Abstract: A power converter for converting shore power voltage, phase, and frequency for shipboard use includes a variable inductance input transformer that can be connected to the shore power. The primary windings of the transformer have a plurality of taps, and a respective computer-controlled switch is connected between adjacent taps to selectively establish a closed circuit or an open circuit between the taps and thereby configure the primary windings as a low or high voltage "delta" or "wye", as appropriate for the shore power voltage. The output of the input transformer is sent to a variable speed drive, then to an output transformer, and thence to the distribution bus of the ship. A voltage regulator regulates the output voltage of the output transformer. If desired, a phase selector can be provided between the shore power and input transformer to establish the phase characteristics (i.e.

Abstract: An internal AC adapter which incorporates a space efficient EMI filter is positioned within a main chassis portion of a portable personal computer having at least one energy-demanding component also positioned within the main chassis portion. The internal AC adapter, which converts alternating current received from an alternating current main to direct current for transmission to the energy-demanding components, includes a first connector for electrically connecting the internal AC adapter to the alternating current main, a bridge rectifier circuit having an AC input side electrically connected to the first connector and a DC output side and a space efficient electromagnetic interference filter having an input side electrically connected to the DC output side of the bridge rectifier circuit and an output side. The bridge rectifier circuit converts alternating current received from the first connector to direct current for transmission to the electromagnetic interference filter.

Abstract: The double modulation converter (DMC) is a DC-AC converter for driving an AC-DC converter. It has two input terminals for connection to a DC voltage source, two output terminals for connection to an AC-DC converter, and a plurality of circuit control terminals for receiving a plurality of control waveforms which cause a bipolar stream of width- and amplitude-modulated pulses to appear at the output terminals when a load is connected across the output terminals. The basic elements of the DMC are two switches connected in series across the input terminals. One output line connects an output terminal to the junction of the two switches. The other output line connects the other output terminal to one of the input terminals. During operation, the two switches periodically and alternately open and close, the closure of one switch causing a pulse of one polarity to appear across the output terminals, and the closure of the other switch causing a pulse of opposite polarity to appear across the output terminals.

Abstract: A ballast filter in which the ballast can operate at a total harmonic distortion of power line current of less than 10%. Power dissipated by the filter when at a THD of less than 10% is relatively low. The input impedance of the ballast is chosen to be no greater than twice the equivalent filter impedance of a front end filter and no less than the equivalent filter impedance/1.5. The filter includes a transformer having a core which at times operates within the non-linear region of its B-H curve under nominally rated ballast load conditions.

Abstract: A saturating inductor or transformer is used to shape input current flowing into an alternating current (AC) to direct current (DC) power supply to correct the power factor for the supply. If a saturable inductor is used, it is connected to feed current into the power supply and a capacitor is connected across the input of the power supply. The capacitor precharges the saturable inductor to a point just short of saturation during a preliminary portion of each sinusoidal half cycle of the input AC power. For steady state operation, this is the point at which current will start to flow into the AC to DC power supply and the inductor will saturate. Since the inductance falls in accordance with a permeance curve characteristic of material used to construct the inductor, the current will continue to flow at the same or an increasing level despite the declining voltage level of the AC input power.

Abstract: A godet for heating an advancing yarn including a rotatably mounted godet casing of magnetically conductive material, a stationary primary winding, and a power supply for powering the primary winding at least about 300 Hz. The godet casing is formed of iron and acts as both the secondary winding and core for the primary winding. Accordingly, the godet casing does not need a separate and defined secondary winding, nor does the godet casing include a copper insert or copper coating on the interior of the casing.

Abstract: A DC-DC converter utilizes a tapped transformer secondary winding as a means of achieving output voltage ripple cancellation. This ripple cancellation occurs at a specified input voltage. It operates by fixing the location of a tap on the secondary winding of the power transformer so that the output voltage ripple cancellation occurs at the specified input voltage. It also minimizes the volt seconds that must be sustained by the output filter inductor over a specified range of input voltage for the converter.

