Abstract: A plurality of wire-shaped electrodes are arrayed at equal intervals within a plane insulator layer, and an electric power source for applying an A.C. voltage between adjacent ones of electrodes is connected to the electrodes via protective resistors so that an electric field in a curtain form is established between respective electrodes. The resistance value of the protective resistors between the electric power source and the electrodes and the resistance of the electrodes themselves are respectively selected higher than a minimum A.C. ignition resistance that is necessary for preventing ignition by spark discharge of powder to be processed by the curtain-like electric field. This prevents powder explosion induced by a spark discharge caused by a fault occurring in one part of the electric field curtain.

Abstract: An ink jet printer provides a nozzle for ejecting droplets of inflammable ink towards a recording surface and a charging electrode for imparting a charge to the droplets in accordance with information to be printed. Deflecting electrodes are positioned between the charging electrode and the recording surface. A deflecting source supplies the deflecting plates with a predetermined deflecting voltage. A resistor is connected between one of the deflecting plates and the deflecting source.

Abstract: A current limiter for an a.c. circuit having two FET's connected source to drain. The FET's are biased for symmetrical bipolar operation with source resistors for self-biasing. In operation one FET operates as a source follower and the other as a current source.

Abstract: a spark gap device in a high-voltage direct current interrupting device maintains a substantially constant ignition voltage by constructing the spark gap device in at least two series-connected main spark gaps connected in parallel with a voltage divider for distributing the voltage across the main spark gaps. An ignition voltage-determining auxiliary gap is connected in series with an impedance connected in parallel with one or more of the main spark gaps to effect a continued ignition thereof. The ignition voltage of the high-voltage direct current interrupting device is determined by the auxiliary gap such that the auxiliary gap is not subjected to appreciable wear whereby the variations of the ignition voltage are relatively small and not influenced by the wear of the main spark gaps.

Abstract: Power line transient suppressing circuits which use inductors in series w the load to reject or attenuate transients on the power line over a wider range of transients than with prior devices, and also serve as inrush current limiters. Two unidirectional current circulating diode-inductor loop circuits eliminate the 60Hz voltage drop across the inductors. Normal operation is not affected by the circuits, but transients are rejected by the inductors.

Abstract: A capacitor protective system involves the use of three interrelated concepts within the capacitor including a pressure sensitive circuit interrupter, a fuse, and a predetermined separation of capacitor leads along an electrode foil.

Abstract: This current limiting device comprises a normally-closed source-side circuit interrupter, a normally-closed load-side circuit interrupter, an electrical conductor connected between the interrupters for connecting the interrupters in series, and a normally-open switch that can be closed to connect the conductor to ground via a low-impedance conductive path located electrically between the interrupters. A switch operator acts to rapidly close the switch in response to a fault on the power circuit extending through the series combination of interrupters, thereby connecting the conductor to ground through the switch. The switch operator closes the switch within 1/4 cycle of power frequency current after fault inception, thereby effecting current-limiting action with respect to current through the series combination of interrupters on the load side of the conductive path to ground.

Abstract: A current limiting iron wire resistor having a transformable resistance for a current limiting circuit breaker. Each pole of the circuit breaker includes said resistor in parallel with a pair of auxiliary contacts for current limiting which are in series with a pair of main contacts to open the circuit. The main contacts are separable upon operation of a thermally and electromagnetically operable tripping mechanism, and the auxiliary current limiting contacts separate only on occurrence of a high amplitude fault current above a preselected threshold value. When that value of fault current is reached, the tripping mechanism and associated components which operate the auxiliary current limiting contacts serves to increase arc voltage almost instantaneously to that of the source, about which time the fault current is totally shunted into the current limiting resistor.

Abstract: An explosively activated current interrupter is provided for use in a fault current limiting system employing a plurality of such interrupters. Each interrupter includes an automatic switching system for sequentially installing each of a plurality of the interrupters on a power line. A conductive member in the interrupter housing conducts current carried by the power line. An explosive charge in the housing breaks the conductive member into a plurality of separated portions upon detonation, thereby interrupting the power line current. A switch opened and closed by means of explosive gas pressure alternately installs and removes the interrupter from the power line. Each interrupter is connected by a gas conduit to the next sequential interrupter to be detonated. Upon detonation of one interrupter, a portion of the explosion gases are transferred by the conduit to the next interrupter, operating the switch to install the next interrupter on the power line after an appropriate delay.

