Abstract: A circuit breaker includes separable contacts, an operating mechanism opening and closing the contacts, a first processor determining an open or closed state of the contacts, and a wireless transceiver transmitting the open or closed state from the first processor and receiving a signal. A first accessory includes a wireless receiver, a second processor and outputs. A second accessory includes a wireless transmitter, a third processor and a circuit generating the signal for or communicating the signal to the third processor, which outputs the signal to the wireless transmitter, which transmits the signal to the wireless transceiver. The first processor receives the signal from the wireless transceiver and causes the mechanism to open or close the contacts. The wireless receiver receives the open or closed state from the wireless transceiver. The second processor receives the open or closed state from the wireless receiver and outputs the same to the outputs.

Abstract: A system displays information from and controls electrical switching apparatus, such as circuit breakers. The system includes a plurality of circuit breakers having separable contacts and a plurality of conditions, such as bus temperature and contact wear. A plurality of sensors are structured to sense the conditions of the circuit breakers and to communicate the sensed conditions over corresponding wireless signals. A display and control unit is operatively associated with the circuit breakers and is structured to receive the corresponding wireless signals and display information corresponding to the sensed conditions or to control the circuit breakers based upon one or more of the sensed conditions.

Abstract: A current transformer includes a CT core having a central opening, a height, a width, inner and outer radii, and a secondary winding disposed about the CT core. The CT core is formed from a winding of an elongated length of taped steel having a reluctance and a width. The CT core height corresponds to the taped steel width. The CT core width is equal to the difference between the outer and inner radii. An air gap having a reluctance, a width and a depth is disposed in the CT core. The depth is along a portion of the CT core height. The air gap width is substantially smaller than the CT core height and width. The air gap reluctance is substantially greater than the taped steel reluctance. The CT core has a permeability resulting from being annealed at a temperature of 1450 to 1550° F. for one hour.

Abstract: Maintenance trip functions override the normal or specified trip functions of a low voltage circuit breaker to reduce pickup currents and/or time delays to effect faster trips, which reduces arc energy produced by faults during maintenance or testing on a live circuit breaker.

Abstract: Protection is provided for servicing a distribution bus by grounding the line side of a circuit breaker through which the distribution bus is fed and then closing the circuit breaker. The trip unit of the circuit breaker includes logic, in addition to the normal protection logic, which opens the circuit breaker main contacts without delay if current is detected upon closing of the grounded circuit breaker. However, if the grounded circuit breaker has been closed for a selected period of time and then current is detected, the distribution bus is kept at zero potential by not operating the breaker. A breaker auxiliary switch with a mechanical delay provides the indication of the selected time interval after closing the circuit breaker.

Abstract: Protection is provided for servicing a distribution bus by grounding the line side of a circuit breaker through which the distribution bus is fed and then closing the circuit breaker. The trip unit of the circuit breaker includes logic, in addition to the normal protection logic, which opens the circuit breaker main contacts without delay if current is detected upon closing of the grounded circuit breaker. However, if the grounded circuit breaker has been closed for a selected period of time and then current is detected, the distribution bus is kept at zero potential by not operating the breaker. A breaker auxiliary switch with a mechanical delay provides the indication of the selected time interval after closing the circuit breaker.

Abstract: A microprocessor based overcurrent trip unit which generates trip signals as an adjustable function of current and time, has a visual representation of the trip function on a front panel with 2-color LEDs associated with the trip function serving as indicators of trip conditions when red, and of a selected programmable parameter when green. The green LEDs flash to indicate parameter selected for modification in a program mode and illuminate steady in a view mode.

Abstract: A circuit breaker includes separable contacts for movement between a closed position and an open position. An operating mechanism, which moves the separable contacts between the closed and open positions, has a closed state and an open or tripped state which corresponds to the open position. A current transformer senses electrical current flowing through the separable contacts as a sensed current. A trip mechanism employs the sensed current for tripping the operating mechanism to the tripped position to move the separable contacts to the open position. The trip mechanism includes a microprocessor which generates short delay and ground fault trip functions of electrical current and time. The microprocessor inputs a first interlock signal from a downstream electrical switching device which generates the first interlock signal with a first value when current through the downstream device exceeds a predetermined value and with a second value otherwise.

