cover member, preferably of adhesive tape. The exterior surface of the enclosure adjacent the vent and under the cover member is provided with indentations which change the internal pressure required to blow the cover member off the vent, and/or enable the cover member to open during a hot washing step and subsequently to reseal without admitting wash liquid, and/or control the direction in which gases flow after passing through the vent.

Abstract: An MOS current limit circuit which provides current limiting protection is provided. A driver transistor of a conventional output stage is coupled to a current limiting transistor which is one transistor of a current mirror. The current limiting transistor of the current mirror has the V.sub.GS thereof accurately biased to insure a precise current limit value. When the current limiting transistor is not performing a current limiting function, the current limiting transistor is made conductive and further provides high voltage protection to the driver transistor when the driver transistor is nonconductive.

Abstract: A current limiting apparatus is provided with a pair of generally parallel conductive rails each including an initial high conductivity portion and a more resistive portion. A sliding armature conductor is positioned between the rails and makes sliding electrical contact with the rails such that a high fault current flowing through the rails and through the armature conductor produces forces which propel the armature conductor along the rails thereby increasing the resistance through which the current flows. Final interruption of the current is accomplished by a separate circuit breaker which is connected in series with the current limiting apparatus.

Abstract: A current limiting apparatus includes at least two pairs of generally parallel conductive rails each having an initial high conductivity portion and a more resistive portion. A sliding armature conductor is positioned between each pair of rails and makes sliding electrical contact with the rails such that a high fault current flowing through the rails and the associated armature conductor produces forces which propel the armature conductor along the rails thereby increasing the resistance through which current flows. The pairs of rails are geometrically associated such that current flowing in each pair of rails augments the accelerating force on the armature conductor located between the other pair of rails. Additional accelerating force augmenting may be provided by a multiple turn coil located near the high conductivity portions of the rails.

Abstract: Method and apparatus are provided for an emission controlled current limiting device. The apparatus may control the current thermionically, by cold cathode emission, by photo-emission, or with plasma devices; the common feature being that the current is limited by controlling a series emission process. The apparatus has applications in both power line transmission and distribution networks to protect existing utility equipment and reduce the cost of new equipment.

Abstract: A power line transient surge suppressor circuit features a nonlinear surge-bypassing network connected to bypass line surges around electrical loads connected to circuit output terminals. A fuse is inserted in series with the network, and blows in the event of short-circuit failure of a regulator device in the network. A thermal cut-out preferably of the irreversibly actuated type is inserted in series with the suppressor circuit input. A current-limiting heater resistor connected in parallel with the fuse supplies heat to trip the cut-out after the fuse blows, thereby permanently terminating power output to the loads. A similar suppression network is provided for the earth lead in three-wire systems.

Abstract: A method and apparatus for preventing latch-up caused by spurious signals reaching the input and output ports of an IC. The apparatus consists of a current regulating diode that limits the current entering the IC to a level below the latch-up holding level preventing the IC from being latched up. The method and apparatus further allows the recovery of an IC that has been latched-up through external transient ionizing radiation by limiting the current through the IC below the latch-up holding current level.

Abstract: A current limiting device has a reactor including an intermediate terminal, a capacitor connected in series between one external terminal of said reactor and said intermediate terminal of said reactor and a closing means as well as a resistor, wherein the other external terminal of said reactor and the connection terminal of said capacitor and said closing means are respectively connected to different A-C systems.

Abstract: In a power supply system having a grounded neutral and supplying service equipment through a distribution transformer, a ground voltage suppression device comprises a saturating inductor or like non-linear impedance device connected between the secondary neutral conductor and a normal ground conductor so as to define therewith a neutral-to-ground current path which presents a high impedance to current flow for applied voltages up to a predetermined level.

Abstract: An improved general service incandescent lamp having an improved capacitive ballast circuit for operating a low voltage filament of the lamp is disclosed. Various embodiments of an improved capacitive ballast circuit that substantially eliminates unwanted stored energy and unwanted resistive dissipation are disclosed.