Showing papers in "Journal of the Institution of Electrical Engineers in 1936"
37 citations
TL;DR: In this article, the importance of being able to differentiate between an increase in the power factor of a dielectric due to gaseous ionization and an increase due to other causes is emphasized.
Abstract: The importance is emphasized of being able to differentiate between an increase in the power factor of a dielectric due to gaseous ionization and an increase due to other causes. The necessity of being able to detect discharges before they have caused sufficient damage to give rise to a change in power factor is also pointed out.A description is given of various methods of discharge detection which have been investigated, together with some details of the apparatus finally adopted and used.Methods for eliminating from the measurement all discharges external to the test sample are dealt with in some detail, this being an essential feature of apparatus for use onhigh-voltage testing circuits.The last section of the paper describes some of the practical uses of the apparatus.In the Appendices the various circuit arrangements are examined mathematically, and expressions are evolved for each method which provide the means of converting the readings obtained into the actual high-frequency current flowing in the dielectric.
27 citations
TL;DR: In this article, simple formulae are developed for the effective resistance to alternating currents of tubular conductors when used under the following conditions: (a) isolated conductor, (b) single-phase system of 2 concentric conductors.
Abstract: Simple formulae are developed for the effective resistance to alternating currents of tubular conductors when used under the following conditions:- (a) Isolated conductor. (b) Single-phase system of 2 concentric conductors. (c) Single-phase system of 2 conductors of equal size laid parallel to each other. (d) Three-phase system of 3 conductors of equal size laid parallel to each other in a plane, with the middle conductor midway between the outer conductors. (e) Three-phase system of 3 conductors of equal size laid parallel to each other in triangular formation, with equal distances between conductors. In cases (a) and (b) rigid formulae are already available. The formulae developed in this paper are shown not to differ from the rigid formulae by more than a few parts in 1 000, while the reduction of labour in using the simple formulae is probably of the order of one hundredfold. In cases (c), (d), and (e), no rigid formulae are available, and the solutions put forward in this paper are the simplest and the most accurate which have yet been published. Experimental work has been undertaken to check the accuracy of the formulae and it has been found that the discrepancy between the experimental values and the calculated values is less than 3 per cent, provided that th'e ratio of diameter of conductor to spacing between axes of conductors is less than 0.85. This covers the great majority of cases occurring in practice. When the conductors are closer together than this, the errors in the formulae may be a little larger, but, even with the conductors almost touching, the greatest observed discrepancy between the experimental and calculated values of the ratio of a. c. resistance to d. c. resistance was only 6 per cent (11 per cent of the ratio of increase of resistance with a. c. to d. c. resistance).
23 citations
TL;DR: In this article, the authors describe an apparatus for the measurement of the permittivity and power factor of insulating materials over a wide range of radio frequencies, with the only changes necessary in order to proceed from one part of the range to another are changes of tuning coils.
Abstract: The paper describes apparatus devised for the measurement of the permittivity and power factor of insulating materials over a wide range of radio frequencies. The range covered is from 10 kc to 100 Me, and the same calibration the apparatus holds good over the entire range without the use of any troublesome corrections. The only changes necessary in order to proceed from one part of the range to another are changes of tuning coils. The method is that of capacitance-variation in a tuned circuit, with a thermionic voltmeter as a detector of resonance. The adjustments are made by means of two micrometer condensers, one being a plate condenser in which the sample inserted, and the other a cylindrical condenser of linear law and of very small range, which serves to measure the sharpness of resonance. Both permittivity and power factor may be obtained as the ratio of capacitance readings: frequency is not involved in their calculation, and it is this property which gives the apparatus its very large frequencyrange. The errors due to residual inductance and resistance at the highest frequencies are discussed, and it is shown that these errors, together with those associated with imperfect contact electrodes, may be eliminated, partly by very careful attention to details in the construction of the apparatus, and partly by the procedure followed in making the measurements. The apparatus is also applicable to measurements on resistors over the same range of frequencies.
23 citations
TL;DR: Capacitor voltage transformers as discussed by the authors have been proposed as a class of voltage transformer which is distinct from the conventional electromagnetic voltage transformer, and the main purpose of this paper is to establish a wider understanding of this class of transformer with view to an extension in its field of application.
