scispace - formally typeset
Search or ask a question

Showing papers in "Journal of the Institution of Electrical Engineers in 1935"


Journal ArticleDOI
TL;DR: In this paper, a new technique of cable examination has been developed, and a diagram showing the path of failure in an actual case is given, with the conclusion that failure originates from the ionization in a void in contact with the conductor, but that subsequent breakdown takes place by carbonization of the compound.
Abstract: A new technique of cable examination has been developed. Incipient faults have been studied before actual breakdown with the aid of a microscope, the papers having been freed from oil and dyed to show up the waxing. The types of waxing observed are classified, and their part in breakdown is discussed. The deterioration is always found to be in connection with the conductor, generally through the gap of the first paper. The occurrence of the maximum deterioration at a distance from the conductor is explained, and a diagram showing the path of failure in an actual case is given. The conclusion reached is that failure originates from the ionization in a void in contact with the conductor, but that subsequent breakdown takes place by carbonization of the compound. Such carbonization requires time for its completion and is the chief factor in the voltage/time-to-breakdown curve. It takes place both longitudinally, over the surface of the paper, and perpendicularly through it. The results obtained in the laboratory are compared with those in service, and the types of failure are described. The effect of d. c. stress on cables is discussed and the advantages of routine d. c. testing of feeders are explained on this basis.

17 citations


Journal ArticleDOI
TL;DR: In this article, the limitations of existing formulae for calculating the alternating-current resistance of a "go and return" system of two parallel conductors of circular cross-section are outlined, and an improved formula is developed.
Abstract: The limitations of existing formulae for calculating the alternating-current resistance of a "go and return" system of two parallel conductors of circular cross-section are outlined, and an improved formula is developed. A table is given so that the alternating-current resistance may be evaluated in any given case in a few minutes. Experimental work was carried out to check the formula, and agreement was obtained to within 1 per cent.

15 citations


Journal ArticleDOI
TL;DR: In this paper, an approximate method is described by which the problem of thermal stability of the cylindrical dielectric of a cable can be investigated, and the post-mortem characteristics of thermal-instability failures are described, so that these can he diagnosed and distinguished from failures of the tracking and other types.
Abstract: An approximate method is described by which the problem of thermal stability of the cylindrical dielectric of a cable can be investigated. This involves the problem of deducing the dielectric loss angle against electric stress characteristic, for the given dielectric, from measurements of dielectric loss angle against voltage made upon a cable; and methods are described for carrying out this conversion. Predictions made by these methods are supported by experimental results. The post-mortem characteristics of thermal-instability failures are described, so that these can he diagnosed and distinguished from failures of the tracking and other types. An account is given of the cable failures met with in excess voltage testing in the laboratory, in which there is a transition from breakdown of the tracking type to a final breakdown by thermal instability.

11 citations


Journal ArticleDOI
TL;DR: In this paper, the performance of the spaced-aerial or Adcock direction-finder was investigated in terms of its performance under the influence of downcoming waves and its efficiency as receivers of wireless energy.
Abstract: The paper constitutes a theoretical and experimental investigation of the principal forms of the spaced-aerial or Adcock direction-finder. The analysis is concerned mainly with the determination of two important properties of the systems, namely their performance under the influence of downcoming waves and their efficiency as receivers of wireless energy. These characteristics are reduced to quantitative form by introducing the two factors named respectively "standard-wave error" and "pick-up factor," and the various aerial-system modifications are studied with the object of showing how these factors may be predicted for aay given system and how they vary with the dimensions, wavelength, and other characteristics, and also with the constants of the ground on which the aerials are erected. The four principal aerial systems dealt with are the "U" type, the elevated type, the coupled type, and the balanced type. The "standard-wave error" of the type of directionfinders which is based on the principle of the closed loop or coil is first derived theoretically; it is found to be approximately 35° for a large range of wavelengths, and to be independent of ground conductivity and dimensions of the loop within wide limits. Experimental confirmation of this is obtained on short waves (20 to 50 m). The theory of the "U" type is then considered and the method of calculating the standard-wave error for any given case is worked out. The agreement between values obtained in this way and the experimental results is satisfactory. The effect of screening the horizontal members of the system is discussed, but no quantitative formula for calculating the effect of the screen is found to be obtainable. A description is next given of a series of experiments with the "U" type on short waves, the system being tested by means of locallygenerated downcoming waves of variable polarization. This method was employed to measure the effect of screening and burying the hor