Abstract: A transfer switch system includes a controller which sends separately timed restart signals over a communications network to an addressable relay associated with each load in order to sequentially restart the loads following a transfer. When the loads are elevators, the controller sends a prepare to transfer signal to each elevator through the associated addressable relay directing the elevator to park at a floor with its doors open and delays making a discretionary transfer until all elevators send a reply message over the network that they are appropriately parked. A message from the utility directing a reduction in use of their power can be sent to the controller over the communications network through an additional remote station. The controller can then transfer to the alternate power source and/or send messages to selected loads to shut down.

Abstract: Transfer between alternative electrical power sources for highly inductive loads, such as motors, is made using an open transition with the load connected to the new source only after the voltage on the load bus has fallen below a predetermined value, preferably a value which is about 30% or less of the nominal source voltage.

Abstract: A microprocessor based overcurrent trip unit includes an analog circuit for monitoring phase currents in the electrical interrupting device. The analog circuit is adapted to interface with the microprocessor over a range of selectable setpoints for instantaneous tripping and at the same time accurately monitor the phase currents even during a condition when the current sensing transformers are saturated. The overcurrent trip unit also allows the function of the long time delay characteristics of protection curve to be varied in order to provide better coordination with the characteristics of other overcurrent tripping devices in an electrical distribution system, such as a current limiting fuse, thereby enhancing the overall reliability of the system. For example, the function may be varied to provide either a fixed or FLAT, It, I.sup.2 t and I.sup.4 t functions.

Abstract: In a computer-based motor drive, a microcomputer is responsive to a plurality of input signals drived from the motor AC lines whenever contacts, or pushbuttons, commanding specific control operations to be performed, are closed. In such case, opto-couplers convert such AC voltage into a square pulse train which conveys a succession of digital high and low levels. A reference signal is derived, through an opto-coupler form the AC line, which in its high and low logic form is delayed in relation to the input signal trains. By sampling the input signal upon the occurrence fo a falling edge of the reference signal, then at least after the delay existing between the signals, the validity of the input signal is tested by comparing the two successive samples, thereby insuring a true command addressed to the microcomputer.

Abstract: An automatic transfer switch with microprocessor and a display which includes clusters or combinations of display cells. There may, for example, be sixteen display cells for a 16-word display. The display cells are driven by two serially connected shift registers, the input of the first of which is interconnected with the microprocessor. Sixteen digital words are supplied in sequence to the shift registers. One portion of the digital word is then provided in parallel to each of the display cells simultaneously but another portion of the word is supplied to an encoding device which tells which of the sixteen display cells will display that word. One 16 word message requires sixteen reiterations performed at high speed so that it appears that all sixteen display devices are actuated simultaneously to display one multi-word message.

Abstract: A feedback controlled elevator door control system 30 having motoring and generating modes, including a DC motor 35 connected to a DC power supply 36 via a power bridge circuit 68. Protective features include a dynamic current limit reference 200 having a magnitude which changes with motor speed; control 116 for providing an object detection safety-stop speed pattern having parameters which are selectable independent of the door stopping portions of normal opening and closing speed patterns; a bridge monitor 66 which prevents the changing of door commands when motor reversal could cause a bridge short; a power supply monitor 40 which blocks door commands when the control voltage is below standard; and an over-voltage protection monitor 38 which protects against excessive voltage build-up on DC power supply components when the bridge circuit 68 pumps power back to the DC power supply 36 during a generating mode.

Abstract: An automatic transfer switch is taught which includes as part thereof a voltage sensing device which is interconnected with one of the lines to be monitored and controlled by the automatic transfer switch and neutral. This voltage may vary over a wide range and it is desired to provide a universal transfer switch control for operation over the wide range. The output analog voltage is provided to an analog-to-digital converter which has a maximum number of output bits. In order to keep the resolution of the output digital signal from the analog converter as high as possible, it is necessary to range the input voltage according to a menu of potential ranging values which are stored in the memory of a microprocessor. A programming device is utilized to input the line voltage and the microprocessor determines the maximum value for the ranging constant as a function thereof. The output analog voltage is reduced by this factor then provided to the analog-to-digital converter.

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: 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 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.