Abstract: The paper describes in a general way that class of voltage transformer which the authors propose should be termed the "capacitor voltage transformer" as distinct from the conventional electromagnetic voltage transformer. No claim is made for presenting any new principles of design, the main purpose of the paper being to establish a wider understanding of this class of voltage transformer with view to an extension in its field of application. Attempt is made to define the so-termed capacitor voltage transformer and to describe the operating principles in the simplest possible manner. Accuracy characteristics are explained, especially in regard to the possibility of adjustment for service burden conditions and limitations set up by practical considerations. Typical constructional features are described and possible applications are suggested. A mathematical treatise on the theory of the capacitor voltage transformer is given in an Appendix, and a Bibliography is included.
18 citations
TL;DR: In this article, the results of an investigation into the electrical characteristics of 132-kV insulators under various weather conditions in a district subject to atmospheric pollution were given. And the steady value of leakage current of an insulator chain varies between 0.2 and 1.0 mA, depending on the weather conditions.
Abstract: The insulation of high-tension lines in industrial areas is one of the major problems in the operation of high-tension systems. This paper gives the results of an investigation into the electrical characteristics of 132-kV insulators under various weather conditions in a district subject to atmospheric pollution. It was found that the steady value of the leakage current of an insulator chain varies between 0.2 and 1.0 mA, depending on the weather conditions. In fog or with dirty insulators under humid conditions the leakage current is very unsteady and continuous surging usually takes place, the magnitude of the current-surges often reaching 100 mA. These current-surges are due to surface discharges on the insulators and are usually self-extinguishing owing to the resistance of their path being increased by the heating effect of the current, but a severe surge may develop into a complete flashover. The frequency and magnitude of these current-surges provide a criterion by which to judge the performance of insulators. Information is also given on the surface resistivity of porcelain, the characteristics of some special types of insulators, and the cleaning of insulators.
15 citations
TL;DR: In this paper, an attempt is made to discover to what extent the generation of gas of refined oils can be suppressed by the addition of relatively small quantities of aromatics, and it is shown that the aromatics present should be of the lowest boiling constituents.
Abstract: It is known that insulating oils may give off gas, chiefly hydrogen, under the influence of an electric discharge. This generation of gas is particularly marked in the case of oils which have been exhaustively refined to make them more resistant to oxidation. In this paper an attempt is made to discover to what extent the generation of gas of refined oils can be suppressed by the addition of relatively small quantities of aromatics. Insulating oils always have a more or less extensive boiling range. If it be desired to have a slight tendency to generate gas, with a relatively small percentage of aromatics, it is important that the aromatics present should be of the lowest boiling constituents.
15 citations
TL;DR: In this paper, the relation between a cylindrical magnet spinning about its axis and the currents and forces set up thereby in a neighbouring conducting circuit, of which the magnet may or may not form a part, is investigated.
Abstract: The object of these experiments is to extend certain investigations by Faraday which have been the subject of much controversy. They concern the relations between a cylindrical magnet spinning about its axis and the currents and forces set up thereby in a neighbouring conducting circuit, of which the magnet may or may not form a part. The similarity between cylindrical magnets and solenoids is examined, as well as the effect produced by one spinning magnet upon another. The bearing of these experiments upon the laws of electromagnetic induction is explained, and certain special experiments on this subject are included. The conclusions reached are given in Section (15); and in an Appendix some practical applications are described.
8 citations
TL;DR: In this article, the authors studied the variation of the ferromagnetic laminae over a frequency range from 0 to 3 × 106 cycles and found that the eddy loss observed at low frequency is different from the calculated loss, and an explanation of the effect is given.
Abstract: The paper deals with the variation of permeability and losses in ferromagnetic laminae over a frequency range from 0 to 3 × 106 cycles. After a brief description of test methods, results are given for four materials. The eddy loss observed at low frequency is shown to differ from the calculated loss, and an explanation of the effect is given. Medium-frequency performance is discussed briefly, and finally it is shown that at high frequency, permeability is influenced mainly by the depth of flux penetration in relation to the size of the selfsaturated magnetic regions. Evidence is offered tending to show that hysteresis loss is absent at high frequency, but that an increased eddy loss occurs at high frequencies from causes similar in origin to the increased loss at low frequencies.
8 citations
TL;DR: In this article, a general formula for the position of the neutral point on any system of any number of phases, balanced or unbalanced, is developed for the neutral displacement due to abnormal system conditions (other than short-circuits) known by the name of neutral in version.
