Abstract: Apparatus for processing broadband impulses signals of low repetition rate includes a tuner for receiving broadband impulsive signals of low repetition rate and providing an output signal characteristic of the amplitude and spectral content of the received input signal. Resolution bandwidth filters coupled to the tuner output each have a different bandwidth that determines the measurement resolution and influences the sensitivity and transient response to low repetition rate impulsive signals. At least one radio frequency switch selects a resolution bandwidth filter for coupling to and associated one of at least a peak detector, an average detector and an envelope generator. A gate generator coupled to the peak detector, the average detector and the envelope generator furnishes a gating signal to each to provide a peak signal, an average signal and an envelope signal respectively during a selected gating interval. A microprocessor is coupled to the peak detector and the average detector.

Abstract: Monitoring a leakage current from an isolator for a high voltage conductor to ground includes directing the leakage current through a primary wire inductively coupled to a secondary winding energizing an amplifier.

Abstract: A group of bushings receives voltage in parallel to produce a current output from each bushing. Cumulatively combining the current outputs from the bushings vectorially furnishes a vector sum bushing current. Reference voltage devices also produce reference current outputs. Cumulatively combining the reference current outputs vectorially provides a vector sum reference current, and differentially vectorially combining the vector sum reference current with the vector sum bushing current delayed by 90° provides a difference signal representative of a bushing condition. As an alternative to the reference voltage devices, a second group of bushings may be used. In this case, a delay of 90° is not required. The invention may also be used to monitor the condition of other capacitive devices, for example, high voltage current transformers.

Abstract: Impedance of a power system adapted for operation at a predetermined line frequency is measured by providing a test signal of frequency different from the predetermined line frequency by an increment significantly less than the predetermined line frequency to provide an impedance measurement signal representative of the impedance of the power system at the test frequency. The impedance measurement signal is processed to provide a line impedance signal representative of the power system impedance at the predetermined line frequency.

Abstract: The invention features an apparatus and technique for amplifying a signal without creating a phase error. The apparatus is an active device with a restricted band width selected to include desired frequencies of operation. The apparatus includes at least one amplifier with a local feedback loop, formed by a network, constructed and arranged to exhibit a high forward gain at the operating frequencies. The amplifier and the network are constructed and arranged to provide substantially 180 degree phase shift between an input voltage and an output voltage at the operating frequencies. The apparatus also includes a signal input node adapted to introduce the input voltage to the inverting input of the amplifier, a signal output node adapted to obtain the output voltage from the output of the amplifier, and a resistive global feedback loop that connects the signal input and signal output nodes and controls the closed loop gain of the amplifying apparatus.

Abstract: A switching amplifier circuit includes a tri-state switching circuit receiving a DC voltage signal and having first electrical switches responsive to first control signals and providing a differential AC voltage waveform at a predetermined frequency alternating between a positive DC voltage, negative DC voltage and a zero voltage. The switching amplifier further includes a rectifier circuit having second electrical switches responsive to second control signals for receiving the differential AC voltage output waveform from the tri-state switching circuit and providing a desired output signal. The second control signals are applied to switch the second electrical switches only when the first electrical switches of the tri-state switching circuit are in the zero voltage state.

Abstract: The invention features power amplifying apparatus with controllable frequency characteristic of the gain. The apparatus includes a band pass network of two cascaded amplifiers and multiple resistors and capacitors arranged to form multiple feedback loops. The feedback loops stabilize the output A.C. signals and establish a predetermined bandwidth of the network. The apparatus also includes a capacitor resistor feedback loop, connected to the output of the second amplifier and input of the first amplifier, with the capacitor and the resistor selected to maximize the loop gain at a desired frequency.

