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Showing papers on "Three-phase published in 1978"


Patent
27 Nov 1978
TL;DR: In this paper, all harmonics of an order less than (6·N-1) are cancelled from the fundamental signal presented in each output phase of a three-phase converter as the sum of corresponding phase angle fundamental signals from an N number of converter bridges.
Abstract: All harmonics of an order less than (6·N-1) are cancelled from the fundamental signal presented in each output phase of a three-phase converter as the sum of corresponding phase angle fundamental signals from an N number of converter bridges, where N is a non-power of two

34 citations


Patent
10 Apr 1978
TL;DR: In this article, a three phase AC to DC voltage converter includes separate single-phase AC-to-DC converters for each phase of a three-phase source with the DC voltage output of the three converters paralleled and controlled to provide necessary regulation.
Abstract: A three phase AC to DC voltage converter includes separate single phase AC to DC converters for each phase of a three phase source with the DC voltage output of the three converters paralleled and controlled to provide necessary regulation Each of the single phase AC to DC converters includes a full-wave bridge rectifier feeding a substantially resistive load including an inverter and a second single phase full-wave bridge rectifier To the extent that each inverter and second single phase full-wave bridge rectifier approximate a resistive load, the source current harmonics are reduced Additionally, the triplen harmonics produced in the three phase source lines by each of the three AC to DC converters are cancelled by the triplen harmonics produced in the three phase source lines by the remaining two AC to DC converters

34 citations


Journal ArticleDOI
TL;DR: In this paper, a compact scheme using minimum integrated circuit components is described, which has a fast response for triggering angle correction and gives a full range control of voltage for three-phase SCR bridge rectifiers.
Abstract: Existing firing schemes for the firing of three-phase SCR bridge rectifiers used for industrial applications employ equidistant firing pulses. Mostly they consist of six identical phase control circuits. In this paper a compact scheme using minimum integrated circuit components is described. It has a fast response for triggering angle correction and gives a full range control of voltage.

20 citations


Patent
13 Jun 1978
TL;DR: In this paper, the authors introduce a transformer having the common point of its "Y" or "star" connected primary grounded and its ungrounded secondary coupled in open "delta" configuration to a source of measurement voltage having a second frequency significantly lower than the first or operating frequency of the transmission line system, detecting the current flowing at the second frequency and multiplying the measurement voltage injected into transmission line by the measurement current produced thereby.
Abstract: By introducing into an operating 3-phase transmission line system through a transformer having the common point of its "Y" or "star" connected primary grounded and its ungrounded secondary coupled in open "delta" configuration to a source of a measurement voltage having a second frequency significantly lower than the first or operating frequency of the transmission line system, detecting the current flowing in the transmission line system at the second frequency and multiplying the measurement voltage injected into the transmission line by the measurement current produced thereby, a d.c. component is obtained which is representative of the insulation resistance's magnitude, permitting calibration of the apparatus in terms of insulation resistance. At the same time a fault alarm system may operate with part of its circuit in common with the circuit of the resistance measuring apparatus.

15 citations


Patent
21 Feb 1978
TL;DR: In this article, a self-commutating converter for balancing an asymmetrical load which is supplied from a three-phase network is described. But the converter is not equipped with a control device.
Abstract: Apparatus for use in balancing an asymmetrical load which is supplied from a three-phase network. The apparatus is provided with a self commutating converter for generating a three-phase output current system on its a-c side which is fed with phases reversed to the network. The d-c side of the converter, in turn, is fed from a d-c source with a d-c current corresponding to the maximum asymmetry power to be balanced. The apparatus is further provided with a control device which includes a first control means having a pulse program for firing and extinguishing the valves of the converter; and a second control means responsive to the a-c voltage and a-c current of the three-phase network for determining the phase and amplitude of the required countercurrent system and for controlling the pulse widths of the pulses of the program of the first control means to effect a change in the amplitude of the fundamental of the converter three phase output current system in dependence on the determined amplitude of said counter current system and for controlling the phase of the pulse program relative to the zero crossings of the a-c voltage of the network to effect a change in the phase of the fundamental of the three phase output current system in dependence on the determined phase of the countercurrent system.

