Abstract: In an enclosed switchboard having a vertical bus bar supported by an insulating cover and unit chambers situated in front of the vertical bar and tiered one above the other for accommodating unit devices, each unit device having a stab-type connector including a tongue-shaped contact for establishing electrical contact with the vertical bus bar, the insulating cover includes a vertically extending channeled portion, the vertical bus bar includes a web in flat engagement with the front face of the bed of the channeled portion, a vertically extending protrusion protruding from the web forwardly, and a flange extending from one of the edges of the web and being in flat engagement with the inner face of one of the side walls of the channeled portion, the protrusion being positioned close to the flange so that as the contact moves sidewardly away from the protrusion it is brought into contact with the flange.

Abstract: A plasma switch comprising a substantially evacuated chamber, a generally tubular cathode disposed within the chamber, an elongated anode disposed concentrically within and projecting from the opposite ends of the cathode, the opposite ends of the cathode being substantially closed by an electrically conductive end plates, at least one of such end plates being electrically insulated from the cathode and from the anode, and circuit means for selectively connecting such end plate to the anode or to the cathode.

Abstract: A switch-arc preventing continuous current circuit for protecting pulsing contact telephone exchange switches, the circuit having a first transistor in circuit with and controlled by a control transistor, the power electrodes of the first transistor being disposed in circuit between an inductive coil of a stepping solenoid and a protected switch, a bias voltage source connected to a terminal of the protected switch by a blocking diode and a pair of resistors in series, and a metal oxide varistor in shunt across the power electrodes of the first transistor.

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: Apparatus is described for monitoring arcing of brushes used in the transfer of current signals to and from the field of a generator. Electrical signals from the brushes, which are applied to the disclosed monitor for analysis, may include brush arcing signals to be monitored and in addition high-amplitude noise spikes in the same frequency band as the brush arcing signals, the noise spikes thus masking accurate detection of low level brush arcing by conventional devices. A two-stage clipping network is provided in the monitor to raise the brush arcing/noise ratio and thus mitigate the masking effect of the noise spikes without loss of a portion of sampling interval during which arcing may occur.

Abstract: An arrangement for semiconductor power components in an installation, in which at least one semiconductor power component is placed between contact pieces and is enclosed in a housing exhibiting an insulator and connecting pieces. The arrangement includes current conductors which promote safety and prevent explosion by absorbing electric arcs formed in the installation. The current conductors are placed laterally adjacent to the contact pieces and annularly surrounding the latter, separated from the interior wall of the insulator by narrow gaps. Additional embodiments of the present invention employ reinforcing elements around the housing, and explosion guards around the housing, thereby further enhancing installation safety.

Abstract: A switch debounce circuit buffers the mechanical contacts of a double throw single pole switch into digital logic. It is essentially an active debounce circuit requiring only one wire from the switch to the circuit. The circuit includes a pair of oppositely connected inverting logic amplifiers with a resistor coupled between the output of one amplifier and the input of the second amplifier. The input from the switch is connected to the same leg of the circuit as a resistor and the output is taken from an opposite leg connecting the output of the second amplifier to the input of the first amplifier. The propagation of logic signals is effected by changing the state of the switch but contact bounce does not effect the logic.

Abstract: A supply and switching system for incandescent indicator lights is disclosed. A solid-state AC switch is used in conjunction with a current-limiting-transformer supply. The use of the current-limiting transformer protects the solid-state switch from the large current transients that are sometimes caused by failures in incandescent bulbs.

Abstract: A circuit for detecting arcing in a vacuum contactor in a polyphase system, caused by development of an air leak. A current transformer and sensing means, which may be independent of or which may work in conjunction with a conventional ground fault relay, senses the unbalanced leakage current and activates warning and protection circuits so as to prevent damage to the rest of the system. The protection system is activated or switched into a higher sensitivity mode when the vacuum contactor is supposed to be open so as to detect relatively small leakage currents. When the vacuum contactor is supposed to be closed, the system is disabled or is operated in a lower sensitivity mode so as to detect ground faults, but so as not to be tripped by normal surges and transients during operation of the system.

Abstract: This loss-of-vacuum detecting means for a vacuum circuit breaker utilizes input information derived from the current transformers of the overcurrent-sensing means typically present in medium voltage switchgear. In this overcurrent-sensing means, the current transformer secondaries for the respective phases of the switchgear are connected in parallel with each other across a shorting conductor; and in series with each secondary is the operating coil of an overcurrent relay. Connected in the shorting conductor is an "a" switch that is closed when the vacuum circuit breaker is closed and is opened when the circuit breaker is opened. Rectifying means is connected across said switch for developing a d.c. voltage when said switch is opened and one or more of said secondary windings is energized. Time-delay relay means is arranged to be energized by said d.c. voltage and is operable when the voltage thereacross exceeds a predetermined level for a predetermined minimum period following opening of said switch.

Abstract: Large current is interrupted against high voltage by a high speed mechanical opening line switch connected in series with a saturable reactor. A commutation capacitor is discharged through the closed switch against the line current to produce a current zero. Near the time of current zero the line switch is opened to produce arc free interruption. A dV/dt capacitor is paralleled around the switch to limit the rate of voltage rise. High contact speed of the line switch limits the size of the required dV/dt capacitor to what can be justified economically.

Abstract: This invention comprises a fusible resistor in a solid state relay comprising two solid state switches connected in parallel with each other, but in series with a load and a source of current. When the first of the two switches is switched on, the second switch also switches on, and conducts, supplying sufficient current to the load, thus reducing the voltage across both switches to that of the voltage drop across the second switch. Should the second switch fail to become turned on when the first switch is turned on, there will be a higher voltage across the first switch (and the components in series with it, if any) causing excessive current to flow through the first switch, resulting in its overheating and possibly fire, particularly if the switch is encapsulated. By providing a fusible resistor in the circuit of the first switch, the fusible resistor will open at such time and disconnect the first switch from the circuit, preventing a possible fire or possible damage to adjacent equipment.

Abstract: The invention is directed to an arrangement for detecting deficient operational capability in a vacuum switching vessel. The arrangement can provide a signal if a fault occurs which affects the operability of the switching vessel. Instead of a signal, a protective device alone or together with the signal can also be caused to respond. The arrangement includes a body of a material which changes its physical characteristics substantially in a limited temperature interval and is attached in heat-conducting contact with a part of the vacuum switching vessel which has a temperature time constant as small as possible. This change of the characteristics of the body acts to initiate the above-mentioned signal or action of the protective device. The invention is suited particularly for application in switchgear with vacuum switching vessels.

Abstract: Electric timing circuitry for a camera comprises a series connection of a resistor and capacitor with the junction point of the two being connected to the input of a switching circuit. A series circuit composed of a starting switch for initiating the timing cycle and a source switch for connecting the circuitry to a source of electric energy is connected in parallel with the capacitor. The single capacitor performs the dual role of functioning as a timing capacitor and compensating for switch chatter of the source switch.

Abstract: A high speed a.c. voltage regulator comprises a transformer having a plurality of switchable primary windings across which an unregulated voltage is impressed and which control the regulated voltage, and a secondary winding across which the regulated voltage is generated. During a regulation period, which comprises one cycle of the unregulated voltage frequency, peak unregulated input voltage is compared against an upward ramping reference voltage to control a source of clock pulses, where the instantaneous level of the reference voltage is related to the number of clock pulses generated during a regulation period. The number of clock pulses generated during a regulation period controls the switchable windings.