Abstract: A dual-rated current transformer circuit has a first circuit which delivers a first current and a second circuit which delivers a second current. A current transformer is coupled to both the first and second circuits, wherein the transformer generates a current proportional to the current of each of the first and second currents.

Abstract: A circuit for generating at least two output voltages in response to an input current. A first stage comprises a first impedance for providing a first output voltage when the input current passes through the first impedance. At least a second stage comprises a second impedance coupled to the first impedance, wherein the second impedance provides a second stage voltage when the input current passes through the second impedance. At least a second output voltage is equal to the sum of the second stage voltage and the first output voltage. The second stage further comprises a second stage shunt operable to shunt the input current away from the second impedance when the magnitude of the second output voltage is above a predetermined amount.

Abstract: An apparatus for tripping a circuit breaker having a trip coil. A trip circuit is coupled at a first node to a first power supply and at a second node to the trip coil. The trip circuit comprises a switch for closing in response to a control signal, a coil coupled to the switch so that current is allowed to flow through the coil when the switch closes, relay contacts operatively coupled to the coil so that the relay contacts close when current flows through the coil, and a zener diode for providing a low impedance path after the relay contacts close and for applying a holding voltage across the coil sufficient to keep the relay contacts closed while current flows through the low impedance path.

Abstract: A circuit for generating at least two output voltages in response to an input current. A first stage comprises a first impedance for providing a first output voltage when the input current passes through the first impedance. At least a second stage comprises a second impedance coupled to the first impedance, wherein the second impedance provides a second stage voltage when the input current passes through the second impedance. At least a second output voltage is equal to the sum of the second stage voltage and the first output voltage. The second stage further comprises a second stage shunt operable to shunt the input current away from the second impedance when the magnitude of the second output voltage is above a predetermined amount.

Abstract: A series flyback switching regulator, having a transformer with a primary coil for receiving an unregulated input voltage and a secondary coil for providing a regulated output voltage, includes a circuit for limiting the magnitude of a substantial overload or short circuit current. The current limiting circuit senses the magnitude of current flowing through the primary coil and sets a current limit level which is based upon a predetermined maximum current allowed in the primary coil. The current limiting circuit also senses the magnitude of the voltage present at the secondary coil of the transformer and reduces the current limit level, based upon a sensed reduction in the secondary coil voltage. The input voltage is removed from the primary coil when the magnitude of the current through the primary coil exceeds the current limit level as reduced by the sensed reduction of the voltage appearing across the secondary coil.

Abstract: A relay spare circuit for a recloser relay provides an output signal selected to occur during a particular segment of the reclose cycle of a fault-responsive circuit breaker. A set of switches is provided to select which of a plurality of available recloses are to be used and where in the resulting reclose cycle the relay spare is to operate, and a logic circuit is provided which compares the selected switches with a counter responsive to advancement of the recloser relay through the reclose cycle, to provide the relay spare output signal at the selected point in the reclose cycle.

Abstract: A timing controller which supervises the reclosure of a fault responsive circuit breaker which includes a plurality of selectable switches for developing signals representing the reset and reclose delay times for the recloser relay operatively associated with the fault responsive circuit breaker; a plurality of multiplexers for receiving the signals developed by the selectable switches and for developing serially formatted digital words in accordance with such signals for delivery to an output controlling multiplexer; a first counter assembly for regulating the output of the output controlling multiplexer in accordance with the condition of the recloser relay; a storage device for receiving and storing the output of the output controlling multiplexer; and a comparison device for comparing the stored output of the output controlling multiplexer with a second counter assembly which develops a timed output signal.

Abstract: A circuit is disclosed which performs two functions: (1) it develops a D.C. voltage signal which is proportional to the difference between the D.C. voltage components of a first and a second voltage, each comprising a D.C. voltage component and an A.C. voltage component impressed thereon, and (2) it filters the A.C. voltage components of both the first and second voltages. This circuit comprises cascade-connected first and second networks, each comprising an operational amplifier, with the output of the first network coupled to the input of the second network. Said first voltage is supplied as an input to the first network, and said second voltage is supplied as an input to the second network. The second network develops a D.C. output signal that is representative of the difference between the D.C. voltage components of the first and second voltages.