Abstract: A neutral displacement due to abnormal system conditions (other than short-circuits) is known by the name of "neutral in version". This can occur as a result of open circuits in one or more phases of systems possessing inductance and capacitance, or owing to special conditions of neutral earth connections. A general formula is developed for the position of the neutral point on any system of any number of phases, balanced or unbalanced. This is then applied to deduce the neutral displacements occurring as a result of open circuits on systems fitted with neutral-earthing transformers and Petersen coils or arcing-earth suppressors. The possibility of neutral inversion on certain types of balanced system, even without open circuits, is demonstrated and a qualitative consideration of the phenomena is given. Finally, instances are mentioned of neutral inversion which has occurred in practice, and remedies are indicated, together with a summary of system arrangements to be avoided in design.
6 citations
TL;DR: In this article, the wave-shapes of impulse voltages generated in the laboratory are denned and recommendations are made for the standardization of waveshapes in order to facilitate the comparison of results obtained in different laboratories.
Abstract: Following a brief resume of available information on the wave-shapes of surges on transmission lines, the wave-shapes of impulse voltages generated in the laboratory are denned and recommendations are made for the standardization of wave-shapes in order to facilitate the comparison of results obtained in different laboratories. Standardization of impulse-testing technique is also advocated. Sparkover and puncture tests are considered in detail, and the extent of agreement of results obtained in different laboratories is indicated. Standard impulse-voltage routine and type tests are recommended for line insulators, bushings, switchgear, and transformers, and reasons are advanced for the choice of such tests. The repercussion of the introduction into national specifications of impulse-voltage testing on the existing standardized power-frequency tests is considered in detail, and recommendations are made for the elimination of some of those tests. In order to establish co-ordination between line and station apparatus under impulse voltages, a table is given showing the suggested impulse test voltages for station apparatus connected to normally-insulated transmission lines, the proposed test values being based on the British Standard Specification for line insulators now widely in use.
TL;DR: In this article, the Strowger Automatic Telephone Abstraction (SAT) was used for the protection of power networks over the signaling circuits by means of automatic telephone apparatus.
Abstract: Brief introductory remarks in Section (1) draw attention to the fact that modern centralized indicator equipment isessential for the economical operation of power distribution networks. The type of equipment described in the paper is covered by two definitions, namely centralized indication equipment and supervisory control equipment. The various facilities usually demanded in practice are outlined. The choice of method and type of signalling channel to be usedare discussed, and the need for adequate protection of the signalling channel and equipment against possible high induced voltages is emphasized. A schematic diagram of typical protective apparatus is given.Section (2) contains an outline description of Strowger automatic telephone apparatus, which is employed on the various schemes of remote supervision and control described in the paper. The characteristics of telephone type relays, polarized and non-polarized, and the operational features of the uniselector (rotary switch) and two-motion selector mechanisms are outlined. The symbols employed in the diagrams are indicated.In Section (3) the layout of centralized control rooms is discussed, with particular reference to the various types of wall and miniature diagrams employed. The layout of certain control rooms of the British grid systems are given.The operation of typical circuits employing the uniselector for the remote indication of switch position is described in detail in Section (4). The function of the repeat relay in ensuring that the indications displayed are in accordance with the actual conditions prevailing, is outlined.The various methods of remote metering, including individual selections, spot readings, and photo-telemetering, are described in Section (5).The operation of a system of engine-room telegraph signals is described in Section (6).Section (7) deals with a system of protection of power networks over the signalling circuits by means of automatic telephone apparatus. Characterized by extreme rapidity of operation, with automatic self-checking features, this system is shown adapted successfully to the inter-tripping of circuit breakers.The operational features of the fundamental circuits are described in Section (8), including the processes of selection, proving the selection, remote control of selected item, and the subsequent signalling of the indication that the intended operation has been effected.In Section (9) are described the methods of a.c. voicefrequency signalling employed in circumstances where the length of line or make-up of the signalling channel prohibits the employment of d.c. signalling.The paper finishes with a Conclusion and a Bibliography.
TL;DR: In this paper, an account of the advances in design and theory of the screened hot-wire ammeters described in 1930 is given, and the results of experience with a number of experimental instruments are given and constitute a basis for any further designs that may be required.