Abstract: To detect a d-c component of alternating current in the primary winding of an electric power transformer, a pair of current transducers are provided. Each current transducer has a saturable core adapted to be magnetized by the same current as flows in the transformer primary winding, and bias means associated with both transducers presaturate their respective cores in opposite directions by equal predetermined amounts of magnetomotive force. Secondary windings on the cores of the respective current transducers are connected to means for deriving an output signal in response to voltage induced in one but not both of the secondary windings as a result of alternating current containing a d-c component in the power transformer if such current has sufficient magnitude to unsaturate the core of one of the current transducers, a condition typifying the surge of inrush magnetizing current that flows in the transformer primary when initially energized.

Abstract: Disclosed is a force commutated static switch composed of inverse parallel connected thyristors. A bilateral commutation circuit is connected across the thyristors. The commutation circuit includes a switched capacitor which, during a current commutation interval, provides the dual functions of contributing to the current commutation operation and of acting as a current source for one of the thyristors. The capacitor discharge current interacts with the intrinsic resistance of the thyristor to provide a relatively low forward voltage drop which is a reverse voltage drop for the other thyristor. The low reverse voltage is known as soft biasing voltage. This voltage is utilized in conjunction with the most recently turned off thyristor to prevent reconduction thereof during the critical recovery time of the thyristor. The commutation circuit cooperates with its control circuit to provide an abort capability for its current limiting operation.

Abstract: Transient voltage overshoot is known to occur when primary current in a multi-phase X-ray generator high voltage transformer is switched on. Transient overshoot is supressed by connecting an impedance in series with the primary current switch. A second switch short circuits the series impedance after a time delay whose length is controlled as a direct function of the primary voltage and as an inverse function of the primary current.The secondary switch and time delay circuits may comprise self-powered modules which may be added to the primary circuits of existing X-ray generators without additional sensing or power supply connections.

Abstract: A low voltage protection circuit for an air conditioner compressor which employs a series of diodes to control the application of an a.c. source potential to the resistive heater element of a conventional thermally responsive switch. The diode circuit maintains the heater element directly across the source potential at all times when the thermally responsive switch is open, but only during alternate half-cycles of the source potential when the thermally responsive switch is closed to thereby protect the compressor against potentially damaging low voltage conditions while reducing the power consumed by the heater element during periods of normal source voltage level.

Abstract: Circuitry for limiting the instantaneous peak current, under fault conditions, of an AC power line, includes a high speed circuit breaker in series with a first capacitor in a main current-carrying branch, which branch is paralleled by two additional branches. According to various embodiments these branches contain various combinations of resistance, capacitance and spark gap elements whereby upon occurrence of the excess fault condition, the high speed circuit breaker opens. Thereafter the voltage buildup across the first series capacitor is sequentially commutated to a second branch having a capacitor and spark gap, with a predetermined arc-over voltage, and subsequently to a third resistive branch. The third branch effectively provides the peak current limiting impedance.

Abstract: A direct current power apparatus for control of current amplitude during overload, short circuit, switching and similar events. During normal operating conditions, current flows substantially unaffected through the windings on a pair of commutated reactors. However, when current exceeds a predetermined value, reactor flux is varied to increase the counter electromotive force within the reactors to thereby limit the output current to a safe level.

Abstract: In a touch sensitive electronic switching circuit including a C-MOS inverter, for use in electronic wristwatches, a resistor of 1-10 M.OMEGA. is connected to the source electrode of the P-channel MOS type field effect transistor included within the C-MOS inverter, whereby the threshold voltage level of the C-MOS inverter is shifted to a low level to enhance the reliability of the touch sensitive electronic switching circuit. In another embodiment, the resistor of 1-10 M.OMEGA. is connected to the source electrode of the N-channel MOS type field effect transistor included within the C-MOS inverter, whereby the threshold voltage level of the C-MOS inverter is shifted to a high level to enhance the reliability of the touch sensitive electronic switching circuit.