Abstract: A circuit for correcting power factor and for reducing ac line current harmonic components in conjunction with bridge-connected capacitive-filtered loads and for providing a source of ac startup current for associated circuitry, for example a switch mode power supply which may form part of the load. The circuit comprises a rectifier bridge, a dual-tuned circuit having a tuned filter in series between an ac line input and the bridge, and a shunt capacitor across the input to the bridge. The tuned filter comprises a parallel connected inductor and capacitor, the shunt capacitor being tuned with the inductor to form a trap filter to reduce third-order and higher harmonic components in the ac line current. The circuit also includes a current source operatively connected to the shunt capacitor for providing a source of ac current immediately upon application of ac power to the ac line input.

Abstract: In a DC-DC converter, the primary circuit has a bridged switching circuit which applies an input CD voltage to the primary winding of a transformer in response to turn-on pulses to generate alternating current pulses through the primary winding and an anti-biasing capacitor. First and second diodes are coupled respectively to opposite ends of the secondary of the transformer to allow energy stored therein to be discharged into a smoothing capacitor through a first smoothing inductor. Third and fourth diodes are coupled respectively to the opposite ends of the secondary winding to allow energy subsequently stored therein to be discharged into the smoothing capacitor through a second smoothing inductor.

Abstract: The switching power supply has high output power and high efficiency. The input voltage may be AC or DC. The input current may be constant or sinusoidal, output voltage fixed or variable. Smallest possible peak currents of switches result in best possible line and component utilizations at any time. In particular, inrush and surge currents are eliminated. A diode applies the input voltage to the output. A capacitor is coupled to the input for storing a base voltage. A switch selectively couples the capacitor to the output. A converter is used to convert the output voltage into the base voltage. The load is coupled to the output and further to the input or ground. A filter can be used to reduce output ripple voltage.

Abstract: An arrangement includes a network for connection between an AC power supply and the input of a DC power supply containing rectifiers and a filter capacitor. The network forms a third order, damped low-pass filter that waveshapes the AC input current so as to either reduce or remove the magnitude of harmonics which primarily cause distortion of the input current waveform. In a preferred embodiment, the waveshaping network includes an inductor connected in series with the input of the DC power supply. A series combination of a damping resistor and a first capacitor is connected in parallel with the series inductor. A second capacitor is connected in shunt with the input terminals of the DC power supply. The waveshaping network increases the power factor and lowers the total harmonic distortion the input of the DC power supply presents to the AC power supply.

Abstract: A circuit for reducing the commutation transient in a switch-driven (12) free-wheeling rectifier (20) applied to a load (10) via a continuously conducting energy conducting inductor (28), in which a further inductor (34) and diodes (32, 38) are interconnected with the switch-driven rectifier (20) to free-wheel recovered commutation energy from rectifier (20) when the switch is non-conducting. In other circuit variations temporary energy storage is aided by one or more capacitors (72) and additional diodes (52, 54, 80, 107, 122) during turn-on of rectifier (20), which energy recycled back into the circuit to minimize power dissipation and reduce circuit component heating.

Abstract: An arrangement includes a network for connection between an AC power supply and the input of a DC power supply containing rectifiers and a filter capacitor. The network forms a fourth order, damped lowpass filter that waveshapes the AC input current so as to either reduce or remove the magnitude of harmonics which primarily cause distortion of the input current waveform. In one embodiment, the waveshaping network includes a tapped inductor connected in series with the input of the DC power supply. A series combination of a damping resistor and a first capacitor is connected in parallel with the series inductor. One end of a second capacitor is connected to the tap of the inductor. The waveshaping network increases the power factor and lowers the total harmonic distortion the input of the DC power supply presents to the AC power supply.

