Abstract: A power supply device with a monitoring circuit for detecting an unbalance in a direct voltage transmitted between two line conductors and which is normally balanced with respect to ground potential. A voltage divider circuit is arranged between the two line conductors and consists of components which are identical in pairs. The center tap of the voltage divider is connected to ground potential and at further taps thereof in each case positive and negative part-voltages are produced. A first positive part voltage is compared with a second negative part voltage and a second positive part voltage is compared with a first negative part-voltage so that the balance of the direct voltage with respect to ground potential is simply and reliably monitored.

Abstract: A circuit arrangement for providing a store of energy for actuating an electrically operable device, incorporating a reservoir capacitor, comprising a transformer having low resistance windings, the primary winding of which is connectable to an alternating current high voltage supply in series with at least one resistance capacitor, and the secondary winding of which is connected to the reservoir capacitor through a rectifier, the capacitor being connectable to an electrically operable device, with the turns ratio of the transformer such as to produce a secondary current of sufficient magnitude to charge the reservoir capacitor in the time available for successive operations or successive operational sequences of the device.

Abstract: A voltage stability discriminating system for a power system is disclosed for calculating a multiple load flow solution relating to a voltage stability discrimination for a power system in which the voltage stability can be discriminated fast and accurately due to the fact that the voltage stability discrimination system of the power system is constructed such that the multiple load flow solution is estimated in advance during a calculation process of the load flow calculating means.

Abstract: An inverter-type fluorescent lamp ballast is powered from the power line by way of a common and either of two (or more) different power leads. When powering the ballast by way of the common and the first one of these two power leads, the power provided to the fluorescent lamp load is relatively high; when powering the ballast by way of the common and the second one of these two power leads, the power provided to the fluorescent lamp load is relatively low. The ballast itself is a self-oscillating half-bridge inverter loaded by way of a series-tuned high-Q LC circuit connected across its output. A pair of fluorescent lamps is series-connected across the tank-capacitor of the LC circuit. The inverter has two bipolar transistors, each driven by an associated saturable current transformer that provides for a transistor ON-time dependent upon the magnitude of an associated bias voltage.

Abstract: In a driving circuit for a stepping motor in which a phase current corresponding to a predetermined reference voltage is generated when an excitation signal for each phase of the stepping motor is being produced and a coil of the corresponding phase is excited by the phase current, the supply time of the phase current is controlled by the pulse signal of a pulse generator for varying the pulse width, thereby improving the rising state of the phase current.

Abstract: A load is provided, at all times when in operation, with a D.C. voltage having at least a minimum holding magnitude by: providing a source voltage having a peak magnitude greater than the holding magnitude; connecting the source voltage to the load only while the source voltage magnitude is greater than a preselected magnitude; charging from the peak source voltage magnitude an energy storage element while the load is connnected to the source voltage; energizing the load from the charged energy storage element whenever the source voltage magnitude is less than the preselected magnitude; increasing the effective impedance of the load whenever the load is energized by the storage element; and selecting the energy storage element to provide at least the holding voltage to the load during each time interval when the energy storage element is connected to the load.

Abstract: An electronic ballast circuit for fluorescent or other gaseous discharge lamps includes a resonant half-bridge inverter circuit. The source voltage to the inverter is a full-wave rectified line voltage together with a DC carry-over voltage for supplying power in the inter-cusp period of the recitified line voltage. A negative feedback circuit is responsive to lamp current to vary the inverter drive frequency and thereby regulate lamp current. The frequency response of the feedback loop is high enough and the gain-versus-frequency response of the inverter is such that lamp current and voltage are regulated to reduce the crest factor of lamp current to compensate for variation in the amplitude of the voltage across the semi-conductor switches.