10 citations


Journal ArticleDOI
TL;DR: In this paper, the physical limitations and performance of steam and oil-electric tractors are compared, and it is shown that the limited output and poor weight efficiency of these tractors offer serious handicaps in competition with electric traction.
Abstract: Physical Characteristics of Steam, Oil-Electric, and Electric, Rail Tractors. The principal competitors of the electric tractor are the steam locomotive and the oil-electric tractor. The physical limitations and performance of these tractors are compared, and it is shown that the limited output and poor weight efficiency of the steam and oil-electric tractors offer serious handicaps in competition with electric traction. Economic Aspects of Electrification. (a) To take advantage of the superior performance of electric tractors entails large capital expenditures for track equipment and substations. An approximate equation is deduced showing that there is a permissible economic capital expenditure for electrification, in pence per ton-mile carried per annum. (b) To determine whether a railway can be equipped for electric working at a cost not exceeding this economic maximum, a hypothetical example for handling varying tonnages of goods traffic is tabulated, the costs of equipping the track for electric working are given, and the annual operating costs are compared with those for steam haulage. This demonstrates the economic feasibility of railway electrification where the traffic density is fairly high. Appendix. An appendix is added in which the physical and economic characteristics of the distribution circuits of an electric railway are discussed. It is shown that, from an economic standpoint, the single-phase system shows attractive possibilities.

9 citations


Journal ArticleDOI
TL;DR: In this paper, a new system of echo depth-sounding is described in which the sound signal is produced and the echo received by high-frequency magnetostriction oscillators by means of suitable reflectors directed towards the sea-bed.
Abstract: A new system of echo depth-sounding is described in which the sound signal is produced and the echo received by high-frequency magnetostriction oscillators. Directional properties are given to these oscillators by means of suitable reflectors directed towards the sea-bed. The echo generates in the receiver high-frequency currents, which are amplified and passed through a chemical recorder. The motor driving the recorder also controls the instant of transmission of the sound signal so that the movement of the recording stylus is synchronized with the r egular sequence of sound signals. Whilst the sound signal travels to the sea-bed and back to the ship, the recording stylus traverses a proportionate distance over the chemically prepared recording paper. Two stains are recorded at each traverse, one corresponding to the zero instant of transmission and the other to the instant of arrival of the echo. As the ship proceeds on its course, a continuous record is made which delineates the cross-section of the sea traversed by the ship. Records are reproduced to illustrate the performance of the apparatus in a laboratory tank and at se a. Good results have been obtained at depths exceeding 400 fathoms. The system is particularly suitable for sounding in very shallow water: a depth of 1 or 2 ft. can be clearly recorded.

7 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of various factors such as reactance, power factor, and automatic voltage regulation on the stability of an alternator is discussed, and it is shown that the last factor is of considerable importance in increasing the load limit and stability of a generator.
Abstract: The development of the national electricity supply scheme and the interconnection of large systems throughout Britain has brought into greater prominence problems of power limit and stability. The stability of a system depends upon the combined characteristics of the generating plant, load, and interconnecting lines. Instability may occur in excitation circuits, but this form is not to be confused with the several kinds of alternator instability which occur under different conditions of operation. An endeavour is made to give a clear review of the various forms of power limit and stability. The effect of various factors such as reactance, power factor, and automatic voltage regulation, is discussed. It is shown that the last factor is of considerable importance in increasing the load limit and stability of an alternator; and, with its use, the load of the system is limited only by the characteristics of the transmission line. Stability may be difficult to maintain under fault conditions, and high speed of operation of protective apparatus and switchgear is necessary. The practical aspect of mechanical and electrical resonance problems is briefly mentioned.