Abstract: This paper contains an account of the advances in design and theory of the screened hot-wire ammeters described in 1930. The design has been improved both mechanically and electrically, leading to more compact instruments of lower impedance. These improvements have arisen from a more careful consideration of the temperature distribution in the hot wire, the behaviour of the magnifying system, and the corrections necessary at high frequencies. The results of experience with a number of experimental instruments are given and constitute a basis for any further designs that may be required.
TL;DR: In this article, the authors investigated the causes of undesired changes in the capacitance and power factor of condensers and found that the changes are almost entirely due to temperature variation.
Abstract: The paper gives an account of (a) an investigation into the nature and causes of undesired changes in the capacitance and power factor of condensers, and (b) means of obtaining greater constancy. The principal results and conclusions are as follows:- The changes are almost entirely due to temperature variation. The thermal behaviour of condensers with solid dielectric is in general non-cyclic, and for a representative selection the temperature coefficients of capacitance ranged from -1800 to +200 parts in 10 6 per deg. C. The thermal behaviour of air-dielectric condensers is not cyclic in general, but more nearly cyclic than that of solid-dielectric condensers, and cyclic behaviour was obtained in some cases. The coefficients of a representative selection ranged from -65 to +150 parts in 10 6 per deg. C. Where the behaviour was cyclic, the capacitance coefficient was between 2 and 3 times that of the linear expansion of the metals used. An analysis of the causes of abnormally large coefficients showed that the variation of capacitance with air density is about 2 parts in 10 6 per deg. C. With entirely free expansion of metal plates, the coefficient is approximately that of the linear expansion of the metal, in accordance with simple theory. Variation of "fringe" and "stray" field with temperature has no appreciable effect on temperature coefficient. Change of residual internal stress in the metal plates and members with change of temperature is not in general a very important factor. Distortion due to temperature-gradients arising from inequalities of thermal characteristics of component parts is likely to be a significant factor in many cases. Variation of elasticity and moment of inertia with temperature is not significant. Unequal expansion of different parts may be a very important factor in producing large coefficients, particularly if the one set of electrodes is not quite symmetrical with respect to the other (i.e. unequal air-gaps). Even where con
TL;DR: In this article, a split-anode magnetron was used to generate continuous-wave oscillations, and it was shown that the strongest oscillations over a large range of wavelengths are produced by the same set of values of the voltage and field applied, and the second in which each wavelength has different values of voltage and fields for best results, but these sets are different for every wavelength.
Abstract: An investigation has been made of the generation of continuous-wave oscillations by a split-anode magnetron (excluding the ultra-short waves). It has been found that there are two types of oscillation: the first in which the strongest oscillations over a large range of wavelengths are produced by the same set of values of the voltage and field applied, and the second in which each wavelength has a particular set of values of voltage and field for best results, but these sets are different for every wavelength. A simple relation has been found experimentally between the wavelength, field, and voltage, in this latter case. A theory has been developed (not yet complete mathematically) to show that the first results are due to a pure negative-resistance effect, and the latter to a type of amplified negative resistance which involves a resonance. The theory is confirmed by experiments with a valve having four segments in place of two, and with a valve of larger dimensions.
TL;DR: In this paper, the effect of the illuminating engineering aspects upon the realization of the efficiency of the lamp is discussed, and the developments of the theory of street lighting which its use has brought about are indicated.
Abstract: This paper records the experience which has now been gained over three years in the use of high-pressure mercuryvapour lamps in public lighting. The engineering and photometric characteristics of the lamps and the design of the auxiliary apparatus are discussed. The overall characteristics of the lamp and its auxiliaries are given, together with certain peculiarities of street-lighting circuits which affect its performance. The effect of the illuminating engineering aspects upon the realization of the efficiency of the lamp is discussed, and the developments of the theory of street lighting which its use has brought about are indicated. Novel designs of lanterns, which are rendered necessary by the peculiar shape of the source, are described; and special optical, thermal, and constructional problems which arise from the use of the lamps, and also other points which have occurred in practical experience, are recorded.
TL;DR: In this paper, the principal materials employed for the screens in cathode-ray tubes for television and other purposes are dealt with in detail, and the method whereby the undesirable phosphorescence displayed by zinc sulphide and zinc-cadmium sulphide has been explained.