Abstract: Subject invention relates to an inverter-type electronic fluorescent lamp ballast wherein a series-resonant LC circuit connected across the inverter's output is used for matching the inverter's operating characteristics to those of the fluorescent lamp. The fluorescent lamp, combined with a Varistor, is connected in parallel with the tank-capacitor of this LC circuit. Thus, the starting voltage provided for the lamp is limited by the voltage-clamping-effect of the Varistor; and before the fluorescent lamp starts, all the output current from the ballast flows through this Varistor. After the lamp has started, however, the ballast output current shifts away from the Varistor and over to the lamp--leaving only a negligible amount of current to flow through the Varistor on a continuous basis. The essential aspect of subject invention relates to using the current flowing through the Varistor--with the help of an isolating current transformer--for providing heating power to the lamp cathodes.

Abstract: A motor control circuit utilizes sample and hold circuitry whose operation is initiated by an analog switch to control the firing angle of silicon control rectifiers, thereby to minimize wasting of power supplied to the motor being controlled.

Abstract: A ringing signal supply, provided at a concentrator remote from a switching office, compares a fraction of its output with a low level reference ringing signal supplied from the switching office, and uses the comparison result to control a high voltage chopper which connects one of two d.c. supply voltages via a low pass filter to the output to produce the ringing signal at a desired frequency. A d.c.-d.c. forward converter produces the two d.c. supply voltages commonly for a plurality of ringing signal supplies whenever at least one of them is to produce a ringing signal.

Abstract: A ringing signal supply, provided at a concentrator remote from a switching office, compares a fraction of its output with a low level reference ringing signal supplied from the switching office to product an error signal. The error signal, if it exceeds a positive or negative threshold, is gated during respective half-cycles of a rectangular alternating voltage produced by an inverter to control a bidirectional switch to connect the inverter output to the input of a low pass filter, whose output constitutes the output ringing signal. In this manner the instantaneous voltage of the output ringing signal is modified to reduce the error signal, whereby the output ringing signal has the same frequency and waveform as the reference ringing signal. The inverter can produce the alternating voltage commonly for a plurality of ringing signal supplies.

Abstract: In an overcurrent protecting apparatus for interrupting overcurrent in accordance with a coordination tripping curve characteristic, there are provided a microcomputer, a current/voltage converter for converting an overcurrent into a first voltage, D/A converting means for converting each output successively delivered from the microcomputer into a second voltage, and comparator means for comparing the first voltage with the second voltage. The delivering of the outputs from the microcomputer to the D/A converting means continues until an output is delivered from the comparator means to a first input of the microcomputer. Another comparator is also provided for delivering its output to a second input of the microcomputer when the first voltage is extremely high.

Abstract: A capacitor is charged to high voltages from a low voltage source of low energy capacity in a more efficient manner by charging the turn ratio of a transformer coupled between the inverter and rectifier in arbitrarily related slope as the voltage reaches predetermined levels.

Abstract: An ozone generating apparatus is disclosed which comprises a power source device for feeding a rectangular waveform alternating current between the discharge electrodes of a discharge tube of an ozone generator. One or both of the output current and frequency of the power source device is controlled to overcome the disadvantages of the conventional ozone generating apparatus.

Abstract: A system for charging an energy storage capacitor for use with an electronic flash lamp or laser employs stepped sequential application of increasing charging voltages to the capacitor. In an inverter-type power supply, a transformer has a tapped primary and a single secondary, output of which is rectified and applied to the capacitor. A plurality of pairs of drive transistors are used to apply an alternating voltage to progressively decreasing portions of the transformer primary, in response to a feedback signal indicative of the voltage to which the capacitor has been charged. This feedback signal is utilized by a level detector and associated drive control logic to enable a different pair of drive transistors each time a preestablish charge voltage level has been reached. A driver inhibit circuit insures that, as each pair of drive transistors is alternating on and off, that one transistor is fully off before the other is turned on.

Abstract: An ozone generating apparatus is disclosed which comprises a power source device for feeding a rectangular waveform alternating current between the discharge electrodes of a discharge tube of an ozone generator. One or both of the output current and frequency of the power source device is controlled to overcome the disadvantages of the conventional ozone generating apparatus.