14 citations


Patent
06 Feb 1978
TL;DR: In this paper, the authors propose a circuit for detecting whether a three-phase load is correctly connected to a threephase supply employing an inductance, capacitor and resistor connected in the three branches of the load circuit so as to generate a single phase output signal.
Abstract: A circuit for detecting whether, or not, a three-phase load is correctly connected to a three-phase supply employs an inductance, capacitor and resistor connected in the three branches of the load circuit so as to generate a single phase output signal when connected to the supply, to voltage of the signal depending upon the connection to the supply The circuit requires only three wires and not connected to a ground, or neutral The output signal controls a reversing switch to ensure that the load is always automatically connected correctly; in a preferred form only one of the voltages is sufficient to light a source of radiant energy to activate a sensor to energize the reversing switch

11 citations


Patent
29 Jun 1978
TL;DR: In this paper, a load management system utilizing a three phase solid state inverter for applying a ripple signal on a high voltage line with the system having means (a) for conducting backfeed current from the line through a portion of the inverter, (b) for balancing the current and phase distribution through an isolation transformer, (c) for selectively sequentially connecting and disconnecting the transmission of the ripple signal from the high-voltage line, and (d) for providing a wide angle of conduction to assure conduction of the solid state devices over a wide time period to
Abstract: A load management system utilizing a three phase solid state inverter for applying a ripple signal on a high voltage line with the system having means (a) for conducting backfeed current from the line through a portion of the inverter, (b) for balancing the current and phase distribution through an isolation transformer, (c) for selectively sequentially connecting and disconnecting the transmission of the ripple signal from the high voltage line, (d) for providing a wide angle of conduction to assure conduction of the solid state devices over a wide time period to avoid current imbalance and core saturation.

9 citations


Patent
29 Mar 1978
TL;DR: In this article, a three-phase motor is wound with three spaced phase windings each having first and second multiple section windings, and the outer ends of the windings are connected to a two-speed switch having two different positions for alternate direct connection of the two windings to incoming phase lines.
Abstract: A three-phase motor is wound with three spaced phase windings each having first and second multiple section windings. The second winding sections of each are connected in series. The first winding has one end of all three phases connected in common. The second winding has one end connected to the common intermediate connection of the first winding sections. The outer ends of the windings are connected to a two-speed switch having two different positions for alternate direct connection of the two windings to incoming phase lines. In one position, both sections are in circuit with the three oppposite ends of the one winding connected to each other to form a second common connection. In second position, the second windings is disconnected and the first winding sections are connected in series in a star circuit, with the current flow in the two sections of each winding reversed from the first speed connection. The switch includes five separate switches, three of which have a common pole connected to a phase line and an associated high speed contact and low speed contact connected to the windings and two of which have interconnected common poles and associated contacts to the terminal ends of the second winding.

9 citations


Journal ArticleDOI
TL;DR: In this article, an instrument for simultaneous measurement of active and reactive power in a three-phase power plant connected either with three or four wires is described, with some improvements and with the use of two-stage current transformers.
Abstract: An instrument for simultaneous measurement of active and reactive power in the three-phase power plant connected either with three or four wires is described. A new, simple, electronic time-division multiplication is presented. With some improvements and with the use oftwo-stage current transformers, a very wide-range wattmeter of the accuracy class 0.1 percent has been obtained.