Abstract: High efficiency, post regulation of auxiliary outputs in multiple output-power supplied is provided by connecting a regulating switching device in parallel with a filter inductor connected in the current path from the rectifiers to the output terminal. For minimum output power for that auxiliary output, the switching device is held off at all times. When increased power is required, the switching device is turned on for a short period during each cycle of the inductor voltage. The switching system may be configured to conduct current from the output end of the inductor to the input end of the inductor or vice versa or either one selectively, in accordance with the particular regulation scheme chosen. Efficiency is maximized since current flows in the switching device for only a small portion of each cycle of the inductor voltage.

Abstract: High efficiency, post regulation of auxiliary outputs in multiple output-power supplies is provided by connecting a regulating switching device in parallel with a filter inductor connected in the current path from the rectifiers to the output terminal. For minimum output power for that auxiliary output, the switching device is held off at all times. When increased power is required, the switching device is turned on for a short period during each cycle of the inductor voltage. The switching system may be configured to conduct current from the output end of the inductor to the input end of the inductor or vice versa or either one selectively, in accordance with the particular regulation scheme chosen. Efficiency is maximized since current flows in the switching device for only a small portion of the cycle of the inductor voltage.

Abstract: Method and apparatus for performing AC/DC conversion to provide a regulated DC output with reduced distortion of the AC supply waveform. An AC supply is filtered and rectified to provide a DC signal. A plurality of flyback circuits, each having a series connection of a switch and a first winding which is connected in parallel to the rectifier circuit, as well as a second winding which is inductively related to the first winding, are provided. The second winding from each flyback circuit is connected in parallel through ORing diodes to form an output. The switches in each flyback circuit are repeatedly enabled and disabled in sequence. The first winding in each flyback circuit is energized from the DC signal when the respective series switch is enabled. When the switch is disabled, the inductively related second winding is energized. The combined output from each of the second windings provides a regulated DC signal.

Abstract: An inverter apparatus having a reactor which suppresses ripple components contained in a charging current for a battery and is saturated when a current having a value larger than a predetermined value flows therethrough to have a very small inductance and allowing a small size and a low cost thereof to be designed.

Abstract: A rectifier circuit having a rectifier (D4) allowing current to flow in a forward direction to an output (V.sub.OUT). A saturable inductor (L3) in series with the rectifier (D4) blocks reverse recovery rectifier current and directs it to an inductor (L4), the energy stored in that inductor re-setting the saturable inductor (L3) to allow subsequent flow of current in the forward direction to the rectifier (D4). A capacitor (C2) absorbs surplus energy from the inductor (L4) and a rectifier (D5) guides that surplus energy to the output (V.sub.OUT). This rectifier circuit is particularly useful as part of a convertor where an electronic switch repeatedly switches current through an inductor (L1) and the energy from the inductor (L1) is delivered to the output (V.sub.OUT) via the rectifier circuit.

Abstract: An AC/DC converter is provided, suitable for use in an advanced single phase, sine wave voltage, high frequency power distribution system, such as that used on a 20 kHz Space Station Primary Electrical Power Distribution System. The converter comprises a transformer, a resonant network, a current controler, a diode rectifier and an output filter. The voltage source is converted into a sinusoidal current source. The output of this current source is rectified by the diode rectifier and is controlled by the current controller. The controlled rectified current is then filtered by the output filter to obtain a constant voltage across the load.

Abstract: The power factor correction circuit can deliver a high output power, high efficiency and high power factor. AC, e.g. line, voltage is converted into DC voltage. The high power and high efficiency are achieved by using diodes as only semiconductor devices conducting higher average currents. The correction circuit has an input and output. A rectifier network is coupled to the input for providing a pair of rectified signals. One rectified signal is applied to the output. A capacitor stores a DC voltage. A charging circuit selectively applies the other rectified signal to the capacitor. A diode applies the DC voltage to the output. A sinusoidal input current can be obtained. Inrush and surge currents are eliminated.

