Abstract: An electromagnetic contactor is taught which includes a conduction angle controlled triac or similar gated device which is connected in series circuit relationship with the winding of an electromagnetic solenoid or coil which is responsible for closing the contactor contacts and for keeping them closed. The current flowing through the triac is fed to a microprocessor which digitizes the current and compares it to a stored standard. The conduction angle is then decremented or incremented as necessary to change the conduction angle to cause less or more current to flow per half cycle until the amount of current flowing as sensed on a half-cycle-by-half-cycle basis is equal to the current represented by the stored standard.

Abstract: A supervisory circuit for use in an integrated circuit to supervise the program execution of a processing unit is disclosed. The processing unit generates a restart signal at a particular duty cycle under proper program execution conditions and at an undesirable duty cycle under improper program execution conditions. The supervising circuit includes a capacitive or like circuit element for converting the restart signal into a signal representative of the duty cycle thereof and compares the generated signal to a reference window comprising upper and lower reference values. Should the generated signal exceed the boundaries of the window reference, a corresponding control signal is generated to change the circuit conditions and generate a reset signal to the processing unit to govern the program execution thereof to a prespecified point from which point program execution may continue upon removal of the reset signal.

Abstract: An automatic transfer switch with time delayed emergency generator system is taught. The microprocessor is interconnected with a programming device and with a shift register whereby a countdown time is programmed into the shift register by way of the microprocessor. Furthermore, an oscillator is provided which in turn provides a continuous supply of one second countdown pulses which are normally prevented from reaching the input countdown terminal of the shift register by a disable gate which is controlled by an output signal from the microprocessor. When the microprocessor loses power which is indicative of the power from the main source disappearing, as is the situation where an emergency generator would be desired, the disable device is immediately turned off allowing the countdown pulses to reach the shift register, thus starting the one second by one second countdown operation.

Abstract: A bidirectional coupling circuit is provided for carrier based communication and control networks in which a coupling transformer is employed having relatively decoupled primary and secondary windings which are each tuned to the carrier frequency. Separate secondary windings are wound on the same core leg, one of these secondary windings being employed as a transmitter winding which is referenced to a positive supply voltage and the other winding being employed as a receiver winding which is referenced to ground. The coupling transformer is arranged to have a relatively high input impedance at the carrier frequency but due to series resonant effects has a relatively low impedance for undesired signals on either side of the carrier frequency. An operational amplifier is connected to the receiver winding to provide high gain amplification for a signal received from the common network power line without loading the other windings of the transformer.

Abstract: An analog signal processing circuit including both an analog signal multiplexer and a ranging circuit in cascade therewith is adapted for use in an integrated circuit. The multiplexer has a plurality of input current paths and an output current path. It responds to a set of coded selection signals to couple one of the input current paths to the output current path to permit current therebetween and includes another circuit for maintaining the selected input current path at a predetermined potential, preferably ground potential. The ranging circuit has its input current path coupled to the output current path of the multiplexer and includes a plurality of current splitters coupled in a cascaded chain having one end of the chain coupled to its input current path. The ranging circuit responds to another set of coded selection signals to draw current from one and another current paths to the output current path of the multiplexer.

Abstract: Starting and operating method and apparatus for discharge lamps comprises a current-limiting and rectifying means which provides at its output a low-ripple current-limited direct current. To effect lamp starting, a series-connected inductor and capacitor form a high "Q" resonant circuit with the capacitor connected across the lamp to be operated. This starting circuit connects through a blocking capacitor and charging resistor across the low-ripple source of DC. A pair of transistors which comprise an oscillator are connected emitter-to-collector across the source of DC, with the common-connected emitter and collector connected to the blocking capacitor. A drive air-core transformer has separate feedback windings in the starting and operating circuits and drive windings are associated with the transistors. A trigger diode is used to initially pulse one of the transistors which initially oscillate to generate square waves having a frequency corresponding to the resonant frequency of the starting circuit.