6 citations


Journal ArticleDOI
TL;DR: In this article, a detailed discussion of existing insulator designs which show improved performance under industrial deposit conditions is given, particular attention being given to utilizing "wind-washed" surfaces, and the features of design necessary to secure the maximum extent of wind-washed surface are considered.
Abstract: The paper is divided into two parts, Part 1 dealing with industrial deposits and Part 2 with saline deposits. For both parts the procedure followed is to give examples, from practice, of insulator troubles due to the deposit under consideration, and then to discuss, firstly, the mechanism of insulator failures, and, secondly, insulator designs to overcome or alleviate the troubles.In Part 1 an account is given of two 33-kV lines insulated with cap-and-pin type units. The lines are in areas where heavy industrial deposits are experienced—thus an ounce of solid matter has been collected from an insulator after it has been on the line for 6 weeks. Also the lines are in a river valley where mists are prevalent.The record of faults on these lines is given, together with an account of the procedure followed to reduce their number. It was found necessary to increase the original insulation, and the conclusion is reached that almost complete reliability of insulation has now been attained by using 4-unit suspensioninsulator strings and by carrying out one cleaning operation per year.A description and discussion are given of existing insulator designs which show improved performance under deposit conditions. New designs are described, particular attention being given to utilizing “wind-washed” surfaces. The features of design necessary to secure the maximum extent of wind-washed surface are considered. The degree of limitation imposed on the obtaining of high deposit characteristics by the existing wet-flashover requirements is discussed. Improved behaviour under industrial deposit can be obtained by sacrificing wet-flashover characteristics, but this is not recommended. Of the new designs, Designs 1, 2, and 3 have normal and Designs 5 and 6 sub-normal wet-flashover characteristics. The section dealing with new designs is, in the main, an account of development work still proceeding, rather than a record of final accomplishment. One design (Design 3) has, however, reached the stage of being tried out on a large scale on the British grid at 132 kV.Pin-type insulators are briefly considered.In Part 2, two typical examples are given of trouble due to salt on 33-kV pin-type insulators. The mechanism of failure is discussed, and it appears to be necessary to provide different designs for the two kinds of deposits. An account is given of development work resulting in an insulator which appears to have solved the trouble described in the first typical example. This insulator was unsatisfactory, however, when tried as a solution for the second example, and a suggestion is made to classify saline deposits, according to their severity, as “ordinary,” “severe,” and “extreme.” Designs of pintype insulators for extreme salt conditions are described.Ca-pand-pin type insulators are briefly considered.

5 citations


Journal ArticleDOI
TL;DR: In this paper, the limits of currentloading capacity of earth electrodes are considered under three types of conditions which may occur in practice, namely long-duration loading, where the earth current is insufficiently large to interrupt the supply; short-duration overloading, which occurs when the protective gear operates in the usual way; and long-term overloading where the circuit is earthed through a tuned reactance coil and continuous operation with an earth on one phase is possible.
Abstract: The limits of current-loading capacity of earth electrodes are considered under the three types of conditions which may occur in practice, namely long-duration loading, which occurs where the earth current is insufficiently large to interrupt the supply; short-duration overloading, which occurs when the protective gear operates in the usual way; and long-duration overloading, which occurs on the failure of the protective gear or where the circuit is earthed through a tuned reactance coil and continuous operation with an earth on one phase is possible.The behaviour of various standard forms of earth electrode is compared under the three conditions of operation, and the effect is discussed of the size and shape of the electrode and of the physical characteristics of the soil on the change of resistance and temperature-rise in the ground. The report concludes with a resume of published experimental work and a brief discussion of the effect of coke breeze and salt treatment on the loading capacity.

5 citations



Journal ArticleDOI
TL;DR: In this paper, a description of a wireless broadcasting station recently built by the British Broadcasting Corporation at Droitwich, in Worcestershire, is given, which gives a general description of the whole station, divided into four parts.
Abstract: This paper gives a description of a wireless broadcasting station recently built by the British Broadcasting Corporation at Droitwich, in Worcestershire. The station contains two transmitters, each giving a separate service, one having an aerial power of 160 kW and working on a "long" broadcasting wavelength, and the other a power of 50 kW and working on a "medium" broadcasting wavelength. The former is dealt with in greater detail than the latter, since it contains more features of technical interest. The paper, which gives a general description of the whole station, is divided into four parts. Part I deals with the objects and required performance of the station, and the effect of governmental and international regulations relating to broadcasting stations, particularly in connection with power and the choice of site. Part II gives a general explanation of the lay-out of the station, and the reasons for adopting certain types of plant. Part III deals mainly with the detailed design of certain apparatus not yet in common use, such as mercury-arc rectifiers for an output of 600 kW at 20 000 volts, and motor-generator sets for a similar output. The method of modulation adopted for the long-wave transmitter, known as "series modulation," and the design of the aerial compensating network and harmonic filter used for the long-wave transmitter, are considered at some length. The remote-control switchgear necessary for operating highpower transmitters from a central point is also dealt with. Part IV gives an account of the general performance of the station so far as it has been ascertained during preliminarytests and early transmissions for reception by the public.

