Showing papers in "Transactions of The American Institute of Electrical Engineers in 1941"
TL;DR: In this paper, experiments with wire lines for this purpose and for local transmission of present-day television signals are reported, and the design and construction of the equipment used are described and its performance characteristics given.
Abstract: Intercity networks appear vital to the success of television broadcasting. Experiments with wire lines for this purpose and for local transmission of present-day television signals are reported herein. The design and construction of the equipment used are described and its performance characteristics given. The intercity lines discussed involve carrier transmission over coaxial cable with repeaters which pass a net band of about 2 3/4 megacycles. For local intracity connections video transmission of about a 4 mc band is obtained over existing telephone plant or by means of special low attenuation cable. Various circuit arrangements including the facilities used in bringing scenes from the Republican Convention in Philadelphia to the N.B.C. in New York are shown together with their overall television transmission characteristics.
151 citations
TL;DR: A comprehensive survey of principles and methods on driven ground was issued in 1918 by the Bureau of Standards as discussed by the authors, and from the measured 60-cycle values plus what experience would ensue there have been established present practices.
Abstract: I. Introduction Driven grounds are important in electric power transmission and distribution. In fact, they comprise one of the essential elements in the art of lightning protection. Yet, to this day, the value of protection derived from grounds under actual operating conditions of lightning discharge is difficult to state in full quantitative measure. And the reason for this situation lies partly in the lack of fundamental knowledge of the impulse characteristics of driven grounds. In part, the difficulty also is due to the complex factors that inherently make up driven grounds and ground systems. A comprehensive survey of principles and methods on driven grounds was issued in 1918 by the Bureau of Standards.1 Further contributions have appeared since, some presenting new developments and findings,2 others dealing on theoretical aspects of the problem,3 and a third group bearing on related questions.4 In recent years, progress has been centered on the immediate field of application. Here the emphasis has been to obtain effective service with such methods of grounding as lend themselves particularly to economical installation. For instance, a common practice with some utilities nowadays is to drive rods to considerable depths, even down to bedrock, so as to attain the lowest measurable resistance. A recognized practice for securing low-resistance grounds is also to place a sufficient number of electrodes in parallel (multiple grounds). Still another expedient is that of reducing the resistivity of the soil immediately surrounding the electrode by suitable treatment with common salt (NaCl) or other conducting solution. All these developments have been based largely either on 60-cycle values or on closely similar methods of testing. And from the measured 60-cycle values plus what experience would ensue there have been established present practices.
149 citations
TL;DR: In this paper, a short method for solving arbitrary systems of linear algebraic equations, and evaluating determinants, the quantities involved being either real or complex, is described, the cases considered are: 1. Arbitrary systems with real coefficients, which occur in obtaining stresses in structures, in solving systems of constant differential equations with constant coefficients (transient problems), etc.
Abstract: THE purpose of this paper is to describe a short method for solving arbitrary systems of linear algebraic equations, and evaluating determinants, the quantities involved being either real or complex. For proofs and for treatment of complex systems whose symmetrical coefficients are conjugate, see appendix. The cases considered are: 1. Arbitrary systems with real coefficients, which occur in obtaining stresses in structures, in solving systems of linear differential equations with constant coefficients (transient problems), etc. 2. Symmetrical systems with real coefficients, which occur with d-c networks, undamped vibration, deflections in structures, least square processes, Ritz's method, etc. 3. Symmetrical systems with complex coefficients, which occur with a-c networks, and forced vibration with dissipation. 4. Arbitrary systems with complex coefficients, which occur in certain vibration problems involving gyroscopic action. 5. Systems involving two sets of variables, which occur when the currents in a network are to be found for a variety of impressed voltages, also in the approximate solution of integral equations arising in electric field problems.
145 citations
TL;DR: In this article, a new approach is utilized which is much simpler and at the same time provides a clearer conception of the physical processes involved in the stability problem of induction motors with series capacitors connected in the supply circuit.
Abstract: INDUCTION motors with series capacitors connected in the supply circuit can under certain conditions become unstable. Upon application of the voltage the rotor will come up to partial speed and continue to rotate at this reduced speed. This phenomenon should not be confused with ferro-resonance which is accompanied by violent wave distortion, abnormally large magnetizing currents, and fluctuations in voltage. Both of these phenomena were analyzed as applied to induction motors by Butler and Concordia.1 It is the purpose of this paper to present further thoughts regarding the stability problem. A new approach is utilized which is much simpler and at the same time provides a clearer conception of the physical processes involved. Somewhat different conclusions result with the use of this analysis than with the analysis of others. In this analysis conventional induction motor nomenclature and symbols will be used as it is believed that induction motor engineers will better understand the problem by this procedure.