Abstract: A current limiting network is connected in a power line between an AC power supply and a load, and has a pair of series connected resonant branch circuits, each of which include a capacitance and an inductance tuned to the power supply frequency. Under normal operation virtually no impedance is offered by the network. Each branch circuit has a circuit node between the capacitor and inductor contained therein. A switch, having a resistance in series therewith, is connected between the circuit nodes in the branch circuits. The branch circuits are connected in parallel, and a resistance is connected in parallel with the branch circuits. The switch is responsive to a fault current in the power system and when actuated, detunes the series resonant branch circuits to thereby present a high impedance to the power line. The parallel resistance reduces the level of any transient surges and the time of any oscillation appearing on the capacitors when the switch is actuated by a fault current.

Abstract: High-voltage interconnection circuit-breaker, having connected in parallel, in the first instance a main chamber, having a cut-out power, comprising a rapid functioning on opening and provided for an opening-closing cycle; in the second instance a very rapid closing chamber having a closing power and resistance to overcurrents which lasts a very short time; and in the third instance in series, a resistor and a cut-out chamber for the current reduced by the resistor.

Abstract: A bi-directional data transmission system in which the magnitude of the data signals transmitted from a data device is monitored and data transmission to and from the data device is interrupted when the magnitude of the signal exceeds a pre-selected level is disclosed. The system includes a protective network coupling a data device and a data transmission circuit. The protective network includes a conductor providing a path for data signals which enter and leave the data device via the transmission circuit. A control circuit is positioned in the data path for receiving the data signals entering and leaving the data device via the transmission circuit and for providing a binary control signal which is dependent solely on the magnitude of the data signal leaving the data device.

Abstract: An overload circuit for a loudspeaker system which indicates the overload and also automatically reduces the load on the speaker system to prevent damage in which a rectifier followed by a smoothing circuit is connected in parallel with the speaker and supplies an output to a magnetic coil for energizing a magnetic switch on overload so as to place a load dropping means in series with the speaker during overload. The load dropping means might be a lamp which visually indicates the overload condition.

Abstract: A current-limiting device for an alternating current system has for each phase a pair of saturable reactors each with an iron core, an alternating current winding and a superconducting direct current bias winding which is common to the reactor cores and biases them both to saturation. The two alternating current windings in each phase are connected in series opposition such that under fault conditions they are driven out of saturation on alternate half-cycles and thus limit the overload current. The superconducting winding has a surrounding magnetic flux screen which also forms a loop for shunting alternating current under fault conditions and which may be used as a direct current control circuit for varying the bias level. The screen serves as the outer vessel of an evacuated enclosure for the superconducting winding and a suppot system for the inner vessel is also described.

Abstract: There is provided a protection system for an inductive load of the type having a ferromagnetic core. The system is comprised of a current limiting resistance serially coupled to the load. A zero crossover detection device, having an input and an output, is adapted to couple an A.C. voltage source to the load when the A.C. voltage is at or near the zero crossover point in its cycle. A switch having an open and a closed state is connected in shunt across the current limiting resistance and is actuated by the output from the zero crossover device so as to maintain the switch in an open state during an initial portion of the A.C. voltage cycle.

Abstract: A current limiting and fault indicating circuit for connection between a load and a source of electrical current including a pair of tungsten lamp filaments connected in parallel. The lamp filaments are chosen so that the current drawn by the load during the normal operation of the load produces only a small voltage drop. In the event of an overload or a short circuit, however, the increased current flow through the lamp filaments will heat the filaments to incandescence and the non-linear increase in impedence will absorb the source voltage and indicate the circuit to malfunction by the emission of bright light. The current flowing as a result of the fault will be limited to the rated current of the lamps.

Abstract: In a touch sensitive electronic switching circuit including a C-MOS inverter, for use in an electronic wristwatch, a resistor of about 5 M.OMEGA. is connected between the gate electrode of the C-MOS inverter and an input terminal associated with a touch sensitive electrode formed on a preferred position of the casing of the electronic wristwatch. The resistor of about 5 M.OMEGA. functions to prevent the C-MOS inverter from being damaged by an erroneous application of a high voltage to the touch sensitive electrode.

Abstract: An encapsulated intrinsic safety electric barrier in which at least one positive temperature coefficient resistance device is embedded in the insulation together with the other electrical components of the module.

