Abstract: A normally ungrounded power system for a oil well is provided which includes a power transformer above ground and a pump motor below ground. There is provided a signal system which includes a below ground sensor system and an above ground signal conditioning and monitoring unit where the sensor system utilizes the main power lines for carrying the sensor signals. A connectable high resistance grounding scheme is provided to the aforementioned floating system, so that in the event of a arcing ground fault or similar occurrence the system may be immediately grounded, thus compensating for the effects of the arcing ground fault and providing personnel safety and electrical equipment protection. When the high resistance grounding system is not utilized the aforementioned signals from the sensors are easily carried by the power conductors.

Abstract: An electronic control circuit (10) for a gas oven including a hot surface igniter (24) which is heated through the application of electrical current to a temperature sufficient to ignite gas supplied through an electrically actuable gas valve (26). The applied current is regulated by a micro-controller (20) which controllably gates on a triac (14) while taking into consideration a sensed current level.

Abstract: A control and panel assembly using a thin dielectric carrier strip upon which a sheet of conductive material is adhesively attached. The conductive sheet is perforated to form an array of spaced parallel discrete conductors. The conductors are initially formed as interconnected by transverse webs which are frangibly removed after attachment to the carrier. Individual stand up connectors are then attached to each of the conductors to form a carrier sub-assembly and the terminals are inserted through slots in a dielectric deck plate. Individual user actuated control components are then plugged directly into the terminals with user actuated shafts or levers extending through deck plate and carrier strip.

Abstract: A power tool has a variable speed control circuit that comprises a user switch, a motor and a thyristor connected in series between a pair of power supply terminals. A manually variable resistor is connected between a first electrode of the thyristor and a circuit node. A capacitor is coupled between the circuit node and the second thyristor electrode. A bleed-off resistor is connected between second thyristor electrode and the circuit node to provide a path for discharging the capacitor when the user switch is open. A semiconductor trigger device, such as a diac or silicon trigger switch, couples the circuit node to the thyristor gate electrode. The circuit operation ensures that the capacitor charges from substantially the same voltage level at the start of each half-cycle during which the thyristor is to be turned on.

Abstract: A remote control residential and commercial lighting and appliance branch circuit breaker provides both overload current protection and load management. Structure is provided enabling packaging in a three-quarter inch width case, including a first set of contacts in the case provided by a pair of separable overload breaker contacts, trip structure in the case for causing separation of the overload breaker contacts in response to overload currents therethrough, a second set of contacts in the case provided by a pair of switching relay contacts having open and closed conditions and electrically connected in series with the overload breaker contacts, and an actuator in the case energizable to mechanically actuate the switching relay contacts. Feedback circuitry is included providing status indication of the condition of the switching relay contacts. Structure is provided for reducing actuator and spring requirements and sizes.

Abstract: A soft start tool handle trigger switch circuit (10) applies voltage from an AC source (12) to a portable tool electric motor (10). A current limiter (30) is connected in series between the AC source (12) and motor (14). A first sub-circuit (32) is connected in parallel with the motor (14) and includes actuator circuitry (34) tripping an actuator solenoid (36). A second sub-circuit (40) is connected in parallel with the current limiter (30) and has a pair of contacts (44, 46) actuated from an open condition to a closed condition upon movement of an actuator plunger (38). An NTC thermistor (48) is connected in series with the actuator circuitry and is physically proximate and heated by heat from the current limiter (30) to reduce the resistance of the NTC thermistor (48) and supply increased current to the actuator circuit (34) for earlier closing of the bypass sub-circuit (40), to stop the current-induced heating of the current limiter (30).

Abstract: A hybrid switch (2) having a solid state circuit (2a) including a thyristor (SCR) for closing and reopening a supply circuit (S,4,6) to a load (L) and contacts including an isolating contact (S1) for connecting power to and disconnecting power from the solid state circuit (2a), a control contact (S2) for initiating turn-on and turn-off of the thyristor (SCR), and a bypass contact (S3) for shunting the solid state circuit (2a) after the load has been energized. A zero voltage crossover circuit (ZVC) allows turn-on of the thyristor (SCR) only when the A.C. supply voltage is below a preset value to avoid arcing at the contacts on closing. The inherent zero current crossing turn-off characteristic of the thyristor (SCR) avoids arcing at the contacts on opening.