Journal ArticleDOI
TL;DR: In this paper, the design, construction, and use of two-termInal resistors of calculabel reactance, covering the range 100-10 000 ohms, are described.
Abstract: The design, construction, and use of two-termInal resistors of calculabel reactance, covering the range 100-10 000 ohms are described. The resistors form a series of primary standards suitable for the measurement of residual inductance and are of two forms; those in the range 100-1 000 ohms consist of a single straight wire concentrically mounted withing a return conductor, while those in the range 1000-10000 ohms consist of single-layer solenoids similarly mounted. The former are suitable for measurements up to a frequency of 10000 cycles per sec. and the latter for measurements up to 3000 or 4000 cycles per sec. The inductances and capacitances of the standards are calculated as far as possible from their dimensions, although certain of the cpacitances involved were measured directly. The variation of reactance with frequency is discussed and experimental confirmation of theoretical predictions is given. Comparison measurements between the standards have been carried out using simple bridge methods, and the general consistency of the results shows that, using these standards and methods, the phase angle of any resistor in the range under discussion can be determined with an accuracy of 6 × 10 -6 radian at 1000 cycles per sec. even when bridge ratios as high as 10:1 are involved. As an additional check, the values of ractance were determined in terms of the constants of high-frequency self-inductance standards, and the claculated and observed results were found to show the same consistency.

Journal ArticleDOI
TL;DR: In this article, a theoretical discussion of the electromagnetic properties of aluminium-steel cored cables is given, in which the general cases of a solid and a stranded cable are discussed and the argument is extended to the more complicated case of a composite cable with a magnetic core, showing how the axial flux set up in the core by the spiralling of the outer layers will cause an increase in a.c. resistance and inductance depending on the magnetic properties of the iron and on the arrangement of the strands in the cable.
Abstract: A theoretical discussion of the electromagnetic properties of aluminium-steel cored cables is given, in which the general cases of a solid and a stranded cable are discussed and the argument is extended to the more complicated case of a composite cable with a magnetic core, showing how the axial flux set up in the core by the spiralling of the outer layers will cause an increase in a.c. resistance and inductance depending on the magnetic properties of the iron and on the arrangement of the strands in the cable. For the special case when, owing to the spiralling of the two outer layers being in opposite directions, the flux in the core becomes negligible, the inductance may be calculated from the dimensions of the cable and the a. c. resistance from the conductivities of the components. The experimental work in verification and extension of the theoretical analysis consisted of the measurement of the d. c. and a. c. resistance and inductance, at commercial frequencies, of a short length of transmission line, short-circuited at the end over a wide range of currents by means of the Gall-Tinsley alternating-current potentiometer. This instrument was made the basis of an arrangement designed to make such measurements a matter of routine, while attaining an accuracy of the order ± ? per cent. Further tests were made to determine the flux existing in the steel core by measuring the voltage induced in a search coil. The results are discussed in the light of the theoretical analysis and of American practice, and definite figures are established for the British Standard conductors.

Journal ArticleDOI
TL;DR: In this paper, a comparison of the costs of power production for normal power requirements up to 500 kW is made, and the results are given for an investigation into power-plant costs which was made in the area of a semirural supply undertaking.
Abstract: The general purpose of the paper is to make a comparison of the costs of power production for normal power requirements up to 500 kW. Power from private plants is considered first and the results are given for an investigation into power-plant costs which was made in the area of a semirural supply undertaking. A more generalized study of the cost of running Diesel and "pass out" steam plant is then made, as these werfe found to be the most efficient forms of private plant. The second part of the paper is devoted to an analysis of the costs of providing electricity from public-supply undertakings. The particular case of an actual semi-rural undertaking is studied (in whose area the private-plant investigation was made), and the technical design, progress, and costs, are detailed for this scheme. Private-plant and public-supply costs are then compared for this particular case. Finally, a brief classification is made of the various types of supply undertakings, and the generalized costs for private plants are compared with the general case for the public supply. The conclusion is reached that a modern and efficient public-supply undertaking can supply power more cheaply than the most efficient private plant, except for those special cases which are outside the scope of this paper. It is found that public-supply tariffs are widely dissimilar, although the capital expenditure per consumer is shown to be approximately the same for all types of areas. These variations in cost are due in part to varying stages of developments between undertakings, but chiefly to the lack of a standard tariff basis, and it is suggested that national co-ordination of tariffs is essential if increased sales are to be obtained.