Abstract: Improved programming and control device for modified lead ballast for HID lamp. The basic ballast comprises a high reactive transformer and capacitor connected intermediate the transformer and lamp. An additional inductor and AC switch connect in parallel with the capacitor and the switch is opened and closed to vary the lamp current to control lamp output. The improved device comprises a parameter measuring means which measures a lamp operating parameter and converts same into output electrical signals. These signals are compared to a reference signal to generate error signals. The error signals are integrated by a capacitor and a potential which is indicative of the integrated signals is slowly developed at one capacitor terminal. A ramp capacitor is charged each half cycle of energizing potential. When the ramp capacitor potential crosses over the potential displayed at the one terminal of the integrating capacitor, a comparator means generates an output signal.

Abstract: A circuit interrupter includes a trip unit consisting of a microcomputer and a liquid crystal numeric display mounted on the front panel of the trip unit. A power supply provides operating power for the trip unit even after a tripping operation. A microcomputer includes read-only memory for storing instructions to cause the microcomputer to sequentially display numeric values corresponding to the present electrical conditions through the circuit interrupter and the parameters defining the time-trip characteristic of the interrupter. Storage means are provided to store the level of phase or ground current resulting in a tripping operation and for displaying this value following a trip. Means are also provided for displaying a single digit numeric value indicating the cause of trip.

Abstract: An optical reading system employing a commercially available line scanning camera which is sensitive to the ink employed in preprinted document formats. The sensitivity of a line scan camera to the preprinted ink formats is minimized by employing an incandescent document illuminating source, a lens system for the line scan camera which is optimized for use in the near infrared region, and an infrared pass filter positioned between the line scan camera lens system and the document to filter the light reflected from the document.

Abstract: Add-on device for lead-type ballast comprises additional inductor and series-connected controlled AC switching means which are connected in parallel circuit with the capacitor portion of the lead-type ballast such as is used to operate an HID sodium lamp. The add-on device has a sensing and control circuit which operates to sense a lamp operating parameter in order to control the actuation of the AC switching means which in turn controls in predetermined fashion the operation of the ballasted lamp. The inductor and AC switch and sensing and control means of the add-on device are all packaged within a can-shaped member which has dimensions similar to those of the conventional capacitor can for the lead-type ballast. All the elements of the add-on device are potted within the capacitor can with terminal means extending from an end portion thereof for ready connection along with an exposed potentiometer portion to enable the control to be adjusted.

Abstract: Unitary light source comprises compact HID lamp and starting and operating circuit therefor operable from household AC energizing potential. The HID lamp is ballasted by incandescent filament means which also provides the major portion of developed light during HID warm up and after power interruption. The ballast filament and input terminals of a full-wave rectifier connect in series across the light source input terminals and the HID lamp connects across the rectifier output. A low-impedance path means and high-voltage pulse generator, which includes a high-voltage electrode operatively associated with the HID lamp, connect across the rectifier input. Initially, the voltage developed across the rectifier input is relatively high and the pulse generator and low-impedance path means are responsive thereto to devleop high voltage pulses and also provide a low impedance path in series with the ballast filament to cause it to incandesce brightly.

Abstract: A circuit interrupter includes a microprocessor based trip unit having a plurality of output control lines and a power supply for providing operating power to said trip unit. Interlock means are provided to maintain the output control lines in a predetermined inactive status for a predetermined time period following energization of the power supply to allow time for operating power to rise to a level sufficient to enable the microcomputer to assert positive control over the status of the control lines. An automatic reset circuit is provided to reset the microcomputer program counter to an initialization routine unless a pulse pattern produced by proper execution of the microcomputer instructions is received by the automatic reset circuitry.

Abstract: A circuit interrupter includes a microcomputer-based trip unit, and a display and control panel comprising a numeric display device and a plurality of legends associated with light-emitting diodes. The trip unit presents a sequential display of numeric values of associated circuit electrical parameters and time-current trip characteristic setting values, with the currently visible numeric quantity being identified by an energized light emitting diode and associated legend. The control panel also includes a test switch for initiating a test operation and a potentiometer for selecting a desired simulated fault current value for the test operation. The test capability is provided simultaneously with normal circuit breaker operation which maintains full protection of the associated circuit. A short-delay feature is provided having a selectable i.sup.2 t characteristic with adjustment of both pick-up and time parameters.

