Abstract: A pair of MOSFET power transistors are connected in a push-pull configuration to drive a tapped transformer and a load. A pair of diodes and an energy coupling circuit containing a capacitor and resistor in parallel bias the transformer primary in such a manner as to limit transients in a nonconducting MOSFET when the other MOSFET is conducting, aided by a drop in voltage at an inductor (ferrite bead) network which develops at the moment of MOSFET transistor conduction. This is due to a momentary change in the impedance ratio.

Abstract: An analog signal processor used within a static trip unit is provided with an A/D converter, a digital processor and an electrically alterable non-volatile memory (EAROM) for providing trimming and calibration facility to the trip unit. The EAROM provides the ability to store parameters calculated by the user during the manufacturing process of the trip unit. Key measured or environmental variables are created and a correction algorithm is generated and stored along with data. The trip unit is then capable of self-calibration by applying the correction factor to compensate for variations in the component sensitivity. In one application, the current sensing transformer is precalibrated and provided with a correction factor and a correction algorithm. In another application, the thick film resistors within the long term trip mode network, the short term trip mode network and the power supply voltage regulator are "trimmed" by means of stored correction values.

Abstract: The individual elements of an elongated array of fluid jet orifices are independently positioned with respect to the individual elements of a second elongated array of individual charging electrodes thus relaxing critical mechanical manufacture and assembly tolerances therebetween. The number of fluid jet orifices is substantially greater than the number of independent charging electrodes so as to permit this independent positioning and the enhanced printing resolution of the apparatus is made possible primarily by the lesser density of individual electrodes in the electrode array.

Abstract: A tactile array sensor comprises an array of substantially parallel row conductors disposed upon an alumina substrate. An array of substantially parallel column conductors overlies the array of row conductors and a layer of insulative material is disposed between the row conductors and the column conductors. A conductive rubber sheet overlies the column conductors. A multiplexing circuit addresses the row and column conductors and, when an object is in contact with an area of the conductive sheet, the circuit generates output signals indicative of all crossing points within the area, due to electrical contact being made between the row and column conductors via the conductive sheet.

Abstract: Electrostatic spraying apparatus e.g. for graphic work, having a hand or finger held body carrying a nozzle to which the atomizing potential is applied from a high voltage generator. The nozzle is of the non-drip type, e.g. a capillary bore or a felt- or fibre-tip so that no liquid is dispensed therefrom in the absence of the atomizing potential. The nozzle and liquid reservoir may be a cartridge, e.g. a felt-tip graphic marker. The generator may be within the body so as to provide a self-contained unit which can be "earthed" via the user's hand.

Abstract: The invention relates to apparatus and an arrangement for starting and protecting an electrically driven motor-compressor unit. A protector switch and a PTC resistor have a common housing with a bore and slot construction adapted for clamping the housing to the external pressure tube of the motor-compressor unit.

Abstract: A generalized real-time thermal model of an induction motor produces values indicative of the transient and steady state temperature condition of the motor. Each of these values is compared with respective predetermined limits and power to the motor is removed when any value exceeds its respective limit in order to prevent damage to the motor.

Abstract: A self-contained fused unit for the protection of electrical appliances against damage caused by abnormal power surges is disclosed. Fuses are selected so that the proper amperage required to operate any appliance can be delivered through the power surge isolator while full protection of the appliance against abnormal power surges is provided. Varistors connected between terminals of the device augment the protective action of fuses in the event that certain kinds of power surges are encountered which are so fast that fuses may not blow in time to protect the appliance. In such cases, the instantly decreased resistance in the varistors assures grounding of the excessive current without damage to the appliance occurring.

Abstract: A modular electronic system is constructed by the interconnection of modules containing individual circuits. Each module includes a set of contact pads disposed at sites which are predesignated for the interconnection of corresponding terminals in the various circuits, which terminals are to be interconnected upon assembly of the system. The contact pads are disposed on the exterior surfaces of the modules and in a predetermined arrangement so that all electric connections can be accomplished unambiguously and only upon proper alignment of the modules. Activation of individual circuits may be delayed until completion of assembly by use of a sensing circuit in each module which determines that assembly has been completed or, alternatively, a displaceable connecting plate mounted on a resilient surface may be employed for springing out of connection when the modules are displaced from each other and making connection for activation of the circuits when the modules are contiguous to each other.

Abstract: A method of and an apparatus for activating an electromagnetic positioning means or actuator of the kind sometimes known as an electrical cam with relatively low currents, by alternately energizing, or energizing with currents of opposite polarity, two electromagnets to move an armature positioned therebetween between two terminal positions. The device is activated from an inactive or passive to an active state by energizing currents having at least initially a frequency greater than the resonant frequency of the positioning means. With increasing oscillations of the armature the frequency of the energizing current is reduced to zero as the device reaches its fully activated state, i.e. when the armature has oscillated in a step-like manner to one of its terminal positions. The device may be have utility for driving gas exchange valves of internal combustion engines.