Abstract: Instability resulting from the presence of reactive components in the output filter of regulated power supplies of the general type in which regulation is obtained by feeding back the output voltage to the regulator circuitry is eliminated by deriving a feedback signal from the output voltage which includes not only a direct component, but also separately derived first and second derivative components referenced to the reactive characteristics of a series output choke and parallel output capacitor of the output filter circuit. The amplitude ratios of the feedback signal components are selected in accordance with a key aspect of the invention to eliminate the output filter from the characteristic equation of the power supply to thereby eliminate instability whatever its source.

Abstract: Instability resulting from the presence of reactive components in the output filter of regulated power supplies of the general type in which regulation is obtained by feeding back the output voltage to the regulator circuitry is eliminated by deriving a feedback signal from the output voltage which includes not only a direct component, but also separately derived first and second derivative components referenced to the reactive characteristics of a series output choke and parallel output capacitor of the output filter circuit. The amplitude ratios of the feedback signal components and the elements of the local feedback loop of the regulator error amplifier are selected in accordance with key aspects of the invention to eliminate the output filter (including the effective series resistance of the output filter capacitor) from the characteristic equation of the power supply to thereby eliminate instability whatever its source.

Abstract: A system for converting variable frequency multiple phase current into multiple phase current of constant frequency with a neutral having a multiple phase inverter with a neutral (N) is disclosed. A first input (34) is connected to the multiple phase inverter for receiving pulses of a positive polarity. A second input (36) is connected to the multiple phase inverter for receiving pulses of a negative polarity. A variable frequency multiple phase source (12, 14 and 16) of alternating current applies current to a multiple phase transformer (80, 142 and 180). Current from the transformer is applied to a full-wave rectifier (96) which has a first group of diodes (112) which applies the positive pulses to the input (34). A second group of diodes (116) applies the negative pulses to the input (36). The ripple frequency f.sub.

Abstract: An arrangement for improving the power factor at the input of an off-line switching type power supply is operative to extend the duration of the pulse current conducted by the diode rectifiers. A parallel LC ringing circuit is introduced between the AC line and the rectifier of the switching type power supply to enhance the voltage enabling conduction of the rectifying diodes and hence initiate current flow through the rectifying diodes earlier in each half cycle. This extends the conduction interval of the rectifying diodes significantly and enhances the power factor at the input to the switching type power supply.

Abstract: A DC to DC converter is described having a bridge circuit coupled to the secondary windings of a transformer, the transformer supplying power to a capacitor and a constant current load source. The circuit parameters are chosen to provide a circuit that has quasi-resonant characteristics close to the frequency of the signal providing power to the transformer, but at a higher value. Other constraints on the circuit parameters are discussed. The resulting circuit provides an efficient transfer of energy from the source power supply to the load.

Abstract: A power factor compensator (18) for a power converter (17) comprises an L-C circuit connected in series between the power converter and the converter's A.C. power source (13). The values of the inductor (30) and the capacitor (31) of the compensator circuit are selected to cause the L-C circuit to resonate at a frequency higher than the power source frequency, preferably at a frequency ranging between 1.4 and 3.5 times the power source frequency, in order to achieve a power factor within the range of about 0.65 to 0.95. A resonant frequency of about twice the power source frequency has been experimentally found to give particularly good performance.

Abstract: A device for reducing the leakage noise of a power converter having a rectifier circuit connected to an alternating current power source and an inverter circuit connected to the rectifier circuit has a first noise filter, with a plurality of inductors and capacitors, and which is coupled between the alternating current power source and the rectifier circuit; and a second noise filter, with a plurality of inductors and capacitors, and which is coupled between the rectifier circuit and the inverter circuit.

Abstract: A circuit and method using a low frequency active switch for improving input power factor in power supplies utilizing a full wave rectifier and capacitor filter for supplying a filtered DC voltage from an AC power source. A switch control activates and deactivates an active switching once in each half cycle of the alternating voltage input. The switch control is connected to the active switching for operating the circuit providing high power factor.

Abstract: A high frequency DC to DC converter having at least two phase differentiated pulsed voltage sources, utilizes two phase differentiated unidirectional power flow resonant circuits to permit multiple quasi resonant operation of the converter and thereby gain the benefit of lowered EMI, high efficiency, lowered component stress and increased power throughput.