8 citations


Patent
20 Apr 1978
TL;DR: In this article, the three power switches (LS1-LS2) are mounted in each phase next to each other in the direction of the busbars, and the phase connection is provided before and behind the middle switch.
Abstract: There are three power switches one in each phase They are connected in series between two busbars, and there is a phase connection is provided before and behind the middle switch The three power switches (LS1-LS2) are mounted in each phase next to each other in the direction of the busbars The system is used in switching stations for three-phase overhead power systems There are several switches which give connection to earth when closed

7 citations


Patent
10 Apr 1978
TL;DR: In this article, the authors proposed a method of controlling the thyristors of an a.c. to d.c bridge converter, having neutral connected thyristor, at relatively low power levels by gating each phase leg thirristor conductive for a predetermined minimum period within the electrical separation between adjacent line to neutral phase voltages.
Abstract: A method of controlling the thyristors of an a.c. to d.c. bridge converter, having neutral connected thyristors, at relatively low power levels by gating each phase leg thyristor conductive for a predetermined minimum period within the electrical separation between adjacent line to neutral phase voltages and immediately gating the respective neutral leg thyristor conductive for the remainder of the period such that there are no intervals in the cycle when both neutral leg thyristors are in conduction. In a three phase bridge converter system, this requires at least 60 electrical degrees minimum conduction for each phase leg thyristor followed by a 60° conduction of the neutral leg thyristors. In any event, the sum of the phase leg conduction and the neutral leg conductions is always equal to 120° in a three phase system. This control method improves the response to a reverse command voltage by assuring that a phase leg thyristor is conductive, thus making a transition from the first to fourth quadrant operation at maximum possible speed.

Patent
23 Oct 1978
TL;DR: In this paper, a control arrangement for a three-phase, uninterruptible power supply generates timing signals to drive the static switches of inverters located in each phase, precisely controlling the phase differences of the inverter signals with relation to each other.
Abstract: A control arrangement for a three-phase, uninterruptible power supply generates timing signals to drive the static switches of inverters located in each phase. This control arrangement precisely controls the phase differences of the inverter signals with relation to each other so that while the overall three-phase power supplied by the inverters is nulled, power circulation through the inverters compensates for unbalanced output loads thereby maintaining balanced phase angles between the output voltage and a balanced input impedance at the input of the power supply.

Patent
08 Sep 1978
TL;DR: In this paper, the authors proposed a combination type DC power source device which comprises connecting the input side of its rectifier circuit to the output side of a main transformer 3, series-connecting an iron-cored reactor to one end of the output of the rectifier circuits and providing a changeover switch to the outputs of the reactor and which is capable of performing both CO 2 welding and gouging work.
Abstract: PURPOSE: The combination type DC power source device which comprises connecting the input side of its rectifier circuit to the output side of a main transformer 3, series-connecting an iron-cored reactor to one end of the output side of the rectifier circuit and providing a changeover switch to the output side of the reactor and which is capable of performing both CO 2 welding work and gouging work. CONSTITUTION: Three phase AC input terminals 1 are connected via power source switches 2 to the input side of a main transformer 3 which is attached, if necessary, with an output control means. The input side of a rectifier circuit 4 is connected to the output side of the main transformer 3. An iron-cored reactor 5 is series connected to one end on the output side of the rectifier circuit 4 and the output side of the reactor 5 is connected to the common end C being one pole of a changeover switch 6 which has at least two or more poles of double-throw switching functions. The other end of the output side of the rectifier circuit 4 is connected to a base metal 7. A CO 2 welding torch is connected to the terminal A and a gouging torch is connected to the terminal B. COPYRIGHT: (C)1980,JPO&Japio

Patent
26 Jan 1978
TL;DR: In this article, a method and apparatus for controlling the real and reactive power behavior of a high voltage transmission (HDT) system characterized by a rectifier station connected to a first three phase network and an inverter station connecting to a second three-phase network is presented.
Abstract: A method and apparatus for controlling the real and reactive power behavior of a high voltage transmission (HDT) system characterized by a rectifier station connected to a first three phase network and an inverter station connected to a second three phase network The rectifier and inverter stations have positive and negative station-halves connected to each other over positive and negative DC transmission lines to form positive and negative poles, each station having a common ground or return wire Each station is equipped with current and voltage regulators, as well as control angle and quenching angle regulators whereby in case of the tripping of line protective devices monitoring line current in a faulty pole, and the consequent unloading of the faulty pole, the regulation of the intact pole assumes control for a short time to protect against network transients resulting from the load drop In the event of a line disturbance, both the current set point for the current regulator and the control angle set point for the control angle regulator of the intact station-half of the intact pole are increased according to preset functions, with the control angle set point subordinated to the magnitude of the current angle set point