Journal ArticleDOI
TL;DR: In this paper, the authors reviewed the early development of the central station with its isolated lowvoltage distribution system (compulsorily underground) at a time when every discouragement was given to the establishment of large areas.
Abstract: After a short Introduction putting on record the legal basis of public electricity supply, the author reviews the early development of the central station with its isolated lowvoltage distribution system (compulsorily underground) at a time when every discouragement was given to the establishment of large areas. Power companies commenced in 1900, and the first provision for combination for generation and bulk supplies appeared in the 1909 Act.The effect of recent legislation (1919 to 1926) is shown to be almost entirely that of improving generation. This legislation, culminating in the setting-up of the Central Electricity Board and the grid, leaves distribution in much the same legal position as in 1899. It is shown that undertakings are essentially what the law makes them.The paralysing effect of the 1888 purchase terms upon companies approaching the purchase date is demonstrated, and remedies are suggested. The unsuitability of the 1926 Act (Section 39) in regard to provisions for companies with large areas is indicated.The moulding effect of the grid tariff upon the form of retail tariffs is brought out, and the potential advantages ofthe grid in encouraging new undertakings are suggested.The subjects of the standardization of charges, and of the right of the consumer to a supply, are discussed.The basis, growth, and effect of the General Regulations and the Overhead Regulations are traced, in relation to equipment and also as to consumers and their wiring, connection, and disconnection.The Electricity Commissioners' 1934 Regulations are discussed, especially in view of their proposed reconsideration.The Paper closes with a list of distribution matters which it is suggested should be dealt with in a Consolidating and Amending Act.

Journal ArticleDOI
TL;DR: In this paper, a demountable thermionic valves are evacuated continuously by means of oil condensation pumps, which is a technique used in the field of thermionic valve repair.
Abstract: This paper describes demountable thermionic valves evacuated continuously by means of oil condensation pumps.


Journal ArticleDOI
TL;DR: The method employed is shown to combine to a high degree the flexibility and immediate response of the best type of officer control with the definite and highly visible indication of signal control.
Abstract: The author discusses the control of road traffic by traffic officer and by time-controlled. signals, and from their advantages and limitations deduces the fundamental requirements of a system operating automatically by vehicle actuation. These requirements, which arise directly from the problem of ensuring adequate safety with maximum traffic circulation at road intersections of widely diverse characteristics, are enumerated, and a detailed description is given of a method by which they are attained in practice. The method employed is shown to combine to a high degree the flexibility and immediate response of the best type of officer control with the definite and highly visible indication of signal control. Methods by which the basic system may be modified to meet special cases are also dealt with, and the author concludes by indicating that control must shortly be considered in relation to complete areas rather than to the single intersection.

Journal ArticleDOI
TL;DR: In this paper, a method for direct measurement of the quantities involved in the a.c. permeability of a specimen, namely Bmax. and Hmax, is described, and applied in an investigation of the dependence of commercial sheet materials on frequency and wave-shape at power and telephonic frequencies.
Abstract: A method for the direct measurement of the quantities involved in the a.c. permeability of a specimen, namely Bmax. and Hmax., is described. It is applied in an investigation of the dependence of the a.c. permeability of commercial sheet materials on frequency and wave-shape at power and telephonic frequencies. In agreement with other observers, the effect of frequency is found to be neglible up to 500 cycles per sec. apart from a reduction, attributable to eddy currents, at magnetizing forces for which the permeability is high. Tests on a range of specimens with magnetizations giving wave-shape conditions varying between sinusoidal voltage and sinusoidal current, failed to show the increased permeability with approximation to a sinusoidal current wave which was observed by Lombardi and McLachlan. Within the accuracy of the measurements, the permeability appeared independent of wave-shape between these two practical limiting conditions. In the second part of the paper a comparison between the results of loss measurements on magnetic meterials by bridge and wattmeter methods is described. The discrepancies observed are shown to be entirely attributable to the errors in the bridge results due to the presence of harmonics, and the conditions under which the bridge method may be used satisfactorily for iron-testing, at both power and telephonic frequencies, are deduced.