Abstract: To reduce network harmonics upon connecting a fluorescent lamp (LP1) with a power network rectifier (2) and a push-pull frequency generator (3) and a series resonance circuit (4) to the network, a harmonic filter is connected in the circuit with the fluorescent lamp (LP1) or lamps (LP1, LP2). The harmonic filter includes two diodes (D8, D9), connected in forward current passing direction to the power rectifier (2), and two capacitors (C7, C8) connected, respectively, between the serially connected diodes and a center tap (M1) between the push-pull transistors directly and beyond an inductance forming part of a series resonance circuit (4) for the lamps. In parallel to the two diodes, two further diodes (D10, D11) are provided, having a center tap (M4) which is connected over a capacitor (C9) also to the center tap between the transistors of the push-pull frequency generator (3). Preferably, the capacity value of the further capacitor (C9) is about 0.

Abstract: A d.c. to d.c. converter system converts a d.c. signal into a pulsating a.c. signal, which is applied to the primary of a power transformer. A transformer in which the primary and secondary windings are planar is employed to generate the output pulse signal. The planar transformer design provides the inductance required to filter the output signal and reduce the ripple therein, while simultaneously providing tight coupling between the primary and secondary windings. A single turn secondary winding is provided to reduce the number of turns in the transformer and thereby reduce the associated power loss.

Abstract: A circuit arrangement having a purely capacitive power supply, at least one power consumer, and a control element for causing power to be supplied to the power consumer. The power supply, the power consumer and the control element form a series circuit. The power consumer has a relay activated by a switching transistor, the switching transistor is connected to the control element. The purely capacitive power supply has a series capacitor for defining the current flow in the series circuit. The circuit arrangement may have a plurality of power consumers connected in series with each other and in series with the power supply and the control element.

Abstract: A high frequency power converter circuit having a transformer comprised of a magnetic element having a through hole in combination with a pair of diodes having opposed terminals and at least one of which extends through the magnetic circuit element through hole. Bussbar conductors have the diodes and magnetic element coupled therebetween. The circuit inductance is formed by a further magnetic circuit member associated with one of the bus conductors.

Abstract: Disclosed is an electrical power system adapted to receiving power from a source of alternating current, typically a small alternator, and supplying a direct current potential to a load. This power system includes two stages, the first stage comprising switchable rectifying devices such as silicon controlled rectifiers which interact with the impedance of the alternator or other source of alternating current power as a switching regulator to create an intermediate direct current potential. The second stage operates from this intermediate direct current potential to produce a slightly lower output voltage, and creates a more accurate regulation than is possible with the first stage alone, the second stage greatly reduces ripple and high frequency noise components contained on the output of the first regulator stage. The second stage serves as an active low pass filter tuned to a desired DC voltage.

Abstract: A filter circuit is provided in the secondary of a power transformer following a rectifier and is composed of two chokes respectively arranged in the series arms of the lines leading to two output terminals, and at least one shunt capacitor. Each of the chokes is composed of a winding fashioned as a strip-shaped interconnect, whereby both windings are conducted through a common magnetic core in the same winding sense.

Abstract: A resonant forward converter at a switching frequency of 10 MHz provides a small volume point-of-load converter for distributed power systems. The leakage inductance of a transformer is made negligibly small relative to the magnetizing inductance of the transformer. This enables a resonant controllable switch on the primary side of a transformer and a secondary side rectified diode to be switched either on or off at the same time. The capacitance across the primary side switch and the secondary side diode rings with a resonant inductor connected in parallel with the transformer. Both the switch and diode, therefore, have zero voltage switching transitions. Further, the resonant inductor being connected in parallel with the transformer provides a resonant ring that is independent of load.