Abstract: An account is given of the principal materials employed for the screens in cathode-ray tubes for television and other purposes. The fluorescent and phosphorescent phenomena displayed by willemite, calcium tungstate and cadmium tungstate, zinc phosphate, and the various preparations of zinc sulphide and zinc-cadmium sulphide, are dealt with in detail. The method whereby the undesirable phosphorescence displayed by zinc sulphide and zinc-cadmium sulphide has been eliminated is explained. Photometric measurements of the illumination of screens composed of a variety of materials under different conditions of excitation are given. A number of spectrograms are included of the fluorescent light emitted by these substances. The results show that:? (1) Zinc sulphide and zinc-cadmium sulphide are the most suitable substances hitherto developed for fluorescent screens for cathode-ray tubes. (2) A special zinc sulphide, giving approximately white fluorescence, has been obtained. (3) A mixture of zinc sulphide and zinc-cadmium sulphide, giving a brilliant white fluorescence of high intensity, has been prepared. (4) Phosphorescence, when not required, can be entirely eliminated. (5) Zinc sulphide and zinc-cadmium sulphide giving prolonged phosphorescence can be produced, and these compounds find application for special purposes.
TL;DR: A considerable amount of work has been carried out during recent years in an endeavour to clarify this behaviour, and in consequence there has been a very noticeable tendency to develop new materials on a scientific basis as discussed by the authors.
Abstract: The chemical and physical complexity of most of the solid dielectric materials which find application in electrical engineering practice makes an understanding of their electrical behaviour an extremely difficult matter, since the phenomena underlying conduction processes even in simple solid materials are not fully understood. A considerable amount of work has been carried out during recent years in an endeavour to clarify this behaviour, and in consequence there has been a very noticeable tendency to develop new materials on a scientific basis. The present-paper is an attempt to gather together in summarized form the published information relating to this work, so that the engineer who is unable to keep in direct touch with the question may be made aware of this recent progress. This resume on solid dielectric materials should be regarded as an extension of a previous resume (Journal I.E.E., 1934, vol. 75, p. 93) dealing with liquid dielectrics.
TL;DR: In this paper, it was shown that for a metalclad and cable system, the duty on one break of a multi-break controlled- arc breaker is almost as great as for that of a single-break unit.
Abstract: The theoretical considerations in the choice of number of breaks are analysed and it is shown that, while for plain breakers multi-break construction may have its advantages, the more efficient the arc-control devices employed the less the advantages of additional breaks become with normal designs. In particular, it is shown that for a metalclad and cable system, the duty on one break of a multi-break controlled- arc breaker is almost as great as for that of a singlebreak unit. Experimental evidence in support of the theory advanced, obtained with cathode-ray equipment, is given.The development of a single-break 66-kV metalclad equipment is described, with particular reference to the interrupting ability, and test-results are given, obtained on four different short-circuit plants, showing consistent operation. The advantages to the user of the single-break oil circuit-breaker are shown by comparison with double-break designs of similar rating, and single-break layouts are described for different switching schemes and system voltages.In the Appendix an analysis is made of 3-phase cathode-ray films, showing that no leakage current is carried and that in consequence the observed reliable operation is to be expected.
TL;DR: In this article, the spontaneous fluctuation voltages generated in the anode circuit of thermionic valves are examined and an expression, equation (7), is put forward that is found to be satisfactory experimentally, provided a correction factor A is introduced.