Abstract: A drive circuit responsive to an applied electrical signal for generating a voltage to control the actuation of an electromagnetic relay is disclosed. The voltage has a first and a second level for picking-up and holding-in, respectively, the relay. The first voltage level has a peak value which is developed by an internal charging circuit and is additive to the second voltage level supplied by an external source. The first voltage level is higher than required to actuate the relay which enhances the pick-up speed of the relay.

Abstract: A D.C. to D.C. voltage converter is disclosed that operates with various applied D.C. input voltages, each having a different voltage level, to develop a desired D.C. output voltage. The D.C. to D.C. voltage converter has a saturable transformer that is sequentially excited into its positive and negative saturation conditions under control of sequentially operating first and second transistor diode combinations. The D.C. to D.C. converter has a base drive current circuit comprised of a full-wave rectifier and a multiple level current limiting circuit. The base drive current circuit is interposed between a base drive winding of the saturable transformer and the base electrodes of the transistors of first and second transistor diode combinations. The base drive circuit adapts the saturation condition of the first and second transistor diode combinations to the level of the applied D.C.

Abstract: Apparatus is described for the generation of a series of binary numbers which has a minimum value other than zero, has a major sequence of numbers in which successive numbers are separated by a first fixed increment starting from the minimum value and defining the range of the series of numbers, and has a plurality of minor sequences, each representing binary numbers of the series lying between respective successive numbers of the major sequence with each number of a minor sequence being spaced from a preceding number thereof by a second fixed increment.

Abstract: Digital overcurrent relay apparatus utilizing sampling, digital conversion and digital comparison techniques is described. The apparatus provides a trip signal after an alternating current in a line being monitored by the apparatus exceeds a preset pick up value for a period of time which is an inverse function of the magnitude of the current expressed in multiples of pick up value.

Abstract: Digital overcurrent relay apparatus utilizing sampling, digital conversion and digital comparison techniques is described. The apparatus provides a trip signal after an alternating current in a line being monitored by the apparatus exceeds a preset pick up value for a period of time which is an inverse function of the magnitude of the current expressed in multiples of pick up value.

Abstract: An analog-to-digital converter is described in which a sequence of samples of an analog signal is converted into a sequence of binary numbers which appear at the output terminals of a composite counter comprising a first counter and a second counter. The first and second counters are gated in sequence by gating waveforms to provide for each sample the count corresponding to the logarithm of the sample. The gating waveforms are derived from a charge and discharge cycle of a capacitor to which the sample is supplied. Selected times in the charging and discharging portions of the cycle are utilized for deriving the gating waveforms.

Abstract: A static trip unit for automatic electric circuit breakers includes an analog to digital converter for converting an analog signal proportional to the magnitude of current flowing in a distribution circuit to a digital signal having a pulse frequency proportional to the second power of the analog signal. When the analog signal exceeds a preselected threshold level, a binary counter is conditioned to accumulate the digital signal pulse. A decoder monitors the pulse count accumulating in the counter and issues a trip signal when the pulse count reaches a preselected total.

Abstract: A multi-function solid state trip unit for automatic electric circuit breakers incorporates indicators functioning to signal which of the functions, e.g., short circuit, overload or ground fault, was operative in tripping the circuit breaker. A bypass circuit is included to insure that tripping of the circuit breaker is not jeopardized by failure of the indicators.

Abstract: A control circuit for reversibly driving a motor from a small d-c voltage. A switched a-c voltage source is selectively applied to the primary windings of either of two voltage step down transformers. The a-c voltage of each secondary winding is rectified and applied to the motor through a series resistor. The rectified voltage from one transformer drives the motor in one direction and the rectified voltage from the other transformer drives the motor in the reverse direction.