71 citations
TL;DR: Wagner, Wagner, McCann, and MacLane as discussed by the authors presented at the AIEE summer convention, Swampscott, Mass., June 24-28, 1940, and published in AIEE TRANSACTIONS, 1941, pages 313-28.
Abstract: Discussion and authors' closure of paper 40–107 by C. F. Wagner, G. D. McCann, and G. L. MacLane, Jr., presented at the AIEE summer convention, Swampscott, Mass., June 24–28, 1940, and published in AIEE TRANSACTIONS, 1941, pages 313–28.
63 citations
60 citations
TL;DR: In this article, a new type relay is described which, using the principle of harmonic-current restraint, is able to distinguish between the differential current due to an internal fault and that due to magnetizing inrush by their difference in wave form, operating with high speed on the fault current and being restrained from operating by the magnetizing-inrush current.
Abstract: Differential protection, employing percentage-differential relays, has1 long been the accepted method of fault protection for large power transformers. This method, illustrated by the schematic diagram, figure 1, is quite satisfactory in most respects but is subject to false tripping on the transient magnetizing-inrush current which flows when the transformer is energized. This current, since it flows in only one winding of the transformer, causes a differential current to flow which, to an ordinary relay, “looks” the same as the current due to an internal fault. One method of preventing operation on magnetizing inrush in the past has been to use slow-speed induction-type relays with long time and high current settings. This is undesirable because of the slow-speed, insensitive protection it affords on internal faults. Other methods, applied to high-speed relays, involve desensitizing the relay during a time period covering the maximum inrush transient controlled by auxiliary relays operating on the transformer voltage.2 These methods have the disadvantage that they usually require the purchase of additional potential transformers, involve one or more auxiliary relays with the attendant circuit complication, and seriously reduce the sensitivity of the protection against faults present when the transformer is energized or which occur during the inrush period. In this paper a new type relay is described which, using the principle of harmonic-current restraint,3 is able to distinguish between the differential current due to an internal fault and that due to magnetizing inrush by their difference in wave form, operating with high speed on the fault current and being restrained from operating by the magnetizing-inrush current. Being entirely current-operated, this relay does not require the purchase of potential transformers. It is entirely self-contained and the only moving part is the single relay armature which operates the tripping contacts. Minimum desensitization during the inrush period is obtained, depending on the relative magnitudes of the inrush and the fault currents.
58 citations
Journal Article•
[...]
TL;DR: A review of the literature has revealed very little information regarding the effects of small 60-cycle electric currents on man as discussed by the authors, which is not sufficient to produce unconsciousness or death but they are enough to produce involuntary muscular contractions.
Abstract: A REVIEW of the literature has revealed very little information regarding the effects of small 60-cycle electric currents on man. These currents are not sufficient to produce unconsciousness or death but they are sufficient to produce involuntary muscular contractions. The hazard to the public has been increased because of the recent development and application of electrical devices with exposed electrodes, such as the electric fence, the electric fly panel, the electric insect trap, the electric cattle prod, and the a-c welding apparatus. The fatal accidents that have occurred due to these devices have emphasized the importance of obtaining additional knowledge on electric shock. This report is based on experiments just completed on 120 men. A preliminary investigation had been made during 1936–37 on 56 men.1 Some of the data collected then have been included in the body of this paper, but not in the statistical analysis. It is hoped that the results may help to improve the design and safety of some of the new electrical devices and may be useful in clarifying the widespread misunderstanding of electric shock.
57 citations
TL;DR: In this paper, two avenues of approach are suggested for the attack of this question; first, the collection of statistical information regarding actual line performance, and second, the use of laboratory models.
Abstract: MODERN theories of direct-stroke protection premise that the ground wires are so located as to intercept the stroke and provide perfect shielding. In spite of the fundamental importance of this question there still exists considerable doubt as to the correct position of the ground wires relative to the transmission conductors. Two avenues of approach are suggested for the attack of this question; first, the collection of statistical information regarding actual line performance, and second, the use of laboratory models. Line performance is, after all, the final criterion. However, it is difficult to isolate the shielding effect from other factors which may produce outage due to lightning. Studies with models eliminate this difficulty but always contain the element of doubt as to whether the laboratory conditions are sufficiently representative of actuality as to justify general conclusions. Perhaps the best course, that which is attempted in this paper, is to try both and co-ordinate the results so obtained.
