Abstract: A PC computer monitors the energy consumed at a plurality of local stations placed behind the electrical meter of the utility company for individual billing of the local users, a bidirectional communication line being used therebetween. A command from the PC computer causes at each station the totalized energy to be stored, and thereafter the PC computer derives individually the results for separate estimations and central billing.

Abstract: A PC computer monitors the energy, power, voltage, and current consumed at a plurality of local stations placed behind the electrical meter of the utility company for individual billing of the local users, a bidirectional communication line being used therebetween. A command from the PC computer causes at each station the power, voltage, current and totalized energy to be stored, and thereafter the PC computer derives individually the results for separate estimations and central billing.

Abstract: An integrated circuit incorporating an analog-to-digital (A/D) conversion subsystem having a current mode in which only negative analog currents are converted and a voltage mode in which only positive analog voltages are converted is adapted to produce bipolar digital current and voltage signals. An on-board microprocessor operates the A/D conversion subsystem to perform a conversion in the current mode. If the converted digital value is non-zero, this value is used as the negative digital value of analog input signal. If the result of the conversion in the current mode is zero, a second conversion is made in the voltage mode and used as digital value with a positive polarity. An input circuit having an output impedance substantially equal to the "full scale equivalent" input impedance of the IC defined as the full scale voltage of the IC divided by the full scale current, eliminates the need for special scale factors to correlate the positive and negative conversion values.

Abstract: A hybrid monolithic IC that is standardized for controlling various types of electrical equipment, such as circuit breakers, motor controllers and the like. The IC is a hybrid monolithic IC, fabricated in CMOS technology, The shortcomings of utilizing CMOS technology for linear or analog circuitry is overcome by the implementation of the IC to provide a monolithic IC that is relatively less expensive than using multiple ICs or a single IC fabricated from biCMOS technology.

Abstract: The invention relates to a bi-directional communication and control system which includes a common network line over which messages are transmitted in a specific message format and a plurality of hardware based digital IC's which are coupled to said common network line and are arranged to receive messages from and transmit messages to said network line in said specific format. Specifically, the invention concerns a multipurpose two-way communication device which is connected to one of said digital ICs, said device being operable in a master mode in which said device interfaces an external controller to said network line through said connected digital IC so that said external controller can act as the master controller for said plurality of digital ICs coupled to said common network line.

Abstract: The coil of an electromagnetic contactor is controlled by a microcomputer which stores control data in an internal RAM memory. An integrated circuit chip provides a tightly regulated +5 volt supply voltage to the microcomputer and generates reset signals on power up and power loss. A logic circuit distinguishes a power loss reset from a power up reset and transfers the microcomputer to a STOP mode in which only the RAM is energized to retain the control data. Reserve power to energize the RAM during a power loss of up to several minutes in duration is provided by a large capacitor which is kept charged by the regulated +5 volt supply. Voltage on the capacitor is checked through the integrated circuit on power up to determine if sufficient voltage was maintained to assure the integrity of the RAM.

Abstract: A system for transmitting data via a telephone line by means of a data communications device (4) connected to the telephone line, at least one other communications device being connected to the telephone line and each device being switchable between an inactive state, in which the device is not in use and presents a high impedance to the telephone line, and an active state, in which the device reduces the telephone line voltage and signals can be transferred between the device and the telephone line, the system including a telephone line state detection unit (10) associated with the data communications device (4) and connected to the telephone line for electrically monitoring the telephone line to provide an indication of the state of another communications device connected to the telephone line.

Abstract: A bi-directional communication and control system includes a common network line over which messages are transmitted in a specific message format and a plurality of hardware based digital IC's which are coupled to the common network line and are arranged to receive messages from and transmit messages to the network line in the specific format is taught. Specifically, a multipurpose two-way communication device is taught which is connected to one of the digital ICs, the device being operable in a master mode in which the device interfaces an external controller to the network line through the connected digital IC so that the external controller can act as the master controller for the plurality of digital ICs coupled to the common network line.

Abstract: In a compressor system, surge detection is provided by sensing the current of the motor driving the compressor and reading oscillations of the current about the average thereof and above and below two opposite threshold levels from such average current and counting the polarity changes within a time interval containing so many samples of the current and defining a sliding window.

Abstract: An electronic watt-hour meter includes a multiplier/integrator circuit which performs "pulse height-pulse width" multiplication of current and voltage and simultaneously integrates the product of this multiplication to generate packets of electrical charge representative of the electrical energy consumed. A first set of switches alternately, at one-half the frequency of a pulse width modulated (PWM) signal having a duty cycle proportional to the current, connects one of a pair of capacitors to be charged by the voltage signal, and the other capacitor to dump charge into an accumulator. When charge in the accumulator reaches a preset value, a pulse is generated representing a predetermined unit of energy. When the first capacitor is connected to the voltage signal by the first set of switches, a second set of switches applies the voltage to the first capacitor in one sense when the PWM signal has one value and in the opposite sense when the PWM signal has a second value.