Abstract: There is disclosed a coaxial lightning arresting structure comprising an inner conductor, an outer conductor surrounding the inner conductor and an arrester tube located between the inner and outer conductors perpendicularly to the direction of transmission and connected at its ends to the inner and outer conductors, respectively. The portion of the outer conductor provided with the arrester tube has an equivalently substantially increased inner diameter as compared with the other portions of the outer conductor so that the ratio of the inner diameter of the outer conductor portion having said increased diameter to the inner conductor outer diameter is greater than the ratio of the outer conductor inner diameter at the other portions thereof to the inner conductor outer diameter which latter ratio provides the coaxial transmission line with a given characteristic impedance.

Abstract: An automatic current lead retraction system for superconducting magnet installations. An automatic current lead retraction system utilizes an operator wherein either hydraulic or pneumatic cylinders bring about electrical contact of the current leads or the separation thereof as well as a safety shorting switch for the system. By using the pneumatic or hydraulic cylinders and all non-magnetic materials, there is no influence upon the magnetic field created by the superconducting magnet. Provision is made to monitor the condition of the magnet to be certain that it is in a persistent mode before the current leads are retracted. Furthermore, safety signals are generated to assure that no current is flowing at the time of retraction, that the resistance across the contacts is sufficiently low when engaged and that all electrical, air/hydraulic fluid systems are functioning properly before operation of the retracting system. Overall control is achieved using a microprocessor.

Abstract: Electrode holder system for electrothermic smelting furnaces comprising current clamps for conducting electric current to an electrode and hydraulic cylinders for moving the electrode up and down. The cylinders are connected to the electrode via an electrode frame and releasable clamping means. At least two vertical rails are arranged parallel to the electrode. The rails are at their upper ends suspended from a suspension frame and have a stopper means on their lower ends. The stopper means represents the lower limit for the movement of the current clamps. The electrode holder system combines regulation of the tip position with automatic feeding of the electrode.

Abstract: A microminiature switch for digitizing different-valued external conditions, such as pressure, temperature of acceleration, is disclosed. The switch includes a silicon wafer having a deflectable, reduced-thickness membrane adapted to move from a relaxed position toward increasingly flexed or bulged positions in response to greater-value changes in such external condition. Movement of the membrane from its relaxed position to more strained positions establishes electrical contact between a common terminal and first one and then progressively more switch-state terminals in the switch, wherein the number of switch states which are closed corresponds to the external condition acting on the switch.

Abstract: Positive and negative ion contents of the air within a region are controlled to suppress build-up of electrostatic charges on objects or for other purposes with one or more air ionizing units each having a positive high voltage generator coupled to a first ionizing electrode and a negative high voltage generator coupled to a second spaced apart ionizing electrode. The positive and negative high voltage generators are operated alternately with off times being provided between each period of ion generation of either polarity and the preceding period of generation of ions of the opposite polarity. The off times enable ions of each polarity to disperse outwardly for a controlled distance before substantial intermixing and mutual neutralization takes place.

Abstract: A current monitoring circuit of a ground fault detector which receives its input from the secondary winding of an annular core transformer through which extends the current carrying leads being monitored. A resistor and capacitor are connected in series between the secondary winding and an AC amplifier to form an RLC band pass filter to minimize the circuits sensitivity to noise outside of the band of frequencies of interest. The sensitivity of the circuit to temperature changes due to fluctuations of the inductance is reduced by choosing an inductance value sufficiently high to ensure that it is not reduced to below a critical level at which sensitivity is effected.

Abstract: A pulse power supply for generating extremely short pulse high voltages comprizing an ac charging high voltage, rectifier, pulse forming unit as a capacitive energy storage element, and an externally-controlled high speed synchronous switching unit, such as a mechanical synchronous spark switch of rotating type. The capacitive energy storage element, i.e. condenser is charged up by the ac charging high voltage source from zero voltage to its peak voltage through the rectifier without the use of current limiting resistance during its half cycle or desired polarity, i.e. negative one. Then, this charged potential of the capacitive element is kept, with the blocking action of the rectifier, until a desired instant of the next half cycle when the said switching unit is triggered from outside, e.g. by rotation of the rotor disc carrying the spark electrode elements, and the very short pulse high voltages are produced at this instant at the output of this pulse power supply.

Abstract: An AC power line transient suppression circuit comprises a bi-directional series breakdown element in combination with a series inductor and a shunt capacitor.

Abstract: An overload relay is provided which monitors current flow in a circuit and triggers an electromagnetic interrupter to open the circuit upon detection of an overcurrent condition. A train of pulses is generated and received by the electromagnetic interrupter for maintaining the circuit closed. The pulse train is terminated upon detection of an overcurrent condition.

Abstract: A current differential pilot protective relay apparatus for multi-terminal high-voltage, three-phase alternating current transmission lines. The pilot protective relay system provides comparison, at each terminal of the transmission line, of the currents flowing on each phase of the three-phase transmission line at each terminal thereof. A novel scheme of summing the current-derived signals at one terminal reduces the number of receivers and transmitters necessary to send the local signal from each terminal to all of the other terminals. Instead, the current-derived signals are summed at one of the terminals and the sum signal is then transmitted to each of the other terminals.