Journal ArticleDOI
TL;DR: In this article, the authors discussed the various forces which give rise to stresses and deflection in large electrical machine frames. And they showed that the latter forces are by far the more important.
Abstract: In this paper the author discusses the various forces which give rise to stresses and deflections in large electrical machine frames. The mechanical or static loading is treated, and then the forces due to magnetic loading are examined. It is shown that the latter forces are by far the more important. The tendency for the rotors of induction motors to pullover to the stator is explained by means of a graph, and it is shown how a machine can be so designed as to avoid this trouble. It is pointed out that the frame of a machine is under the action of a total magnetic pull equal in most cases to 10 times the "unbalanced magnetic pull" calculated for a rotor displacement of 10 per cent of the radial air-gap. This particular problem is examined by means of photoelastic tests taken upon celluloid models, and the effect of the spread of the frame feet is very clearly demonstrated. A comparison is made between these tests and the calculated bending-moment diagram. In an Appendix the author gives a mathematical solution of the problem, the unbalanced magnetic pull being considered as a concentrated load, and a number of curves are included in order to simplify the calculation of stresses and deflections. The points of zero bending moment are also given, so that the complete bending moment diagram can be rapidly drawn for any case. In conclusion, an actual example is worked out in detail, and it is shown that an induction motor frame has to be so designed as to limit the deflection; the stresses are very low and of the order of 2 000 lb. per sq. in. or less. Machines with large air-gaps are designed on a basis of limiting stress, which occurs long before the limiting deflectionis reached.

Journal ArticleDOI
TL;DR: In this article, a detailed investigation of the fundamental dielectric propeities of paper was carried out under carefully controlled conditions covering a very wide range, on three representative kinds of paper, both in the dry condition, and after impregnation with oil.
Abstract: This paper is an outline of a detailed investigation of the fundamental dielectric propeities of paper. Measurements were made under carefully controlled conditions covering a very wide range, on three representative kinds of paper, both in the dry condition, and after impregnation with oil. The currents flowing through the material under various conditions were found to be affected in widely different ways by changes of moisture content, temperature, and voltage. The laws governing the various changes lead to the following conclusions. Power-loss phenomena under ordinary conditions are manifestations of dielectric absorption obeying Hopkinson's laws. The part played by normal conduction (leakage) in power-loss phenomena is usually negligible, but it is likely to be the determining factor in the breakdown of paper at high voltages. Impregnation with transformer oil merely serves to exclude moisture: it does not appreciably affect thebasic properties of the paper.

Journal ArticleDOI
TL;DR: In this paper, the conductivity and power factor of transformer oil at high stresses were investigated and it was found that the relation between the applied voltage and the conduction current under direct stresses between 50 and 300 volts per mil can be expressed by the equation I = kVm, where m is approximately 3.m.
Abstract: Experiments have been carried out to investigate the conductivity and power factor of transformer oil at high stresses. It has been found that the relation between the applied voltage (V) and the conduction current (I) under direct stresses between 50 and 300 volts per mil can be expressed by the equation I = kVm, where m is approximately 3. At stresses between 50 and 120 volts per mil, the relation may be expressed more accurately by the equation V = V0 + nI. The specific resistance of pure transformer oil at a stress of 50 volts per mil is greater than 4 × 109 megohms per cm cube. The power factor of pure transformer oil is of the order of 0.00005 at stresses under 70 volts per mil (r.m.s.), but above this stress is increases rapidly. It is suggested that the observed results can be explained by a theory of ionization by collision at high stresses.

Journal ArticleDOI
TL;DR: In this article, the authors present information relating to the detail design of overhead lines for rural distribution, in a form which it is hoped may prove easy of application, and thus obviate many of the tedious calculations above referred to.
Abstract: The available data relating to the detail design of rural distribution lines are very limited and scattered, and only to be found by prolonged search through numerous technical journals, manufacturers' lists, and the usual textbooks. They refer primarily to individual fittings, or alternatively to basic principles. Although the principles involved are in the main simple, the calculations are often in their practical application lengthy and tedious. All overhead transmission or distribution lines in this country must be designed to comply with the Regulations for Overhead Lines El. C. 53, prescribed by the Electricity Commissioners for securing the safety of the public. Thebasic factors of design are therefore common to various types of construction, even though the detail design may vary considerably. The prime purpose of this paper is to present information relating to the detail design of overhead lines for rural distribution, in a form which it is hoped may prove easy of application, and thus obviate many of the tedious calculations above referred to. An attempt has been made to simplify and clarify the application of basic principles by means of a series of tables and graphs, which enable one to determine at a glance the final results, in much the same way as the complexities of the properties of steam have been clarified in the entropy diagram, or the effect of money rates operating over a number of years, as readily seen in interest or discount tables. The form of presentation of much of the data is originaland no attempt has been made to include the usually accepted formulae or fundamental principles, details of which may be found in any reliable textbook. Similarly, details of the official regulations relating to overhead lines are not included, as they are covered in the Electricity Commissioners' Regulations El. C. 53 and Explanatory Memorandum El. C. 53A. The paper is divided into two parts, the first being a series of tables and graphs covering various aspects of line design, the second describing a number of practical details of design which have proved efficient in service. It is hoped that the form of presentation may appeal to the busy engineer, and in particular to those who may be responsible for the design and erection of both high and low-voltage overhead distribution lines.