44 citations
41 citations
TL;DR: In this article, a more complete and exact criterion of instability or hunting of a synchronous machine as influenced by its armature or tie line resistance is presented, which includes in one formula three previously separately treated cases: the usual steady state power limit, rotor hunting produced by armature resistance, and selfexcitation produced by series capacitance in the armature circuit.
Abstract: This paper presents (1) a more nearly complete and exact criterion of instability or hunting of a synchronous machine as influenced by its armature or tie line resistance, (2) a general stability criterion which includes in one formula three previously separately treated cases: the usual steady state power limit, rotor hunting produced by armature resistance, and self-excitation produced by series capacitance in the armature circuit, and (3) an indication, by means of a numerical example, of the limitations of the previously used approximate criterion for hunting due to armature resistance. In previous treatments, hunting, self-excitation, and loss of synchronism have been considered only separately, neglecting their mutual interactions. The present paper, on the other hand, considers their mutual effects and thus provides a general analysis by reference to which the limitations and proper fields of application of the approximate formulas may be found. Application of the complete criterion given is however rather laborious, and it is not suggested for general use in place of the approximate forms.
TL;DR: In this paper, it was shown that impulse spark-over characteristics of electrodes with nonuniform fields cannot be represented by single volt-time curves but must be represented with volt time areas of considerable extent, which explains the large difference obtained by various laboratories when investigating sparkover between one and five micro-seconds.
Abstract: On the basis of classification of impulse wave shape, the paper shows that impulse spark-over characteristics of electrodes with nonuniform fields cannot be represented by single volt-time curves but must be represented by volt-time areas of considerable extent. This classification explains the large difference obtained by various laboratories when investigating sparkover between one and five micro- seconds. The effect of impulse generator discharge circuits in producing these differences is explained. The necessity of insulation co-ordination on the basis of volt-time areas is pointed out.
TL;DR: In this paper, the effect of transient magnetizing inrush currents on parallel-connected transformers was investigated. But the results of a mathematical analysis for the currents in the circuit under various conditions, supporting and extending the test results, are given in the appendix.
Abstract: It has long been known that transient magnetizing inrush currents, sometimes reaching magnitudes as high as eight times full-load current, may flow in a transformer winding for a period following the moment when it is energized by connecting it to an electric power circuit.1 It has not been generally appreciated, however, that other transformers already connected to the power circuit near the transformer being switched may also have transient magnetizing currents of considerable magnitude at the same time, although they themselves are not switched but remain continuously connected to the power circuit, carrying load. It has not been appreciated, moreover, that with this arrangement the transient periods of the inrush currents may be very long, the currents dying away at a much slower rate than would the inrush current of the transformer being switched if the others were not connected. This paper discusses the cause of these phenomena and describes tests made to investigate their occurrence. The results of a mathematical analysis for the currents in the circuit under various conditions, supporting and extending the test results, are given in the appendix. The amount of resistance in the transmission line circuit connecting the parallel transformers with the generating source is shown both by tests and mathematics to be a determining factor; the magnitude of the inrush current in the already connected transformers increasing to values of over twice full load current as the line resistance increases. Magnetizing inrush currents tend to operate the transformer differential relays, causing the circuit breakers to trip and remove the transformer from service when no fault exists within it. Various means have been devised to prevent the operation of the relays on magnetizing inrush current. This paper discusses the effectiveness of these various means when subjected to the inrush currents occurring with parallel-connected transformers, with particular reference to the harmonic restraint relay described in a recent paper.2
TL;DR: In this paper, measurements have been made and statistical data obtained on the multiple character and wave shape of the currents in direct strokes and the currents discharged by lightning arresters, in conjunction with other data on the field performance of arrester performance.