Abstract: This paper is concerned with the spontaneous fluctuation voltages generated in the anode circuit of thermionic valves. The general behaviour of commercial valves is examined and is shown experimentally to be consistent with the existence of shot and flicker effects: an expression, equation (7), is put forward that is found to be satisfactory experimentally, provided a correction factor A is introduced. The general form of this correction factor is examined; when the operating conditions are such that flicker effect is unimportant, A is found to be independent of the type of valve used, and of the nature of the cathode surface. Under such circumstances the value of A is unity when the current is very small, and is again unity when temperature limitation is reached; it has a minimum value of about 0.1 between these limits. This minimum is independent of frequency with thoriated tungsten filaments: with oxide-coated filaments the minimum increases, and occurs at a lower current value, as the frequency of operation is decreased; this is due to flicker effect. With oxide cathodes, except at very high frequencies, A exceeds unity as temperature limitation is approached; with thoriated tungsten, however, this does not occur. At low currents the value of A is always unity, and provided the operating conditions are chosen such that A decreases as I increases, flicker effect can be ignored. The optimum operating conditions as regards signal/noise ratio usually lie in this region, and indirectly- heated oxide-coated cathodes are therefore found to be the most satisfactory on account of the high mutual conductance that can be obtained. Thus in general use the shot effect is the important limit to amplification set by the anode-circuit fluctuations. Thermal agitation in the anode stream is shown to be non-existent or negligible; interpretation of the experimental results on such a hypothesis is not self-consistent, nor is it quantitatively accurate. Fluctuation voltages due to collision ionization are not apparent, and the whole fluctuation observed experimentally can be reconciled with the existence of shot and flicker effects alone. Multi-electrode valves are also considered, and it is shown that the value of A relevant to the current leaving the cathode is sensibly independent of the electrode arrangement, and of the subsequent distribution of current between the electrodes. When the cathode stream is shared between several electrodes the current arriving at any one electrode does not necessarily yield the same value of A as that arriving at other electrodes, but in general the values are of the same order: this is explained by the existence of a fluctuating current travelling round the circuit connecting any pair of current-sharing electrodes. When such sharing occurs it is important to make the current to the actual anode a large fraction of the total current in order to preserve a high value of g2/I, and give a good signal/noise ratio. The connection of similar valves in parallel improves the signal/noise ratio.
TL;DR: A full description of welded-steel yokes or stator frames made by different manufacturers is given in this article, together with a discussion of the advantages and disadvantages of this type of frame.
Abstract: The paper describes the principal developments in inductionmotor construction which have taken place during the past few years.A full description is given of a number of welded-steel yokes or stator frames made by different manufacturers together with a discussion of the advantages and disadvantages of this type of frame.The welded-steel rotor centre or spider is similarly described in detail and discussed.The general trend of mechanical construction is outlined, together with considerations affecting enclosure and ventilation, while the construction of end-shields, pedestal-onbracket machines, and bedplates, is discussed.The magnetic forces between stator and rotor are explained and an improved expression for the calculation of unbalanced magnetic pull is developed, and extended by means of examples to show the characteristics of this type of loading.The sources of the various types of noise in an induction motor are classified and discussed.
TL;DR: In this article, the performance characteristics of voltage transformers are deduced from general fundamental principles, and expressions are derived for calculating ratio and phase errors from design data, and two methods are given for determining errors on and desired burden from a knowledge of previously ascertained test data.
Abstract: It is the aim of this paper to consider broad principles rather than manufacturing details. The performance characteristics of voltage transformers are deduced from general fundamental principles, and expressions are derived for calculating ratio and phase errors from design data. Two methods are given for determining errors on and desired burden from a knowledge of previously ascertained test data. The first method is based on ordinary graphs of errors against output, and the second method employs a simple geometrical construction based on the transformer vector-diagram. Several questions concerning the construction and practical application of voltage transformers are considered, including typical performance characteristics, voltage transformers for high frequency and high accuracy, winding connections, fuses, limiting resistances, and breakdowns, and a comparison of dry, oil-immersed, and compound-filled types. Testing is subdivided into general routine testing and testing of ratio and phase errors. Descriptions are given of two equipments for testing errors. One equipment employs a resistance potential-divider and is capable of testing ratios up to 200. The other equipment employs as potential divider a high-voltage condenser in series with a resistance and is capable of testing ratios up to 2 200. The paper concludes with some remarks on testing of errors under actual working burden, and on the effect of resistance of secondarv leads on errors.
TL;DR: In this article, a pictorial representation of what happens in thermionic valves at frequencies at which the transit times of the electrons play an important part, electron positions and velocities, in a plane parallel diode, were calculated for a succession of times.
Abstract: In order to obtain a pictorial representation of what happens in thermionic valves at frequencies at which the transit times of the electrons play an important part, electron positions and velocities, in a plane parallel diode, were calculated for a succession of timesIn the case of a saturated diode, the voltage was assumed and the current obtained from the diagram The result shows that there is an alternating component of electron current which leads the applied voltage and appears in the circuit as an addition to the geometrical capacitance current The valve, therefore, appears as a finite resistance in parallel with an effective capacitance greater than the geometrical capacitanceIn the case of the space-charge-limited diode the current was assumed and the voltage obtained from acceleration diagrams The result shows that the valve behaves as a resistance in parallel with a capacitance smaller than the geometrical capacitanceThis method has two advantages over purely analytical methods It describes the mechanism of the effects, and it shows the presence of harmonics which usually disappear in the approximations made in analysis
TL;DR: The hot-cathode grid-controlled rectifier has been used in a variety of industrial applications, such as relaying, power control, and power control as discussed by the authors, but a detailed account of the problems arising and results achieved with each application has not been attempted.
