Abstract: A network interface apparatus for connecting incoming and subscriber coaxial transmission lines and having a coaxial transmission line surge arrestor connected in series between the coaxial transmission lines, the surge arrestor comprising a gas discharge tube having a hollow conductive housing and a center conductor having a longitudinal axis parallel to the direction of signal transmission, the interior surface of the hollow housing and the exterior surface of the center conductor being symmetric with respect to the longitudinal axis, ratio of the inner diameter of the conductive housing to the outer diameter of the center conductor being varied within the gas discharge tube for matching the impedance of the surge arrestor to that of the transmission line.

Abstract: A circuit for providing electrostatic discharge (ESD) protection is disclosed. The circuit comprises a pair of CMOS field effect pull up and pull down transistors with reduced resistance source and drain, having a well resistor formed external to them between supply and ground busses respectively. During an ESD event, the well resistors serve to both limit the current flow through the transistors, and reduce the voltage drop across them.

Abstract: A ground fault circuit interrupt system with auxiliary surge suppression ability is provided which includes line-side system, phase, neutral and ground terminals electrically connectable to phase, neutral and ground terminals of an AC source and load-side system, phase, neutral and ground terminals electrically connectable, respectively, to phase, neutral and ground terminals of an electrical load. The system includes a ground fault circuit interrupter including line- and load-side phase and neutral ports for electrical connection to the line-side system, phase and neutral terminals for controlling a state of conduction of AC between the source and electrical load in accordance with a detection of an interrupt condition.

Abstract: A power distribution circuit is provided that isolates both power source and load faults. In one embodiment, the power distribution circuit includes two power MOSFETs connected with the channels of the power MOSFETs in series and having their gates electrically connected together. The body diode of one power MOSFET is aligned with the opposite polarity with respect to polarity of the body diode of the second power MOSFET. The power MOSFETs are adapted to be coupled between a first power source and a load. The power distribution circuit also includes a first sensor that detects when the power MOSFETs conduct too much current and switches the power MOSFETs off by discharging the gate voltage of both power MOSFETs during such overcurrent conditions. Accordingly, when both power MOSFETs are switched off, the opposing polarity of the body diodes in the power MOSFETs ensures that one of the body diodes will be reversed biased in case of a short circuit failure in either the load or the power source.

Abstract: A circuit for protecting a bonding pad of a semiconductor device from ESD voltages is located under the pad to permit the space otherwise used for a protection circuit to be used for normal operating components. The protection circuit has a compact layout that provides maximum ability to handle an ESD current within this limited space. The semiconductor structure for the circuit has separate parts for two SCR circuits, one for each polarity of ESD current. Each SCR circuit comprises two symmetrical SCR structures.

Abstract: An improvement in conditions that protective functions of an insulated gate semiconductor device with a protection circuit incorporated therein are performed, an improvement in the cutoff of heating, the prevention of malfunctions and an improvement in ease of usage can be achieved.The insulated gate semiconductor device of the present invention comprises a power insulated gate semiconductor element (M9), at least one MOSFET (M1 through M7) for a protection circuit, for controlling the power insulated gate semiconductor element, a constant-voltage circuit using forward voltages developed across diodes (D2a through D2f) for the constant-voltage circuit, and voltage restricting diodes (D1 and D0a through D0d) for controlling the upper limit of a power supply voltage of the constant-voltage circuit. Power to be supplied to the voltage restricting diodes is supplied from an external gate terminal of the power insulated gate semiconductor element.

Abstract: In order to achieve improved release characteristics in the case of a protective device for power supply lines, a protection release method is proposed in which at least one signal (i, u) is supplied to a filter device (3, 16), and a release decision is made as a function of its output signal (SA, Z). If the conditions are insufficient for release, a change is made to the filter characteristics. The filter device (3, 16) in this case preferably comprises adaptive filters or combinations of filters. In a further refinement, a fuzzy region, which is used as the release criterion, is formed as a function of a change in the output signal.

Abstract: An electrical extension cord with built-in safety protection includes an electrical cable formed with insulated phase, neutral and ground conductors surrounded by a braided sensing shield. An electrical receptacle is electrically connected to the cable at first ends of each of the phase, neutral and ground conductors, and the shield is electrically connected to the ground conductor. A ground fault circuit interrupter (GFCI) is electrically connected to the cable at second ends of the phase, neutral and ground conductors, within which the ground conductor is electrically coupled to the shield through a predetermined impedance such that leakage current is collected by the shield and detected by the GFCI.

Abstract: The disclosure relates to the protection circuits interposed between a DC supply and a load circuit to protect the load circuit against short-circuits or reversals in polarity of the supply. The protection is obtained by means of a MOS power transistor connected between the supply and the load circuit. This transistor is turned on if it receives a voltage Vg from a bias circuit through a control circuit. The bias circuit delivers the voltage Vg only if the voltage given to it by the supply is sufficient while the control circuit turns the power transistor off if the output of the supply gets short-circuited or gives a voltage with reversed polarity.

Abstract: A circuit and method for interrupting an AC load current includes a first MOS Controlled Thyristor (MCT) for selectively interrupting the load current. The current through the first MCT is reduced when the load current is to be interrupted by providing a pulse resonant commutation (PRC) current through the first MCT which flows in a direction opposed to the AC load current direction and which has a magnitude reducing the current through the first MCT to an MCT "off" condition (e.g., when a voltage across the MCT is reversed, when there is near zero current through the MCT, or when a current is within the MCT's SOA.) The first MCT turns itself off when MCT gate voltage is an "on" voltage and when reverse voltage is across the MCT. An MCT "off" voltage may then be provided by sensing MCT current and providing an "off" voltage to the MCT gate when the sensed current indicates that the MCT is an "off" condition.