Abstract: In the investigation described in this paper, measurements have been made and statistical data obtained on the multiple character and wave shape of the currents in direct strokes and the currents discharged by lightning arresters. These data, in conjunction with other data on the field performance of arresters, have revealed definite differences between the nature of direct strokes and the currents they produce in arresters. 1. Arrester discharge currents have fewer components than found in direct strokes. Only about 30 per cent were found to be multiple and not over 8 components were recorded, while from 50 to 70 per cent of direct strokes were multiple with as many as 32 components recorded. 2. Components of arrester discharges are of lower crest magnitude. Only 30 per cent of those measured exceeded 1,000 amperes, while for direct strokes 50 per cent exceeded 5,000 amperes. 3. The initial high current portions of the components of arrester discharges do not vary greatly in wave shape and are similar to those of direct strokes, having for both types of discharges times to half value which, in general, lie between 25 and 100 microseconds and average about 50 microseconds. 4. The long duration low magnitude portions of direct strokes vary over wide limits, both in magnitude and duration. However, for arrester discharges they are seldom present to any appreciable degree. This portion of the discharge may have current magnitudes as high as 1,000 amperes and measurable durations from 50 to 20,000 microseconds in direct strokes, while lightning discharges through arresters seldom last more than 300 microseconds. 5. There is definite evidence that system neutral ground conditions influence the currents discharged by arresters on systems, and that the most severe duty is imposed on arresters on ungrounded systems, while the least severe service conditions appear on four-wire grounded neutral circuits. This is shown by the fact that no long duration surge components have been recorded on four-wire circuits, while about 50 per cent of the records obtained on ungrounded circuits had components of long duration. It is also shown by the performance record of the new Autovalve lightning arrester. With over 40,000 arrester years service this arrester has experienced only 18 lightning failures or a lightning failure rate of 0.045 of one per cent. Of 27,000 arrester years experience on four-wire systems there have been no failures, while of 4,500 arrester years of service on ungrounded circuits there have been 11 lightning failures. 6. There is indication that one of the factors influencing the nature of a lightning stroke is earth resistivity or geological structure. Observations lead to the inference that lightning discharges of long duration are more prevalent in regions of high earth resistivity and ancient geological structure than elsewhere. Thirteen of the 14 long duration arrester current records and 16 of the 18 arrester failures due to lightning occurred on four systems in two regions of high earth resistivity for which there was only 1,078 arrester years experience. 7. These data indicate that it is only with a combination of high earth resistivity and type of system for which the transformers cannot absorb the long duration portion, that appreciable long duration arrester discharges and accompanying severe duty on arresters is obtained. The data on which this is based are not yet conclusive, but the indications are sufficiently definite that this probability should not be overlooked.
TL;DR: In this paper, an attempt has been made to find a simple physical explanation for the positive and negative damping torques of the synchronous machine and on this basis to derive simpler formulas for the calculation of the damping torque.
Abstract: The straight mathematical analysis of the damping problem on the synchronous machine leads to very complicated results. From these results, the conception of the phenomena occurring in the machine is very difficult and in addition the formulas obtained are so long that the calculation becomes tedious and errors can easily be made. In this paper, an attempt has been made to find a simple physical explanation for the positive and negative damping torques of the synchronous machine and on this basis to derive simpler formulas for the calculation of the damping torques. It has been found that the torque of the synchronous machine, as a double-fed machine, consists of three components, two dependent on the speed of the machine and the third dependent on the angle between the rotating field and the rotor. When the synchronous machine oscillates, the change of the first two components produces positive and negative damping torques of the synchronous machine. The change of the third component produces the synchronizing torque. The positive damping torque depends mainly on the primary voltage and secondary resistance; the negative damping torque depends mainly on the excitation and the primary resistance. This knowledge made it possible to derive a simple and very accurate formula for the positive damping torque as well as a simple approximate formula for negative damping torque. On the basis of these formulas, the influence of the two axes of the machine on the damping can be easily found. A comparison between the results obtained by using the simple formulas and the long accurate formulas as well as a comparison between calculation and test on a small machine have been carried through.
TL;DR: In this article, a method for determining the effectiveness of devices used for prevention of vibration fatigue in transmission conductors is described, where measuring equipment is described which provides records of conductor vibration in the quantitative form essential for such determinations.
Abstract: A method is outlined for determining the effectiveness of devices used for prevention of vibration fatigue in transmission conductors. Measuring equipment is described which provides records of conductor vibration in the quantitative form essential for such determinations. Vibration records obtained on typical constructions are analyzed and correlated with fatigue tests and operating experience to determine the probable life of the conductor. Data are given on the performance of test spans of a special loose-core A.C.S.R., as well as A.C.S.R. of standard stranding, for various span lengths, tensions, and equipped with various devices, including a double-suspension clamp, armor rods, Stockbridge dampers and a newly-developed torsional damper. Of the devices tested, dampers are shown to be most effective in reducing vibration stresses.
TL;DR: In this paper, the effects of specific speed governors and system characteristics on over-all system performance are investigated, under certain conditions some governors may accentuate rather than reduce the magnitudes of the frequency swings, and the conditions for which this may occur.