Journal ArticleDOI
01 Aug 1978
TL;DR: Two methods of computing the instantaneous reactive power from concurrent samples of voltages and currents are suggested and such a fast computation finds applications in protection, load behavior modelling, state estimation, reactive power compensation, etc.
Abstract: Two methods of computing the instantaneous reactive power from concurrent samples of voltages and currents are suggested. The advantages are not having to wait for a quarter of a cycle, consistency with the active power computation, and a simple measurement of the deformation factor. Such a fast computation finds applications in protection, load behavior modelling, state estimation, reactive power compensation, etc.

Patent
08 Sep 1978
TL;DR: In this paper, the power rectifier is a three phase rectifier across the output of which are connected two smoothing capacitors in series, the connection point therebetween having the common supply conductor connected therewith.
Abstract: An inverter for an x-ray diagnostic generator wherein the power rectifier is a three phase rectifier across the output of which are connected two smoothing capacitors in series, the connection point therebetween having the common supply conductor connected therewith. There is disposed in parallel with the smoothing capacitors a series circuit comprising a thyristor, two inductances, and an additional thyristor. One diode is connected in antiparallel fashion with each of the thyristors, and the connection points of the inductances and of the smoothing capacitors are connected with one another by an oscillatory capacitor. The output voltage is tapped at the oscillatory capacitor. Either single phase or three phase power may be supplied directly to the rectifier without the use of an input transformer.

Patent
26 Oct 1978
TL;DR: In this article, a control method for a three-phase self-excited inverter which is fed from a dc voltage source and in which the fundamental oscillation of the output voltage is adjustable in frequency and amplitude, in particular by the subharmonic method, is presented.
Abstract: A control method for a three-phase self-excited inverter which is fed from a dc voltage source and in which the fundamental oscillation of the output voltage is adjustable in frequency and amplitude, in particular by the subharmonic method, and wherein the pulsing or timing is always done in only one of three phases (R, S or T) such that 60°-wide pulse regions are arranged symmetric to the maximum and minimum of the fundamental voltage oscillation of each phase (R, S or T) and overlap each fundamental voltage oscillation.

Patent
18 Dec 1978
TL;DR: In this paper, a right angle connection for an SF6 -insulated high-voltage switch gear with three phase conductors is disclosed, where conductors are arranged in the connection with a straight section and an adjustable crank section.
Abstract: A right angle connection for an SF6 -insulated high-voltage switch gear with three phase conductors is disclosed. The conductors are arranged in the connection with a straight section and an adjustable crank section. The crank section is adjustable between two positions 180° apart, so that the connection can be used in either direction.

Patent
23 Mar 1978
TL;DR: In this paper, the authors proposed to reduce the magnetic unbalance between high and low main windings by arranging high pressure voltage tap windings between two divided high voltage main wires geometrically or coaxially with these windings.
Abstract: PURPOSE: To reduce the magnetic unbalance between high and low main windings by arranging high pressure voltage tap windings between two divided high voltage main windings geometrically or coaxially with these windings. CONSTITUTION: The high voltage tap winding 2 is arranged coaxially with the high voltage main windings and geometrically near the center of the high voltage windings in an arrangement of the first high voltage main winding 1A, high voltage tap winding 2, and the second main winding 1B. Electrically, the U- and W-phases high voltage tap winding 2 is connected to the Z terminal. The V phase is directly connected to the V terminal in the order of U - 1A - X, ... Z4 - 2 - Z. The tap of the two high voltage tap windings located at the same line is switched by a common load tap changeover unit. This permits the magnetic unbalance between the high and low windings to comparatively be reduced and a two phase load tap changeover unit to be shared by one unit. As a whole, the load tap of a three-phase triangular connection is enabled using two load tap changeover units. COPYRIGHT: (C)1979,JPO&Japio