Abstract: A circuit for connecting a loudspeaker combination having a treble loudspeaker to an amplifier with a control device for emphasizing the amplification in the range of the treble frequencies, comprising a positive temperature coefficient resistor connected in parallel to a fixed resistor. The parallel resistor combination is connected in series in the electrical connection means for the treble loudspeaker and substantially through the first-mentioned resistor has a value which during normal operation of the loudspeaker combination is smaller than that of the treble loudspeaker, and further has a temperature coefficient such that by exceeding of a permissible constant load voltage for the treble loudspeaker, its resistance value increases with respect to the treble loudspeaker such that the latter is not thermally overloaded. The fixed resistor limits the resistance increase of the resistor combination to a predetermined value.

Abstract: A resistor with a heat sink, particularly adapted for use as a current limiter in an electrical system, such as a power transmission system. The resistor comprises a hollow tube formed of metal which offers resistance to the passage of electrical current, the tube being of a length sufficient to provide the electrical resistance for a given application. The heat sink comprises a material having a high specific heat, the material being contained within the tube and adapted to absorb heat generated by the resistance of the tube to passage of electrical current.

Abstract: A protective circuit comprises a metal-oxide-semiconductor field effect transistor (MOSFET) to be protected, and a depletion-type MOSFET the gate and source of which are connected to each other and the souce of which is connected to the gate of the MOSFET to be protected, whereby the protective circuit which is suitable for a high-speed operation is completed.

Abstract: An MIS switching circuit capable of enduring a high voltage, comprises a switching FET, one or more protective FETs connected in series to the switching FET and a load connected between the drain of the protective FET and a high voltage source, wherein the load is constituted by a series connection of a plurality of FETs.

Abstract: Apparatus for overvoltage protection of a direct converter utilizing controllable semi-conductor valves and whose output is connected to the rotor circuit of an asynchronous electrical machine includes a stepped impedance circuit which is controlled by a stepped current valve switching circuit. The stepped impedance circuit is connected to the output terminals of the converter and the valves of the switching circuit are controlled in accordance with the amplitude of any transient overvoltage induced in the rotor circuit in such manner that the total resistance value of the impedance circuit varies inversely with the amplitude of the overvoltage. The impedance switchable into and out of the circuit can be arranged in series, or in parallel, or in series-parallel.

Abstract: A method and apparatus for reducing the mechanical stresses on the shaft of a turboset and on the shaft of the generator coupled thereto upon the occurrence of a three-pole mains short circuit near the generator and upon the subsequent elimination of the three-pole short circuit. A generator switch is connected between the output of the generator and the mains, and a resistor, whose size is adapted to the size of the load on the generator, is connected in parallel with the generator switch. The generator switch is opened upon the occurrence of a short circuit to switch the resistor into the load circuit of the generator and the resistor is again bridged when the short circuit is switched off of the mains.

Abstract: An improved electrical power supply system is disclosed for preventing arcing between two or more electrical machines energized by a common power source with at least one of said machines receiving power through a lengthy power cable, said cable having a grounding conductor connecting the external conductive housing of said machine to earth ground. A unique multi-winding transformer is connected between the common power source and the cable, so that arcing attributable to voltage induced in the cable grounding conductor is limited to non-dangerous current levels by an inductive impedance from a first winding of the multi-winding transformers, which winding in series with the cable grounding conductor. However, under short circuit conditions, another winding of the multi-winding transformer overcomes the inductive impedance of the first winding so that the current carrying capacity of the cable grounding conductor is no longer limited by the impedance of the first winding.

Abstract: The gate of an IGFET, which is directly connected to the input terminal of a circuit is protected by means of first and second diodes connected between the gate and first and second points of operating potential, respectively. The first diode is poled to conduct current in the forward direction when the potential at the gate is more positive than the potential at the first point and the second diode is poled to conduct current in the forward direction when the potential at the gate is more negative than the potential at the second point. A high conductivity diode means is connected between the first and second points of potential. The reverse breakdown voltage (V.sub.R) of the first and second diodes is greater than the V.sub.R of the diode means whereby the first and second diodes conduct only in the forward direction while the diode means conducts in the forward or reverse direction.

Abstract: A step-up transformer is connected to a reference potential level and is coupled to a multiple-electrode gas-filled discharge tube to provide a pulse of sufficient magnitude to fire the tube and thereby protect a signal line and the equipment to which it is connected against voltage surges which may be harmful but which are otherwise too low to ignite the tube.