Abstract: In the normal steady-state operation of a power system, proper load division, frequency, and time are maintained by manual or automatic system control, while the transient swings occasioned by load changes are absorbed by the inertias and speed governors of the individual generating units. With improvements in reliability and performance of systems and their interconnections, it is a natural development that further careful attention and study be given to the basic speed governors and their effects on system operation.1,5,6 It is desirable to determine the requirements which a good governing mechanism should fulfill, and the effects of specific governor and system characteristics on over-all system performance. Moreover, under certain conditions some governors may accentuate rather than reduce the magnitudes of the frequency swings, and it is desirable to know the conditions for which this may occur.
TL;DR: In this article, the double revolving field theory is used to analyze the capacitor motor operation, which is an extension of the double rotating field theory to the usual single-phase induction motor.
Abstract: Analyses of the capacitor motor operation date back to the 1920's, a pioneer effort being that of Bruderlin1 in Europe Work by Bloch,2 Biermanns,3 and others antedates that of Morrill4 in this country whose analysis has been widely used All of these have been based on the double revolving field theory, being extensions of that theory to the usual single-phase induction motor
TL;DR: In this article, the effect of the shape of the saturation curve, normal operating voltage, resistance of the winding, system capacitance, and impedance in the broken secondary or across each phase are illustrated.
Abstract: This paper presents the results of an investigation made to determine and evaluate the effect of the factors affecting neutral instability of Y-grounded potential transformer circuits. The method used employs the medium of miniature system representation. The results therefore include the effect of saturation. The effects of the shape of the saturation curve, normal operating voltage, resistance of the winding, system capacitance, and impedance in the broken ? secondary or across each phase are illustrated. Regions of instability are shown which should be avoided in applying Y-connected potential transformers as ground fault detectors. The analysis shows by means of oscillograms the conditions under which incorrect indications of faults may be obtained.
TL;DR: In this article, the authors present new data on arc-voltage drop and current-limiting effects for arc faults in bar-conductor structures, currentlimiting effect of insulated-cable arc faults, cable impedance in an iron conduit, and impedance of lowvoltage switchgear circuit assemblies, derived from tests at shortcircuit currents in circuits with open-circuit line-to-line voltages of 208-600 volts at 60 cycles.
Abstract: In the paper are presented new data on (1) arc-voltage drop and current-limiting effects for arc faults in bar-conductor structures, (2) current-limiting effect of insulated-cable arc faults, (3) cable impedance in an iron conduit, and (4) impedance of low-voltage switchgear circuit assemblies, derived from tests at short-circuit currents in circuits with open-circuit line-to-line voltages of 208-600 volts at 60 cycles. The currents ranged from less than 10,000 amperes to values as high as 100,000 amperes rms in some cases. The new data dispel several illusions with respect to accidental faults in low-voltage bus structures and other low-voltage gear. Contrary to inferences frequently drawn from previously published data, the paper shows that (a). Faults in the typical low-voltage bus structures tested are not self-clearing. (b). Fault arcs do not show the drastic current-limiting effect which they are frequently assumed to exert upon short-circuit currents. Instances are shown where actual fault currents reach 100 per cent of the rms symmetrical values calculated for bolted faults. This study shows a self-clearing tendency for representative types of accidental faults in cable, but it was found that a large current-limiting action prior to current interruption cannot be depended on. The new data, supplementing existing impedance data, definitely indicate the possibility of reasonably accurate calculation of short-circuit currents in low-voltage circuits.
TL;DR: In this article, the authors present a rigorous analysis and description of the phenomenon which takes place in an interrupting device during the interval between the parting of the contacts and the current zero at which interruption takes place.
Abstract: It is the purpose of this paper to present a rigorous analysis and description of the phenomenon which takes place in an interrupting device during the interval between the parting of the contacts and the current zero at which interruption takes place. It is to be shown that the events which take place during the arcing period prior to interruption play an important part in setting the stage for the drama of circuit interruption. This analysis has a counterpart in the phenomenon which takes place immediately following interruption; namely, circuit recovery characteristics. The knowledge of this latter phenomenon has played a dynamic role during the past ten years. With its aid, oil circuit breaker designs have advanced to the point where their excellent performance has set the high present-day standards of reliable circuit interruption.2,3 The knowledge of recovery rates4,5 laid the foundation for the displacement principle;6 namely, oil velocity multiplied by the oil dielectric (impulse) strength is equal to the maximum permissible rate of rise of recovery voltage. The stage today, however, is being set for interruptions with devices which employ air as the medium of interruption and insulation.7,8 New roles are being created. Recovery voltage, although just as important, is being assigned an easier part.
