Abstract: A faulted circuit indicator includes an inrush restraint circuit that suppresses a trip signal when an inrush current rises from below a minimum value to a trip value within a predetermined time and then drops again to another value such as the trip value. According to various aspects the restraint ends after a fixed time or after a variable time. According to another aspect a second trip circuit overrides the inrush restraint circuit when the current rises a given amount beyond the first trip value.

Abstract: A surge suppressor suitable for protecting railroad switching systems from lightning directly striking a rail of a railroad track includes a pair of spark gap surge suppressors each coupled between a ground conductor and a corresponding rail. A spark gap equalizer is connected between the first and second conductors coupled to the rails, respectively. A first inductor is connected between the first conductor and a first output terminal, which is coupled to an input of the railroad switching system. A second inductor is connected between the second conductor and a second output, which is connected to another input of the railroad switching system. A first surge suppressor diode is connected between the first and second output conductors, and a second surge suppressor diode is connected in the opposite direction between the first and second output conductors.

Abstract: A method of locating a phase-to-ground fault in a radial distribution system with a tapped load. The method includes determining the positive-sequence impedance from the residual current, the residual current compensation factor and the phase-to-ground voltage of the faulted line. The positive-sequence impedance is then used to determine the distance to the fault.

Abstract: A ground fault circuit interrupter is described which provides protection in the event of loss of neutral or ground, excess potential between neutral and ground and reversed input connections. Separate, independent tripping circuits are used for these latter faults and for ground faults, thus eliminating problems due to interfering signals and reducing reliance on any one component or group of components. An opto-emitter and opto-detector arrangement is used for detecting and causing tripping of a circuit breaker in the event of faults other than ground faults.

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: An apparatus for differential-protection of a bus bar having a plurality of terminals which includes a plurality of trunk lines, in which an impedance of a differential circuit connected in parallel to a current transformer provided in each of the terminals is changed depending on either a terminal voltage of this differential circuit, or another terminal voltage derived from a part of the impedances. Then, either a high impedance differential relay, or a low impedance differential relay is selectively available so as to confirmly detect a fault in the bus bar.

Abstract: A bushing cap is provided for mounting to a transformer bushing or to a lightening arrestor. The bushing cap when mounted to the bushing acts as an umbrella for the bushing to protect the same from airborne contaminates such as salt spray which can form a conductive surface on the bushing, while providing adequate bottom and side clearance from the bushing to ensure that a conductive surface between the cap and the bushing is avoided.

Abstract: The disclosed faulted current indicator senses current in a line having a breaker or fuse, and avoids tripping in response to current inrush signals by producing a trip signal in response to an overcurrent occurring for an overcurrent duration which is inversely related to the magnitude of the overcurrent and is faster than the overcurrent operating time of the breaker or fuse. In one embodiment, this involves operating a current protection device in response to an overcurrent occurring for a second overcurrent duration inversely related to the magnitude of the overcurrent according to a first characteristic, and adjusting the first overcurrent duration to follow a second characteristic having variations substantially the same as the first characteristic but having a shorter first overcurrent duration than the second overcurrent duration.

Abstract: In a gas-filled arrester, a pair of main electrodes and a ground electrode are air-tightly fitted to an insulating tubular member. A springy, electrically-conductive short-circuiting element having an arcuate shape is fitted around the outer wall of the ground electrode. The short-circuiting element includes extension portions extending along the outer wall of the insulating tubular member to the respective main electrodes, and these extension portions are made to face the main electrodes by utilization of spring characteristics thereof with a certain gap maintained and with a thermally-fusible spacer interposed. With this construction, if the arrester is overheated, the spacer is thermally fused by heat and therefore the extension portions electrically contact the main electrodes due to the spring characteristics thereof. Since the main electrodes are thus short-circuited to the ground electrode, the arrester is prevented from failing.

Abstract: A thermal protection circuit for an integrated circuit subscriber line interface is disclosed. The thermal protection circuit monitors the temperature of the integrated circuit and develops an output voltage signal that shuts-down the integrated circuit when a specific temperature is exceeded. The thermal protection circuit includes first and second current networks arranged to each develop first and a second currents respectively, of substantially the same value. The second current develops a reference voltage which is applied to an output transistor. When the base-emitter junction voltage of the output transistor is less than or equal to the reference voltage, the transistor begins to operate. This increases the current flowing through the first current network which is replicated in the second current network. The increased current flowing in the second current network increases the reference voltage, thereby, fully operating the output transistor and developing the output voltage signal.

Abstract: In a method and device for limiting the starting current of a DC converter, at least one buffer capacitor is initially charged through a load resistor. The current going through the load resistor is measured with a monitor. The monitor switches on a DC converter and bridges the load resistor once a switching threshold is reached. A predetermined minimum current is used as the switching threshold.