Abstract: An AC electric energy meter is coupled to a source of AC electrical energy and to an AC load. A sensing circuit senses the amount of AC electric energy consumed by the AC electric load. An AC electric energy measuring circuit generates a pulse signal representative of the amount of AC electric energy consumed by the AC electric load. A switching circuit receives the pulse signal from the AC electrical energy measuring circuit and controls current flow from the AC electrical energy source to a stepper motor to drive an output shaft of the stepper motor in a unidirectional manner based on the pulse signal. A register is coupled to the output shaft of the stepper motor for registering the amount of electrical energy consumed by the AC electric load based on the amount of rotation of the output shaft of the stepper motor.

Abstract: Apparatus for measuring current over a wide range generates an eight bit accurate, 16-bit dynamic range digital signal from a current transformer secondary. Two signals proportional to the rectified secondary current, one generated by a large burden resistor and the other by an amplifier with programmable gain and an overrange indication, are applied through a multiplexer to an eight bit analog to digital converter which has three selectable reference voltages. A microprocessor selects the input signal, converter reference voltage, and one of four levels of amplifier gain which provide the greatest resolution for the magnitude of the current being measured, and provides an appropriate scale factor, from 2.sup.0 to 2.sup.8, for the eight bit accurate digital signal generated by the analog to digital converter.

Abstract: In a microcomputer-based multi-function thyristor-controlled AC induction motor drive, the microcomputer effectuates the several control functions of the motor drive during respective time intervals corresponding to the sequence of firing of the thyristors, and upon each new time interval, depending upon the required delay angle, firing is effected as a function of a residual angle in terms of a multiple of said time intervals, and the firing sequence is shifted by an amount of time intervals in relation to the integer number of such time intervals within such delay angle. As a result, firing of the thyristor is performed by the microcomputer without impeding control function determination and with improved response to change in the delay angle.

Abstract: A master metering module is taught which utilizes a programmed microprocessor and externally operated switches to alert the module as to what kind of system is being monitored thereby. For example, is the system being monitored a .DELTA.-connected electrical system or a Y-connected electrical system. This is useful in providing output indications of line-to-line voltage or line-to-neutral voltage, for example. When measuring voltages whether line-to-line or line-to-neutral one voltage value is substituted from another. A differential amplifier is utilized to do this. In one case the differential amplifier subtracts one line voltage from another line voltage, but in another case it subtracts neutral or zero ground potential from a line voltage. A switching arrangement is provided which interconnects one terminal of the differential amplifier with the neutral input terminal and with a line input terminal through appropriate conditioning of the microprocessor.

Abstract: A ballast adaptor circuit which makes it possible to convert a conventional two lamp rapid start T12 ballast for operation of two T8 fluorescent lamps and by means of a simple modification that does not require cutting wires or extensive rewiring of the T12 ballast device. The adaptor circuit comprises an auxiliary circuit including a tuned series-parallel LC network connected in parallel with either one or both of the lamps. The LC network is tuned to supply an odd harmonic current to the lamps, preferably the seventh harmonic. Improved starting is achieved by adding a series RC circuit and a SIDAC trigger device to the network to produce voltage pulses at the peaks of the AC supply voltage.

Abstract: A ballast adaptor circuit which makes it possible to convert a conventional two lamp rapid start T12 ballast for operation of two T8 fluorescent lamps and by means of a simple modification that does not require cutting wires or extensive rewiring of the T12 ballast device. The adaptor circuit comprises an auxiliary circuit including a tuned series-parallel LC network connected in parallel with either one or both of the lamps. The LC network is tuned to supply an odd harmonic current to the lamps, preferably the seventh harmonic. Improved starting is achieved by adding a series RC circuit and a SIDAC trigger device to the network to produce voltage pulses at the peaks of the AC supply voltage.

Abstract: A bus differential relay which is capable of distinguishing between an internal bus fault and an external fault on a feeder line with saturation of the faulted feeder line current transformer during portions of the alternating current cycles thereof is disclosed. The relay generates a net current signal or differential signal from the signals generated by the feeder line current transformers of the protected bus section. During an internal fault, the current differential signal extends in amplitude beyond fault current limits and a trip signal is generated to interrupt current to the bus section. During an external fault with current transformer saturation, the current differential signal will include amplitude portions of the alternating current cycles which exceed the fault limits.

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: Ballast apparatus operates a HID lamp at high frequency and high power factor. Series-connected current-limiting input inductor and input capacitor connect across apparatus input and are tuned off resonance to pass predetermined lagging current. An additional input capacitor is connected across input terminals to that input power factor approaches unity. Full-wave diode bridge has input connected across series-connected input capacitor and filter capacitor connects across bridge rectifier output. During normal operation, the filter capacitor develops a DC potential which is current limited by series-connected inductor and capacitor. Inverter has input connected across filter capacitor and inverter an output that drives the HID lamp through a high-voltage generating and variable impedance resonant circuit.

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.