Abstract: A dual mode power transistor circuit is provided for optimizing ON state dissipation, base drive requirements, and switching speed in applications subject to large overload currents for short periods of time. The circuit has dual modes or regions of operation: (1) rated current and below; and (2) overload current. In the overload region, additional base drive is supplied to the bipolar power transistor while also keeping such transistor in its active region, out of saturation, to enable fast turn-off. The additional base drive is supplied at a given sensed current-induced threshold voltage and enables the transistor to conduct increased collector current therethrough, which in turn reduces the otherwise increased collector to emitter voltage. Turn-off power dissipation is substantially reduced, in spite of the increased collector current, due to the drastically reduced collector to emitter voltage. Particularly simple dual mode Darlington-like transistor circuitry is disclosed.

Abstract: An AC transistor switch is provided with simple, accurate and fast overcurrent protection circuitry. A pair of transistors are connected in anti-series across an AC load line, and each transistor has an anti-parallel diode therearound conducting current in the alternate half cycles. Comparator means senses current flow through the diodes and is responsive to given threshold overload current to turn off the transistors. Voltage sensing means is referenced to a common point between the series connected transistors and senses the voltage at each main terminal relative to the common point to thus sense the voltage drop from the common point across each diode to its respective main terminal for sensing current flow through the respective diode.

Abstract: An A.C. overload current sensing, remote power controller of minimum size and weight and integral construction. Current rate sensing wound toroids are used that are small enough to fit around the line terminal studs without having to enlarge the prior insulator space available therein. The electronic overload current detecting and tripping control circuit is replaced by a pair of modules, detector and control modules, having improved performance and a shape and size such that they fit within the relay housing alongside its operating magnet. The detector module has integrator means for converting current rate of change signals into current magnitude indicative signals thereby enabling use therewith of rate sensing wound toroids of about one-tenth the size of equivalent current transformer wound toroids.

Abstract: A frost sensor circuit which employs a thermistor (10, 20) to sense the amount of frost present on the cooling coils of a refrigerator, air conditioner, or the like, and to inhibit defrosting that would otherwise occur at regular intervals, in those cases where the frost present is not enough to justify a defrost function thereby to limit defrost heating to those cycles requiring it, thus saving electrical energy. This is done by mounting the thermistor at or on the coils to collect the same amount of frost as the coils and to have the defrost cycle control (11) energize the same for a timed interval, melting the frost thereon and thereby determining the amount of frost build-up.

Abstract: Various circuits and combinations of radiant energy responsive transducer means such as photovoltaic diodes connected to the gate of a depletion mode FET whose source and drain are connected to the gate and cathode of a thyristor, are disclosed to provide a semiconductor switch which is triggered into conduction solely by a small amount of radiant energy, without the need for a second triggering energy source, and which also affords immunity to unwanted dv/dt and temperature induced turn-on. Various modes of operation are disclosed, including the thyristor self-triggering into conduction, and/or being of the light-activated type itself and being directly triggered by impinging light, and/or being triggered by the light-responsive diode bias, and/or being triggered by a small bias supplied from a second set of photovoltaic diodes connected to the thyristor gate. Other combinations are disclosed providing zero-cross firing.

Abstract: A preassembled self-contained fiber optic module is disclosed which may be inserted in standard switch enclosures to enable a remote electrical switching function to be performed by means of optical switching within the switch enclosure. A single module mounts facing ends of two fiber optic cables in spaced substantially colinear alignment and also forms a narrow elongated guiding channel perpendicular to the colinear axis of the cables and intersecting the gap therebetween for guiding an operator-driven opaque shutter which is movable into the gap to block the optical path between the facing ends of the cables. Transducer means are provided at the remote ends of the fiber optic cables to supply an electrical signal in response to optical transmission. A fiber optic limit switch and a fiber optic pushbutton switch are specifically disclosed.

Abstract: A fiber optic reed switch is disclosed. A pair of fiber optic cables are mounted to the ends of cantilever reed arms by means of supports providing coaxial alignment of the cables upon closure of the reed arms to complete an optical circuit.

Abstract: A chopper for adjustably controlling the average value of the voltage supplied from a D.C. battery source to a motor load for adjustable speed control. The chopper comprises manually-operable spring-biasing means for applying force to close a contact to energize the motor and electromagnetic means simultaneously energized for re-opening the contact. This occurs at a high repetition rate so that the average value of the voltage across the motor determines the motor speed. This average value of voltage is proportional to the closed-to-open time ratio of the contact and is adjustable by manual control. Two versions are disclosed. In the first version, the spring-biasing force is applied to the contact by depressing a trigger. In the second version, the spring-biasing force is applied to the contact by rotation of a knob. Both versions may use either tension or compression spring force.

Abstract: A fiber optic reed switch is disclosed. A pair of fiber optic cables are mounted to the ends of cantilever reed arms by means of supports providing coaxial alignment of the cables upon closure of the reed arms to complete an optical circuit.