Abstract: A broadband communications network having an uninterruptible power supply. The power supply has one input connected to AC line voltage and another input connected to a gas powered electrical generator. The power supply contains an uninterruptible power supply module having a controlled ferroresonant transformer and a battery. The power supply also contains a bypass module having a controlled ferroresonant transformer. Switches are provided to allow either of the inputs to be connected to either the UPS module or the bypass module for the generation of power signals for supplying power to the broadband communications network.

Abstract: Power cable includes, along with standard conductor wires encased in insulation, a heat responsive cable alongside the conductor wires. The heat responsive cable includes helically wound wires each coated with heat sensitive dielectric, The two wound wires at one end are oppositely connected to an alarm and to a main power switch, forming a normally open safety circuit. The dielectric on the heat responsive cable is subject to vaporization in response to a fault in the power cable, whereby the wound wires make electrical contact to close the safety circuit, activate the alarm, and open the main power switch.

Abstract: The present invention provides an arrangement for automatic selective circuit interruption in response to detection of a fault in a multi-phase distribution system feeding a plurality of network branches. The arrangement includes a plurality of line monitoring devices which are programmed to alarm a control station in response to detection of a fault in the system. In response to being alarmed by one or more line monitoring devices, the control station activates a specialized signal generator which produces a specialized signal along one of the lines of the multi-phase system. Each line monitoring device is co-located with and communicatively coupled to a circuit interrupter which, when actuated, prevents the flow of current in lines of the system positioned downstream from the actuated circuit interrupter. Each line monitoring device automatically actuates the coupled circuit interrupter within a prescribed period of time following detection of the specialized signal.

Abstract: A household electrical service (10) is protected against overheating by running a sensor line or wire (36 or 38), coextensively together with hot, neutral and ground lines or wires (12, 13, 14 or 31, 32, 33), from a power company hookup (50) to a main breaker switch (18), and from respective branch circuit breakers (19) throughout the branch circuits (21, 22). The sensor line or wire (36 or 38) may be a length of heat fusible or otherwise temperature variant material which has a load end connected to ground and a source end connected to a control circuit (51) which trips the breaker (18 or 19) when an overtemperature condition melts the wire. Protection is extended through to individual devices (43) by continuing the sensor wire through the device cord (42). For this purpose, a plug ground prong (46) and receptacle ground prong connection (45) provide isolated ground and sensor wire connections.

Abstract: Digital processing of current signals allows close matching of arbitrary time delay curves for a circuit breaker. An analog signal proportional to the current is sampled and digitized. Digital samples, with or without further processing, are used to select increment values from a look-up table for accumulation in a counter. The counter is decremented periodically to simulate cooling of the circuit being protected. The values in the look-up table are determined according to the desired time delay curve. Processing of the digital samples may include squaring samples, accumulating the squared values to form a subtotal which is compared with an instantaneous trip threshold, accumulating the subtotals for a time period equal to half a cycle of AC line voltage, taking the square root of the accumulated subtotals, and using that square root as the address for looking up the increment value.

Abstract: The disclosed invention is designed to prevent the oscillation which often occurs in an over-current protection apparatus for an insulated gate controlled transistor. The apparatus improves the response in current detection, to prevent oscillation, and improves protection speed against over-current.

Abstract: A portable apparatus to test an automobile wiring harness for the location of a short in one of the wires. A transmitter is used to apply a low frequency, low duty cycle, pulsed signal to the wire under test. A receiver, with an inductive sensor, detects magnetic fields generated by the pulsed signal current flow between the transmitter and the short. The receiver generates a humanly discernable signal in response to the detected magnetic field. The operator finds the short by following the detected magnetic field of the signal pulse through the wire under test. By noting the location of a dramatic discontinuity in magnetic field strength, the operator can gauge the location of the short in the wire. The low voltage amplitude, low duty cycle, pulse signal allows the transmitter to be operated with a small battery. The low power signals also provide safety to circuits connected to the wire. The low frequency and power of the pulsed signal minimizes coupling between wires.

Abstract: Transient voltage surge suppression (TVSS) located conveniently between the conventional plug-in watt-hour meter and its socket at a customer's location. Over-voltage means, such as one or preferably more metal oxide varistors, are supported there, as in a cylindrical housing called a meter adapter. The varistors connect electrically between power leads and an external ground lead to clip voltage transients and to shunt resulting surge currents harmlessly to ground. Varistors may be inserted into suitable holders therein or may be prepackaged and be retained therein within such prepackaging. One terminal and preferably a face of each varistor is contiguous with an extensive laminar conductor within the adapter in the pathway to ground so as to accommodate extremely surge currents and to aid in dissipating resulting accumulation of thermal energy.

Abstract: An electronic device protecting apparatus and associated methods of manufacturing provide protection for electronic devices which receive power for their operation at least in part from a storage battery. In a preferred embodiment, an electronic device protecting apparatus has a battery voltage sensor, an engine start sensor, and an electronic device decoupler. The electronic devices are decoupled from the battery when the battery voltage drops below a predetermined level, and when the engine is being started.

Abstract: An active terminator comprises a thermal shutdown circuit. When this circuit detects a predetermined high temperature, this information is supplied to a driver, and the active terminator stops operating. The signal from the thermal shutdown circuit is also supplied to an RS latch circuit that stores information to the effect that the thermal shutdown circuit has detected high temperature, and that the active terminator has stopped operation. A computer examines the contents of this RS latch circuit so that it can be determined that the terminator has stopped operating, and communication errors can therefore be prevented by, for example, reducing the data transfer rate accordingly.