Journal ArticleDOI
TL;DR: In this paper, the hysteresis coefficients for cobalt steel, aluminium-nickel (Al-Ni) and magnetic silver alloys were determined experimentally and the test methods used in the laboratory for measuring the various torques are explained.
Abstract: The paper deals with small self-starting synchronous motors such as are employed in time switches, meters, recording instruments, and other timing devices.In order to keep the paper within reasonable bounds it was felt generally advisable to confine the notes to selfstarting motors, since they are of more general application. The small hand-starting motors as used in domestic clocks, and any device which requires external starting means, are excluded.The paper gives a resume of some designs available, and includes general test-results obtained.It then continues with detailed data on the hysteresis type of motor recently investigated by the authors, and endeavours from the results obtained to substantiate Steinmetz's theory of this type of motor expounded in 1900. Various new materials, such as cobalt steel, aluminium-nickel (Al-Ni) steel, and magnetic silver alloys, are considered.The hysteresis coefficients for cobalt steel and aluminium-nickel steel were determined experimentally and are given.The nine designs described are chosen to give typical examples of the designs available, and in the short description of each some of the difficulties of design and manufacture are explained.The question of running-in torque, which is a very important factor to be considered, has been thoroughly investigated.The use of permanent magnets as synchronous-motor rotors has been studied from theoretical and practical viewpoints, and the conclusions are given.The requirements of the motor bearings are stated and typical examples are shown.The test methods used in the laboratory for measuring the various torques are explained.The test figures and curves given are those obtained by the authors from the particular models available in the laboratory. They may not, however, represent the maximum figures obtainable, as it is quite conceivable that variable results may be obtained due to inconsistencies in manufacture.In conclusion, brief notes will be found of some specialized applications of these small motors.

Journal ArticleDOI
TL;DR: In this paper, the growth in the use of electrical energy in the Soviet Union in connection with industrial development schemes of the Soviet Government is outlined, and details are included of developments in peat fuel in large power stations.
Abstract: The growth in the use of electrical energy in the Soviet Union in connection with the industrial development schemes of the Soviet Government is outlined, and details are included of developments in the use of peat fuel in large power stations. Some particulars are given of the thermal-electric power stations which are being built in many parts of the Union, and of the hydro-electric developments of the electrification authorities. Some outputs are shown for 10 stations where British plant is installed.Particulars and illustrations are given showing the trend of the general lay-out of power stations, together with details of a typical station designed for an installed generating capacity of 250 000 kW. Four stations of this type are now under construction.The standardization work of the Soviet authoritis in relation to generating, transforming, and transmission equipment, is outlined.The paper terminates with a brief reference to electrical manufacturing developments, railway electrification, and research.

Journal ArticleDOI
TL;DR: In this paper, the authors discuss the advantages of propeller fans as applied to the cooling of electrical machines, and point out that the windage efficiency of a machine with fan is far more important than that of the fan alone.
Abstract: In a recent paper the author dealt with the design of propeller fans, and in the present paper he discusses the advantages of propeller fans as applied to the cooling of electrical machinesIllustrations are given of various types of electrical machines fitted with propeller fans, and the author points out the flexibility of design as compared with that of the centrifugal fanSpecial tests show the advantages of a fan designed according to modern aerodynamics over the simple “paddle wheel” type of fan Reference is made to fans designed to give maximum slip-stream rotation The author points out that the windage efficiency of a machine with fan is far more important than that of the fan alone, and the most efficient fan does not necessarily give the most efficient machine Great care must be taken in computing from friction and windage tests the actual power taken by the fan The fan can be designed to rotate the air more efficiently than can the machine itself, so that the increased fan power may be more than balanced by the reduced machine windageThe author stresses the need for good inlet conditions for the satisfactory operation of propeller fans Tests made upon a turbo-alternator illustrate the effect of guide vanes in the air intake to propeller fans, and the author points out that both circumferential and radial guide vanes are essentialDiscussing the problem of external fans for cooling large turbo-alternators, the author shows that two fans in series on a variable load permit greater efficiencies, and therefore greater flexibility, than two fans in parallelTests on two propeller fans in series bear out the author's statementsHigh efficiencies are claimed for a special scheme of series propeller fans which simplifies the dampers in a turbo-alternator ventilation scheme