Abstract: An AC/DC converter comprises a half-bridge electronic self-oscillating inverter powered from the non-filtered full-wave-rectified 120 Volt/60 Hz power line voltage, and its resulting amplitude-modulted 30 kHz output voltage is applied to a series-resonant L-C circuit. The 30 kHz voltage developing across the tank capacitor of this L-C circuit is rectified and applied as DC to an energy-storing capacitor, from which the AC/DC converter's output is supplied. Trigger pulses are provided to trigger the inverter into self-oscillation at the beginning of each pulse of DC voltage provided by the unfiltered rectified power line voltage. As soon as the magnitude of the DC voltage across the energy-storing capacitor exceeds a first level, the trigger pulses cease to be provided. As soon as the magnitude of the DC voltage on the energy-storing capacitor falls below a second level, the trigger pulses are again provided.

Abstract: The reduction of non-monotonic degradation characteristics induced in the output signals in high-power applications of a transformer which has a primary winding and n secondary windings which have a total of N turns, where n and N are integers, is accomplished by replacing the n secondary windings with m replacement windings, where m is an integer less than n. When the replacement windings have a total of N turns, they produce an output signal with reduced degradation normally caused by stray capacitance and inductance leakage in the secondary windings.

Abstract: A resonant converter feeds five load circuits while maintaining excellent voltage regulation. The power converter features a non-bifilar wound transformer with the resonant capacitors serving the dual function of suppressing diode voltage switching transients while forming the resonant circuit in conjunction with the transformer. Overcurrent circuit protection is also provided.

Abstract: In an AC/DC converter, the dissipation voltage sharing resistors commonly placed in parallel with the series capacitors are replaced by a resistor balancing path derived from the capacitor junction point to a symmetrically disposed voltage reference point belonging to the AC input vectorial system.

Abstract: A self-oscillating power converter utilizes a MOSFET power transistor switch with its output electrode coupled to a tuned network that operatively limits the voltage waveform across the power switch to periodic unipolar pulses. The transistor switch may be operated at a high radio frequency so that its drain to gate interelectrode capacitance is sufficient to comprise the sole oscillatory sustaining feedback path of the converter. A reactive network which is inductive at the operating frequency couples the gate to source electrodes of the transistor switch and includes a variable capacitance as a means of adjusting the overall reactance, and hence the converter's switching frequency in order to provide voltage regulation. A resonant rectifier includes a tuned circuit to shape the voltage waveform across the rectifying diodes as a time inverse of the power switch waveform.

Abstract: A circuit arrangement for large power transformers with a low-voltage winding, a main high-voltage winding and a step winding as well as a step switching device at a Y-point side thereof, includes, at a location between a point connecting the step winding to the high-voltage main winding and the Y-point of the transformer, a capacitor in series with a resistor is connected electrically parallel to respectively current-carrying steps of the step winding, the capacitor and the resistor being of such dimensions as to decrease resonance amplitudes of the connecting point to ground, the capacitor being constructed of spirally wound strip lines formed of a resistance alloy, the strip lines being also of such dimensions as to reduce resonance amplitudes of the connecting points.

Abstract: An electronic ballast for energizing one or more gaseous-discharge lamps and for regulating the power consumed thereby, the ballast including a power supply for providing a source of DC power between a pair of outputs, a pair of transistors connected as switches in series between the power-supply outputs, the transistors for selectively coupling to the juncture thereof positive and negative potentials, a voltage-conditioning and current-limiting network for energizing the lamp from the potential developed between the transistor juncture and a power-supply common, and a pulse generator for developing pulses for driving each of the transistors in turn whereby a potential is developed at the transistor juncture which alternates as positive-going and negative-going pulses each separated by a dead time, the pulse generator for monitoring the power consumption level of the lamp and responsive thereto operative to vary the frequency and/or the width of the transistor driving pulses whereby the lamp consumption is re

Abstract: A regenerative d-c power supply comprises a bridge rectifier, a series-connected smoothing choke, a shunt-connected filter capacitor and a switching circuit consisting of a first diode disposed in a positive line of the d-c power supply between the smoothing choke and one terminal of the capacitor, a second diode disposed in a negative line of the power supply between another terminal of the capacitor and the rectifier and a pair of converter valves in the form of transistors connecting the cathodes of the diodes to one another and the anodes of the diodes to one another. Each converter valve is operated in the forward energy transmission direction by a respective first pulse sequence having pulses staggered in time with respect to the pulses of the other first pulse sequence. The converter valves are operated in the reverse energy transmission direction by respective second pulse sequences each having pulses staggered in time with respect to the pulses of the other second pulse sequence.