Abstract: The reset circuit of a fault indicator is coupled to a transformer secondary winding by a cable having an elongated conductor and a resistance close to the secondary winding. The resistance is capable of withstanding a minimum transient impulse of 10 kv.

Abstract: A lamp output protective circuit for an electronic controller having a first npn transistor connected to an output terminal through which a lamp is supplied with electric power, a resistor connected between the emitter of said first npn transistor and the ground, and a second npn transistor having its collector connected to the base of the first npn transistor, its emitter to the ground and its base to a point between the emitter of the first npn transistor and the resistor. The base of the first npn transistor and the collector of the second npn transistor are connected to a signal line of the electronic controller connected to a power source.

Abstract: A protection circuit for a semiconductor circuit for protecting it from a thunder surge and overcurrent or overvoltage. A surge absorbing element and a Zenor diode are in parallel connected to the semiconductor circuit. A first fuse are connected before between the electric source and the surge absorbing element. A second fuse and a resistor, which is in series connection, is arranged between the surge absorbing element and the Zenor diode.

Abstract: A power switching apparatus is provided with a plurality of power switching elements in which each power switching element is configured to receive an input signal, a carry-in signal and two partial duty cycle signals. The power switching element is also configured to provide an output signal and a carry-out signal. A power switching apparatus made in accordance with the present invention comprises a plurality of such power switching elements associated together with each power switching element having it carry-in signal being provided by the carry-out signal of another preceding power switching element and, additionally, having it carry-out signal being associated with the carry-in signal of a subsequent associated power switching element. The combination of power switching elements provides a power switching apparatus with a plurality of inputs and a plurality of outputs wherein the plurality of outputs are generally equally distributed between two alternative wave forms.

Abstract: A short-circuit protected switched output circuit having: an input node (I10) for receiving an input switching signal; an output node (O10) for outputting a switched output signal; switch means (Q10) connected between the input and output nodes; and a Schmitt trigger NAND gate oscillator arrangement (C10, D11, D12, NG10, R12, R13, R14) having an input coupled to the output node and having an output coupled via diode means to the input node, whereby the oscillator arrangement produces a low frequency, low duty-cycle, fixed-frequency signal at the output node in the event of the output node being short-circuited. An alternative circuit using a Schmitt trigger inverter are also disclosed.

Abstract: A device which enables a self-healing capacitor with more than one group of sections in series to undergo repetitive clearing without generating the resulting potential differences between the series sections which causes additional failures. In one embodiment, the device to conduct charge is a diode and resistor connected across each group of parallel sections so as to be nonconducting when the capacitor is charged but to become conducting when a clearing event occurs. An additional aspect of the device is a method for charging such a capacitor so that no section is overcharged.

Abstract: An arrester for an under oil transformer is connected between a primary bushing lead and an insulator/isolator penetrating the wall of a housing which encloses the oil, arrester, and transformer parts. A ground wire outside the housing is removably connected to the isolator which functions as a circuit disconnector. The ground wire is removed to open circuit the arrester so that the transformer may be tested without having to disable any parts in the housing. Responsive to an arrester failure, the ground wire is blown away to give a visual indication of the failure. The blowing away of the ground wire eliminates the need for the arrester to fail in an open circuit condition.

Abstract: An automobile alternator regulator integrated circuit having a voltage-supply or -sense node (6) for connection to an external voltage, and a voltage clamp comprising: a pnp bypass transistor (Q1) having a base electrode, an emitter electrode coupled to the node and a collector electrode coupled to ground; a resistor (R1) connected between the base electrode and the node; a Zener diode (Z1-Z4) connected between the base electrode and ground for enabling the bypass transistor when the voltage at the node exceeds a predetermined value, whereby the voltage at the node is clamped to a voltage no greater than the predetermined value; and a fuse (F1) connected between the node and the emitter electrode so as to provide a subsequently identifiable cause of failure if the fuse becomes blown due to excess voltage while allowing subsequent operation of the integrated circuit if the clamp means fails but another part of the integrated circuit remains functional.

Abstract: A dimmer switch and dimmer system is described in which dimming for the entire system is controlled from a single device while on/off switching is controlled by individual devices at multiple locations. The main dimming device contains an alternate action switching circuit for opening and closing the gate circuit of a controllably conductive device. Each of the remote location switching devices consists of respective low voltage switches, each operable to operate the alternate action switching circuit in the main dimmer device and are connected thereto by wiring which carries only signal level voltages and currents. Each remote switch may be a wall-mounted switch containing a single, relatively large area push button which momentarily closes a short movement, low activation force pair of contacts when the large area push button is depressed by pressure applied to any portion over its surface.