Sigma Instruments, Inc.

Thomas E Beling

Leopold Bric

Florian F Yanikoski

Thomas I Marx

John O Morin

In a power distribution system, in order to maximize efficiency and to provide protection in the event of a lightning strike or other transient, a fiber optic drive is utilized to transmit measured parameter signals through a fiber optic link to a control system. The fiber optic drive is powered only in timed, short bursts at ten second to ten minute intervals with a power supply that capacitively draws small amounts of energy over the long intervals and energizes the drive with accumulated high power pulses.

Power transmission systems and means for control thereof

In a power distribution system, power line insulators have three electrodes, two of which are connected to the line and to ground, and the third of which forms a capacitively stepped down voltage corresponding to the line voltage, and use sensing coils to measure current. The sensing coils are inversely connected and differentially located to suppress noise.

Power distribution systems and means for control thereof

In the disclosed system, recurring signals, such as from a watt-hour meter or other type of meter, are registered, by sensing the signals, converting the signals to mechanical motions, and applying them to a mechanical register so that the register accumulates the motions sensed by the amplifier and indicates a value representative of the accumulated total of the signals. According to one embodiment of the invention, a sensor senses the signals formed by gaps in the rotating disc of a watt-hour meter and an amplifier drives a stepping motor on the basis of the signals. The stepping motor advances an odometer whose non-volatile output can be read visually or scanned electronically over a telephone line.

Signal reading system such as for remote reading of meters

In the disclosed measuring system, the strain in opposingly stressed strain gauges is measured by alternately driving currents through the gauges, and measuring the resulting differences in the alternate currents. Two reversely poled transistors, or two FETs, form low impedance switches that alternately drive the currents through the gauges. A constant current source or a resistor provides a current path to both gauges.

Strain gauge measuring system

In the disclosed system, if the frequency of input signals exceeds a value suitable for a load, the input signals and output signals are stored and compared in a comparator while locking of a phase locked loop is delayed by a loop filter that allows the output of the VCO (voltage controlled oscillator) to increase or decrease only at rates slower than given rates. When the input signals end after the loop locks, the filter delay causes the VCO to keep producing signals which are passed until the comparator recognizes that the number of output signals equals the number of input signals. If the input signals end before the loop locks, a logic circuit causes the VCO frequency to keep rising until another comparator indicates that the number of output signals has reached one-half the input signals.

Phase locked loop control system

A synchronous motor is driven by applying cyclical or digital data through a phase locked loop whose loop filter integrates with a time constant equal to or greater than the inertial delay of the motor from start to its operating speed. According to one embodiment, the frequency output of the phase locked loop is further controlled with a digital rate multiplier whose phase effects are minimized by operating the VCO at a multiple of the input frequency and feeding the VCO voltage back through a frequency divider. According to another embodiment, the frequency control is obtained with a preliminary phase locked loop with a normal filter but a high frequency VCO whose feedback is divided by a value n, and then dividing the output of the main loop by m. Suitable counters may be used to stop and start the drive.

Synchronous motor drive

In the disclosed circuit, a bilateral breakdown switch such as a triac includes two terminals for connecting an AC source to a load. A variable input arrangement, such as one which includes an LED and a photoresistor, operates a control electrode on the switch to turn the switch on and off in response to an input signal. The switch is disabled when the momentary AC voltage exceeds a predetermined value. This is done by a sensor that senses voltage and a bilateral switching arrangement that responds to the sensor and turns off the switch in response to a voltage higher than a predetermined value. According to one embodiment, the bilateral switching arrangement is composed of two complementarily poled transistors connected in parallel with respective bases connected to the sensor. Series diodes provide unidirectionality for the transistors. Back-to-back parallel diodes connected to the control electrode compensate for the voltage drop caused by the series diodes.

Switching circuit for connecting an AC source to a load

The disclosed apparatus operates a load in one mode in response to one cyclically occurring event and in a second mode at a specified time in the cycle regardless of the phase of the one event in the cycle. According to a specific embodiment, the apparatus turns on lights at sunset and turns them off at a later nighttime hour, preferably the same hour each night. A generator stores signals in an accumulating memory at one rate during daylight hours and at a faster rate, preferably twice the daylight rate, during nighttime hours. When the memory content reaches a preset level during the night, it turns off the switch that had turned on the lights at sunset and empties itself of storage until sunrise.

Condition operated load control

Knitting-machine guide bars, which carry columns of guides through and then along a row of knitting needles and are moved longitudinally along the row on the basis of the content of a programmable read-only memory. Stepping motors which respond to the memory rotate pinions in directions and numbers of steps determined by the memory. Racks engaging the pinions articulate respective adjustable-leverage levers which reciprocate the separate guide bars longitudinally along the row. Respective springs press each rack against each pinion transverse to the rack length so as to eliminate slack. Longitudinal movement of the bars is synchronized with their transverse movements through the needle row by sensing when the guides clear the front of the needles and producing a synchronizing pulse that gates appropriate signals from memory buffers to the motors; and producing a synchronizing pulse on a separate channel when the guides are clear of the rear of the needles. Braking means brake the motors with torques of about 50% of the maximum motor torques.

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Saxonville, MA, United States of America

Thomas E Beling