Journal ArticleDOI
TL;DR: In this paper, a review of the progress made in simplifying the design and reducing the cost of rural distribution equipment is presented, and the advantages of single-phase distribution are enumerated.
Abstract: The purpose of this paper is to review the progress made in simplifying the design and reducing the cost of rural distribution equipment. Comparisons are made of 11 000-volt distribution lines using various types of conductors. The advantages of single-phase distribution are enumerated. The design of transformers and their capital and running costs are considered, and suggestions are made for standardization of sizes. Methods of obtaining cheap and reliable protection on the h. t. system by means of simple switchgear and fusegear are illustrated. Particulars and costs of various types of l. t. distribution mains and services are given. The difficulties encountered in some rural districts in obtaining adequate earths are recorded, and a strong recommendation is made that ?all insulated? installations be adopted wherever practicable, and that in all other cases earth-leakage switches be employed.

Journal ArticleDOI
TL;DR: If the proposed adaptations for limiting the frequency band-width of transmission were adopted, spectrum overlap could be greatly minimized and transmission conditions would be more favourable to high-fidelity reception than they are to-day.
Abstract: Wireless broadcasting technique is hampered because of the scarcity of channels and the multiplicity of transmitting stations. The spectra of frequencies radiated by stations occupying frequency-contiguous channels overlap, and the audio-frequency, output from the receiver which is designed for ordinary domestic reception must be limited to meet the existing conditions of transmission. It is improbable that European nations will agree to limit either the existing power or the number of working stations; but, if it were possible to modify transmitters so that the spectrum of frequencies radiated contained the carrier and only one set of side-bands, spectrum overlap would be avoided or minimized. The paper sets out suggestions for limiting the frequency band-width of transmission by methods which are neither elaborate nor costly and which could be easily incorporated in existing transmitter circuits. It is shown, also, that the adoption of the suggested technique would not cause service dislocation. A quantitative analysis indicates that, although the proposed adaptations do not limit the transmitted spectrum to a band width containing only the carrier and one set of side-bands, and although the transmission of certain vestigial side-bands is essential to the method, nevertheless, if the methods were adopted, spectrum overlap could be greatly minimized and transmission conditions would be more favourable to high-fidelity reception than they are to-day.

Journal ArticleDOI
TL;DR: In this paper, a description of an oscillograph equipment for high recording speeds incorporating a recently developed type of highvoltage, gas-filled, cold-cathode, sealed-glass oscillograph tube, and therefore requiring no pumps.
Abstract: A description is given of an oscillograph equipment for high recording speeds incorporating a recently developed type of high-voltage, gas-filled, cold-cathode, sealed-glass oscillograph tube, and therefore requiring no pumps. Constructional details and characteristics of the tubes and all accompanying accessories necessary for the operation of the oscillograph, with their arrangement in a common housing, are given. The means of beam control are described; also the mode of action of electromagnetic and of electrostatic deflection circuits for cyclic and single-sweep phenomena, and for controlled and uncontrolled events, is explained. Specimen oscillograms illustrating each case are given. As far as possible, the more recent features only of cathode-ray oscillograph technique are emphasized.

Journal ArticleDOI
TL;DR: In this article, the two sources of error experienced when using peak voltmeters at frequencies of 20 megacycles per sec. or higher were investigated, namely, the error due to resonance and that due to the time of flight of the'electrons from anode to cathode in the rectifying diode.
Abstract: This paper refers to the two sources of error experienced when using peak voltmeters at frequencies of 20 megacycles per sec. or higher, namely, the error due to resonance and that due to the time of flight of the'electrons from anode to cathode in the rectifying diode. In the case of the parallel-plane diode the latter appears to impose the severer limitation, and it is shown that very short times of flight are necessary. An approximate method of estimating this error with diodes of other geometric form is suggested, and a convenient arrangement of peak voltmeter for use at high frequencies is described.