Patent
02 Nov 1978
TL;DR: In this paper, an impulse generator is used to generate a sequence of pulses which are applied to a typically two phase network (R, S) through a series resistance (RK), and a detection circuit (TP) incorporating a low pass filter (C1, C2, L1, L2) and a series of linear amplifiers (IM) together with a number of sequenced switches (S1, S2, S3) provides a reading of the insulation impedance in a suitable meter (M) after filtering out noise, short term effects, and the like.
Abstract: The equipment is used for determining the insulation resistance of a multiple phase network. It can incorporate rectifiers and direct voltage components using an impulse generator and filtering detection circuit. The device can be applied to single, two or three phase networks. An impulse generator (IG) generates a sequence of pulses which are applied to a typically two phase network (R, S) through a series resistance (RK). A detection circuit (TP) incorporating a low pass filter (C1, C2, L1, L2) and a series of linear amplifiers (IM) together with a number of sequenced switches (S1, S2, S3) provides a reading of the insulation impedance in a suitable meter (M) after filtering out noise, short term effects, and the like.

Patent
28 Sep 1978
TL;DR: In this paper, a short-circuit detection and indicating system for three-phase networks with isolated or inductively earthed neutrals, operates by comparing the polarity of the first half-cycle of the charge transfer current in the neutral line-earth capacitance with the polarities measured by transformers connected to pulse circuits.
Abstract: The short-circuit detection and indicating system for three-phase networks with isolated or inductively earthed neutrals, operates by comparing the polarity of the first half-cycle of the charge transfer current in the neutral line-earth capacitance with the polarity of the first half-cycle of charge transfer current in simulated line-earth capacitance. The respective currents and their polarities are detected via transformers connected to pulse circuits. The outputs of these are connected to AND-gates and to a four-input OR-gate. The output of this is delayed and drives a monostable. One or other of two OR-gates gives a pulse to switching amplifier which energises a holding relay and corresponding signal lamp to indicate whether the short-circuit is in the direction of the line or the bus bar.

Patent
26 Jan 1978
TL;DR: In this paper, the authors propose to restrain unbalanced single phase circulating current and unbalanced three phase current, even when controlled angle would be small, and to enable to eliminate unignition of thyristor and to control till 0-180 deg.
Abstract: PURPOSE:To restrain unbalanced single phase circulating current and unbalanced three phase current, even when controlled angle would be small, and to enable to elimainate unignition of thyristor and to control till 0-180 deg., even when controlled angle world be big.

Patent
30 Nov 1978
TL;DR: In this article, the linear induction drive hovertrain is operated by a non-ferrous induction motor, which carries on-board coils to operate with special ferromagnetic loops in the track.
Abstract: The linear induction drive hovertrain is operated by a non-ferrous induction motor. The drive system carries on-board coils to operate with special ferromagnetic loops in the track. The coils are linked to a charging circuit for an on board battery to power ancillary equipment. The system provides a contactless power supply for the hovertrain, which does not affect the train drive. The system powers air conditioning, lights etc. with battery back-up when the vehicle is stationary.

01 Oct 1978
TL;DR: In this article, the authors simulate performance characteristics of three-phase induction motors under normal conditions and extreme temperature, frequency, voltage magnitude, and voltage balance, and show that the performance can be improved under extreme conditions.
Abstract: Program simulates performance characteristics of three-phase induction motors under normal conditions and extreme temperature, frequency, voltage magnitude, and voltage balance.


Patent
16 Nov 1978
TL;DR: In this article, the authors proposed to control X-ray radiation time readily and highly accurately by connecting GTOSCRs in antiparallel to at least one phase component out of three phase inputs to a boosting transformer.
Abstract: PURPOSE:To control X-ray radiation time readily and highly accurately by connecting GTOSCRs in antiparallel to at least one phase component out of three phase inputs to a boosting transformer and connecting general SCRs or diodes in antiparallel to other phases.