Abstract: During the past few years a variety of applications have been found for the hot-cathode grid-controlled rectifier. In the present paper a general review is made of those industrial applications which are known to be economically possible. In order that the paper may be kept to a reasonable length and of general interest, a detailed account of the problems arising and results achieved with each application has not been attempted.A brief description of this rectifier (or thyratron) is given, together with some elementary principles which must be observed when designing circuits suitable for use with it. The grid circuit, especially, gives rise to problems and operating features probably not met with hitherto in industrial control apparatus.Though originally developed as a sensitive relay, the thyratron has now reached such a stage that it is able directly to control power of some magnitude, and thus has uses other than relaying.A Table is given showing the four main groups into which applications may be classified. Examples in each of these groups are dealt with briefly.The paper concludes with the disadvantages of thyratron control, and objections which have been raised to it. An answer can be found for most of the objections raised.
TL;DR: In this paper, a high-speed continuously-evacuated cathode-ray oscillograph for the recording of high-voltage transients is described, with particular reference to the distortion inherent in the use of potential dividers.
Abstract: The paper describes a high-speed continuously-evacuated cathode-ray oscillograph for the recording of high-voltage transients; the distinctive feature of the instrument is that impulsive voltages of 100 kV to earth may be applied directly to either deflection plate singly, or +100 kV to one and ? 100 kV simultaneously to the other, without the use of a potential divider. The reasons for. and advantages accruing from, the use of such an oscillograph are discussed, with particular reference to the distortion inherent in the use of potential dividers. Precautions to be observed in the operation of the high-voltage plates are described, reference being made to the means of producing the high vacuum required in the tube. A circuit producing a delayed high-voltage impulse is shown, and the possibilities of the instrument are demonstrated by a brief investigation of the characteristics of a sphere-gap when sparking over on the front of a steep-fronted wave.
TL;DR: In this paper, the authors examined the characteristics of low-tension electricity supplies to domestic lighting and heating consumers, and proposed a method of calculating the amount of the loss, considering only cases where the principle of revenue loss can be reasonably said to apply.
Abstract: Discussion on the subject of revenue loss due to poor voltage regulation has generally been of an inconclusive nature by reason of the fact that a quantitative basis has been lacking. After making an examination of the characteristics of lowtension electricity supplies to domestic lighting and heating consumers the author puts forward a method of calculating the amount of the loss, considering only cases where the principle of revenue loss can be reasonably said to apply. The results indicate that the loss is sufficiently large to warrant closer consideration than it has hitherto been given, and in certain cases to justify expenditure on network modification, or the installation of automatic voltage-regulator equipment to prevent voltage variation. In order to show its relative importance the principle is applied to the calculations normally carried out when transformers are being purchased, and in the case considered it is shown that it completely outweighs in importance the cost of iron and copper losses.
TL;DR: In this paper, it was shown that when the anode current is very small, the fluctuation voltage is equal to that in a metallic conductor of equal resistance at a temperature about half that of the cathode.
Abstract: This paper is concerned chiefly with a discussion of whether or not the anode stream of a thermionic valve produces a component of fluctuation voltage equal to that which would be produced by a metallic conductor of equal resistance at the cathode temperature. In a recent paper, G. L. Pearson has shown that when the anode current is very small, the fluctuation voltage is equal to that in a metallic conductor of equal resistance at a temperature about half that of the cathode.In this paper it is shown that when the anode current is very small a familiar expression for the shot voltage assumes a form suggestive of a thermal-agitation voltage in a resistance at half the cathode temperature. This form is due to the dependence of anode current on cathode temperature when the anode is negative. Thus it would seem that Pearson's work does not necessarily prove that the anode stream is the seat of a thermal-agitation voltage: his results can equally well be interpreted as a shot-voltage effect, and such interpretation gives a direct explanation of why the relevant temperature is only half that of the cathode.