TL;DR: In this article, the authors analyzed and discussed both for existing transmission distances up to about 300 miles and for greater distance up to a full wave length; also eight different methods that have been proposed for increasing the loading per circuit or distance to which a-c power can be transmitted are discussed.
Abstract: Conventional methods of transmission are analyzed and discussed both for existing transmission distances up to about 300 miles and for greater distances up to a full wave length; also eight different methods that have been proposed for increasing the loading per circuit or distance to which a-c power can be transmitted are discussed. Of these methods, series compensation of the line reactance appears to be the most favorable for straightaway distances up to about 600 to 700 miles at 60 cycles. The problem is analyzed mathematically and with the aid of an a-c network analyzer. Curves are included which give the power limits and reactive kilovolt-ampere requirements for a large number of parameters, including the effect of distance, voltage, conductor size, series and shunt compensation, terminal impedances, and stability margin. This analysis indicates that the limitation of the transmission of a-c power greater straightaway distances than has been accomplished heretofore is primarily that of the cost of the line, the stability limitation can be overcome by a comparatively small increase in cost.
[...]
TL;DR: In this paper, the authors analyzed the response of parts of the system to changes in load, voltage, and frequency, and found that the long-time load swings are not initiated or sustained by turbine governors.
Abstract: Operating records of the Consolidated Edison Company of New York, Inc., revealed the existence of irregular fluctuations in the loads on generating stations and tie feeders. Tests were conducted to determine the response of parts of the system to changes in load, voltage, and frequency. By analyzing the test results to show the relation between these three quantities under various operating conditions, it was possible to establish the origin of the load swings, as well as to determine their magnitude, duration, and recurrence. Three general types of load swings were observed: small synchronizing power oscillations, short-time swings caused by fluctuating railroad loads, and long-time swings produced by the unco-ordinated adjustments of station loads. These swings are not initiated or sustained by the turbine governors. The synchronizing power oscillations and the short-time swings do not affect system operation, but the long-time swings do affect the loading of the tie feeders and the operation of boiler equipment. It is expected, however, that the greater appreciation of the problem derived from the tests, plus the installation of a common frequency indicator in all stations, will enable the operators to reduce the long-time load swings.
TL;DR: Clarke, Clarke, Peterson, and Light as mentioned in this paper presented at the AIEE summer convention, Swampscott, Mass., June 24-28, 1940, and published in AIEE TRANSACTIONS, 1941, pages 329-39.
Abstract: Discussion and authors' closure of paper 40–105 by Edith Clarke, H. A. Peterson, and P. H. Light, presented at the AIEE summer convention, Swampscott, Mass., June 24–28, 1940, and published in AIEE TRANSACTIONS, 1941, pages 329–39.
TL;DR: In this article, data covering nine years' oper-ating experience with 91 ultra-high-speed reclosing breaker installations mainly on a large interconnected and integrated high-voltage system are presented and analyzed.
Abstract: Data covering nine years' oper-ating experience with 91 ultrahigh-speed-reclosing breaker installations mainly on a large interconnected and integrated high-voltage system are presented and analyzed: out of 635 cases of flashover cited, 570 re-closures were successful and 65 cases of re-closure were unsuccessful, a record of 89.8-per-cent successful reclosure. Double-cir-cuit lines show a record of unsuccessful re-closure double the average but 80 per cent of the apparently unsuccessful reclosures resulted in successful reclosure of one cir-cuit. The conclusions drawn are that ultra-rapid reclosure has proved itself a tool of major importance for use in improving high-voltage line reliability; that its use can, and should be, extended to lower-voltage lines, and that further improvements are in sight as a result of recent improvements in circuit-breaker opening and reclosure time.
TL;DR: In this article, a series circuit consisting of resistance, capacitance, and nonlinear inductance was investigated with a view of determining the behavior of the subharmonic current which may result when a sine-wave voltage of fundamental frequency is applied.
Abstract: This investigation of the series circuit shown in figure 1, consisting of resistance, capacitance, and nonlinear inductance, was undertaken with a view of determining the behavior of the subharmonic current which may result when a sine-wave voltage of fundamental frequency is applied. The magnetization characteristic of the inductor is given in figure 2, and all results, therefore, are associated with this one particular inductor. All values of resistance are ohmic values.