Journal ArticleDOI
TL;DR: In this paper, an analysis of a three-phase pulsating flow hydraulic control system is presented, which consists of five basic components: an alternator, transformers, rectifiers, a compensator and high-level high-pressure compensator.
Abstract: An analysis is presented of a three-phase pulsating flow hydraulic control system. Such a system consists of five basic components – an alternator, transformers, rectifiers, a compensator and high ...

Book ChapterDOI
01 Jan 1978
TL;DR: The Park-vector method is preferable for harmonic analysis as discussed by the authors, and the corresponding constraints of various conduction patterns are given in vector form for the voltages and currents, which can be shown on a cathode-ray oscilloscope as well.
Abstract: The three-phase semiconductor connections are built up of elementary three-phase thyristor or diode groups. Due to the cyclical symmetry of transformers or a.c. machines connected to them the application of Park-vectors and zero sequence components is rewarding. The corresponding constraints of various conduction patterns are given in vector form for the voltages and currents. The pattern will be modified on the border of the domain permitted by the semiconductors or by the firing of a thyristor. It is rather straightforward to write the proper differential equations by this method. The Park-vector method is preferable for harmonic analysis. The vectors can be shown on a cathode-ray oscilloscope as well.

Book ChapterDOI
Josef Leimgruber1
01 Jan 1978
TL;DR: A control method is presented allowing to control the synchronous motor with constant resulting flux in the machine and cosf = 1 in the whole speed and torque range, by changing the control angle in function of the state of the machine.
Abstract: In actual realizations of thyristor-controlled synchronous machines for high speed ranges, converters with D.C. link are usually applied. Normally, the converter for the synchronous motor is realized in a three phase thyristor bridge, and the gating of the thyristors is controlled by a position transducer on the rotor shaft. The reactive power for the commutation of the rectifier is supplied by the synchronous machine driving the synchronous motor in an overexcited state. The control angle of the synchronous motor, which is defined as the angle between the armature field and excitation field, is applied as constant value in actual implemented equipments, so that the synchronous motor is working by nominal power on the commutation limit line of the converter, according to the best possible cosf of the synchronous motor. In all other states it is working with a rather worse cosf than by nominal power, which represents a disadvantage of these methods. In this paper a control method is presented allowing to control the synchronous motor with constant resulting flux in the machine and cosf = 1 in the whole speed and torque range, by changing the control angle in function of the state of the machine. The condition for such an operation is a self-commutated converter on the machine side of the D.C. link. For applications, in which for reason of cost the converter with forced commutation cannot be used, a further control method is proposed, wherein the cof of the synchronous motor is optimized by maintaining the resulting flux of the machine on a constant value, so that the converter is operating on the commutation limit line within the whole speed and torque range. The control characteristics for the variation of the control angle and the excitation in function of the state of the machine are derived from the computation of the stationary characteristics of the synchronous motor. The dynamic behaviour of the synchronous motor controlled by means of these methods is depending, as shown in this paper, on a large scale on the working point of the machine. Based on the computation of the linearized transfer functions of the thyristor-controlled synchronous machine it is shown how the control parameters can be optimized for different working points by means of the state-variable representation of the process.

Patent
23 Nov 1978
TL;DR: In this article, the 3-phase staged transformer has its change over switching arranged so that delta/star change over is accomplished reliably and with relatively few components, and the change over circuit has two change over switches located one at each of two of the three corners of the delta winding configuration.
Abstract: The 3-phase staged transformer has its change over switching arranged so that delta/star change over is accomplished reliably and with relatively few components. The change over circuit has two change over switches located one at each of two of the three corners of the delta winding configuration. In the star configuration, one (5) of these change over switches is located at the neutral point whilst the other (4) is located at the voltage-end of one of the windings. The change over switches may be 2 or 3 phase.