Abstract: A circuit breaker includes a digital electronic trip unit having a microprocessor. The front panel of the trip unit includes a potentiometer connected across a reference voltage, and a numeric display device. The potentiometer is adjusted by an operator to enter a value of a parameter defining the time-current characteristic of the circuit breaker. An analog-to-digital converter receives the voltage supplied by the potentiometer and converts it to a digital quantity for use by the microcomputer in performing limit checks with the current flow through the contacts of the breaker. The microcomputer formats the converted digital value of the potentiometer voltage and supplies it to a front panel-visible numeric display so that the value of the potentiometer setting as interpreted by the microcomputer in defining the time-current trip characteristic is presented on the numeric display to provide real-time feedback to the operator as he adjusts the parameter value.

Abstract: A circuit breaker includes a microprocessor-based trip unit having an optically coupled data input/output system. A pulse transformer receives input pulses generated by the execution of instructions in said microcomputer and supplies these pulses to a plurality of optical isolators, thereby reducing the power requirements of the optically isolated interface system to a value sufficient to allow complete operating power to be supplied to the trip unit and the data input/output system from the sensing current transformers within the circuit breaker housing.

Abstract: A circuit interrupter includes a digital trip unit containing a microprocessor. The circuit interrupter also includes current transformers for sensing current flow through the contacts of the interrupter and for providing operating power to the trip unit. The current transformers monitoring current flow through the breaker and control potentiometers receiving operator-entered values of the product of line voltage and power factor are connected to the microprocessor to supply it with the values needed to compute real power flow through the interrupter and to display the numeric value of this power flow. The power flow is compared to an operator-entered limit value of peak demand power, and an alarm signal is generated whenever power flow exceeds the limit value peak demand. Integration capability is also provided to calculate energy flow through the contacts in megawatt hours and to present the numeric value of this energy flow.

Abstract: A circuit breaker includes a microcomputer-based trip unit, and a remote indicator unit and power supply. The trip unit includes an optically-coupled data output system and means for generating a pulse code containing cause-of-trip information and excess demand alarm information. The remote indicator unit includes an optically coupled input circuit and a plurality of light emitting diodes to indicate cause of trip and excess demand alarm information upon receipt of an appropriate pulse code pattern. The remote indicating unit also includes relays to provide control of external alarm circuitry upon receipt of cause of trip and demand alarm information. The remote indicator unit further includes a power supply for supplying operating power to the remote indicator unit and to the trip unit. The power supply is powered both from an external AC line connection and from internal rechargeable batteries.

Abstract: A circuit breaker includes a microprocessor-based trip unit and a designator circuit including a plurality of jumper positions. Each jumper position corresponds to one digit of a four digit style number specifying which of a plurality of optional functions and features are incorporated in the specific trip unit. Each jumper position is a multitap voltage divider. Selection of one tap on each of the jumper positions causes a set of four analog voltages to be supplied to the trip unit. An analog-to-digital converter converts the analog voltages to a series of digital representations which are interpreted by the microcomputer as a style number used to command execution of a discrete set of instruction groups, with each instruction group corresponding to one of the optional functions and features.

Abstract: A circuit interrupter includes a microprocessor-based trip unit, a numeric display, and a plurality of potentiometers each associated with one parameter of the time-current trip characteristic of the circuit interrupter. The trip unit provides a sequential display of the present setting values of the time-current trip characteristic parameters. Adjustment of any of the potentiometers is operable to interrupt the sequential display and to cause the present setting of the parameter associated with the adjusted potentiometer to be displayed. Adjustment of the potentiometer to either limit of its travel causes the most conservative setting value for that parameter to be selected. A hysteresis feature is provided to require a significant adjustment of the potentiometer before a different parameter setting will be selected.Although the potentiometers are continuously variable, operator adjustment thereof results in the selection of one of eight predetermined discrete values stored in the trip unit.

Abstract: A circuit breaker includes a microprocessor-based trip unit and a power supply for supplying operating power to the trip unit and the trip coil of the circuit breaker from either the internal current transformers of the circuit breaker or a plurality of external sources. The trip unit includes a numeric display for displaying a sequential series of parameter values under normal conditions. Under low-power conditions, the power supply provides pulses of operating power sufficient to enable the trip unit to execute all of its limit check functions and present a flashing display of a single parameter value.