Abstract: A direct-current power supply circuit for gas discharge lamps includes a rectifier-capacitor bridge having a pair of input terminals and a pair of output terminals. A series input inductor is connected to one of the input terminals of the rectifier-capacitor bridge, and a pair of feedback diodes is connected to the output terminals of the rectifier bridge to provide a feedback signal to the series input inductor to control ripple of d-c output from said bridge and power factor of the a-c input to said bridge.

Abstract: A circuit for controlled power supply devices, particularly for autoconverters, for suppressing the oscillatory tendency in such device has an input filter forming a parallel oscillator circuit, which can be excited to oscillations on the basis of a partially negative input impedance of the autoconverter. A series oscillator circuit is connected to the parallel oscillating circuit and is tuned to the resonant frequency thereof, such that an impedance minimum occurs at the resonant frequency, whereas the parallel resonant maximums of the impedance, which appear at a lower and at a higher frequency, can be damped by a comparatively small ohmic resistance, such that unwanted oscillations are prevented. The circuit represents a low capacitive load to the feed network, and exhibits low dissipated power through the ohmic resistor, making the circuit particularly adapted for high output power packs which are operated by a three-phase network.

Abstract: The voltage present at an input is chopped by a switch which is actuated by a pulse-width modulator controlled by the output voltage and is smoothed at least by a low-pass filter, consisting of an inductance and a capacitance, at the output. In order to reduce to a minimum the delay between the time an input voltage is applied and the time a rated value is at least approximately reached by the output voltage, the inductance is bypassed by a bypassing circuit which has a low inductance and which conducts if the output voltage is below a minimum voltage and in other cases is turned off. It contains, for example, a switch which is constructed as a switchable current source and which is actuated by a comparator comparing the output voltage with a reference voltage. In transformer-coupled embodiments, isolation between the output and the input is possible. The supply unit is suited, for example for supplying auxiliary devices of an instrument transformer from the current of the power-line to be monitored.

Abstract: A flyback type DC/DC converter includes an input filter with input capacitor (C.sub.1), an inductance (L) in series with a power transistor (T) and an output filter with an output capacitor (C.sub.2). The input capacitor (C.sub.1) is connected in series with the output capacitor (C.sub.2) and to the input terminals of the converter to compensate the ripple current in the output capacitor (C.sub.2).

Abstract: Surge protection is provided for a d-c power supply, wherein rectified a-c line voltage is filtered in an LC filter having a shunt-connected filter capacitor, by inserting a limiting resistor in series with the filter capacitor during power-up to reduce the inrush current and the voltage overshoot to acceptable values. Once the power-up period is over and d-c power is fed to a load, the limiting resistor is bypassed.

Abstract: When a series string of similar circuit components, such as capacitors, are connected across a source of d-c voltage and those circuit components do not divide the applied voltage equally because of having different leakage resistances, and consequently different leakage currents, the voltage imbalance may become so great that the maximum allowable voltage or voltage rating of at least one of the circuit components may be exceeded, resulting in damage to or the destruction of that component. To limit the voltage imbalance, thereby to protect the circuit components, each of those components is shunted by a separate voltage limiting device, such as a zener diode. The threshold or breakdown voltage of each limiting device is less than the maximum acceptable voltage of the device's companion circuit component so the voltage across that component will be limited to and will never be greater than that maximum acceptable level regardless of the differences that exist in the leakage resistances.