Abstract: Automatic bridge balancing apparatus includes a reference impedance and a measuring terminal pair for receiving an unknown impedance. A source of a test signal is coupled to the reference impedance and the measuring terminal pair. A measuring detector is connected in series with the unknown impedance when connected to the measuring terminal pair to provide a measured signal. A reference detector is coupled to the reference impedance to provide a reference signal. A combiner combines the measured signal with the reference signal to provide an error signal. The reference detector includes an up/down counter coupled to a digital attenuator that provides the reference signal. A controller responds to the error signal to control the count in the up/down counter so that the associated digital attenuator provides a signal to the combiner that reduces the error signal so that the count in the up/down counter is characteristic of the unknown impedance.

Abstract: A current shunt device has main and auxiliary windings which are located in substantially the same position and are connected in series.

Abstract: A motion transducer includes a rotatable wheel, a drive assembly that engages a movable rod in contact with the circumference of the rotatable wheel, and an encoder that measures the rotation of the rotatable wheel and that encodes information relating to the rotation of the rotatable wheel. Linear motion of the movable rod causes rotation of the rotatable wheel, the angular displacement of the rotatable wheel being proportional to the linear travel of the rod.

Abstract: A signal is amplified with a plurality of amplifiers, each amplifier having a reference port, a reference node coupled to the reference port, and a signal port, and each amplifier being supplied by a power source with operating potential with respect to the reference node that is coupled to the reference port of that amplifier. The amplifiers are cascaded in a manner selected so that the output of a first amplifier (which receives the signal to be amplified at its input port) drives the reference node of a second amplifier, and the reference node of the first amplifier provides an input at the signal port of the second amplifier, whereby the first and second amplifiers are directly coupled together to amplify the applied signal.

Abstract: A power controller includes a full-wave bridge rectifier circuit coupled to an A.C. line by a storage inductor with two windings and a saturating inductor. The output of the bridge rectifier is connected to a D.C. output terminal for producing output voltages for a symmetrical amplifier. The D.C. potential provided by the full-wave rectifier is compared with a ramp signal having an external ramp set point related to the D.C. output potential relative to a reference potential to provide a trigger pulse for controlling the time the SCR is gated on. A balancing system selectively switches auxiliary resistances in and out to maintain a desired balance. Upon sensing a gross imbalance, the SCR is turned off. The power controlling apparatus includes isolation circuitry for creating an isolation barrier having a high frequency path and a low frequency path. The high frequency path includes a transformer having main primary and secondary windings.

Abstract: Power conversion system includes power amplifiers that receive D.C. potentials from rectifying and filtering circuitry that direct couple the power amplifiers to the conventional A.C. power lines. An output transformer couples the power amplified signal to an output terminal. A feedback network couples the output terminal to one input of a signal combiner that has a reference input terminal for receiving a reference signal. An isolation amplifier couples the output of the signal combiner to the input of the power amplifiers. The isolation amplifier has a combining network that receives on one input a signal from the input terminal coupled through a high pass filter cascaded with a transformer coupled amplifying stage and on the other input from the input terminal through an optocoupler amplifying stage cascaded with a low pass filter. The power amplifiers comprise like class B amplifiers having substantially the same gain driving the primary of the output transformer.

Abstract: Six high-current conducting receptacles are seated in a panel suitably insulated therefrom about an opening embracing an axis of a shaft protruding therethrough of a six-position detented rotary switch. Three equiangularly spaced studs support a tap select dial formed with an opening that selectively exposes one of the receptacles at a time and a central opening accommodating the shaft of a switch adapter below connected to the rotary switch shaft and maintained in fixed relationship with the rotary switch shaft and the tap select dial. The shaft of the switch adapter extending through the central opening in the tap select dial carries a knob. A connector plug may pass through the opening in the tap select dial for engagement with the exposed receptacle.

Abstract: A bridge circuit of the transformer ratio-arm type includes a feedback circuit that is responsive to the output winding of the transformer and that is connected to produce in the transformer a compensating magnetomotive force in such direction as to reduce the unbalance between the magnetomotive forces produced by the two ratio windings. The compensating magnetomotive force may be produced in various ways, as for example, an output current from the feedback circuit may be applied to either one of the ratio windings of the transformer or to a further auxiliary winding of the transformer to generate the compensating magnetomotive force.