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This paper describes the constraints which economics places on the design of power transformers. The mathematical analysis shows how the size, losses, reactances, and power output are related when the transformer is optimally designed. Because of the number of simplifying assumptions which have been made, this paper is not a treatise on how to design power transformers. On the contrary, it is a broad view of the design problem which yields findings which are new and which seem to be borne out by the experience of transformer design engineers. The paper confirms the validity of propositions which previously had only empirical backing.

The paper contains a brief review of the thesis presented in 1933 by Mr. Kennedy and Miss Noakes in their paper before The Institution. These authors concluded that the efficiency of electricity distribution had not improved appreciably during the period 1921?31, and their hypothesis has been accepted in this paper, which consists of a review of modern factors which may be contributing to the lack of increase in the efficiency of distribution. A brief comparison is made between rural and urban areas and it is concluded that rural areas quickly become remunerative and that they are not likely to have affected the efficiency of the supply industry as a whole. The rate of increase of domestic consumption is analysed for the whole country and it is shown that the average consumption per consumer using electricity for lighting, heating, and cooking, has not increased during the period 1927?35 and that it may have actually decreased during that period, owing to the connection of large numbers of domestic consumers who use only a small quantity of electricity for the minimum purposes, and. who are not subsequently increasing their annual consumption. In order to examine the causes of this lack of development in domestic supplies an analysis is made of the average charges of each undertaking for domestic and power purposes, and the relationship between charges and consumption is also considered. The differentiation between the charges for power and domestic supplies is shown to be irrational if domestic development is envisaged on broad and progressive lines, and it is suggested that domestic supplies may be subsidizing power supplies in many instances. Finally, the factors mentioned above are shown to be likely to affect seriously the trend of supply development in the immediate future, and the conclusion is reached that the very necessary expansion of development must be controlled and directed in a more co-ordinated manner. It is suggested that the expansion of demand must be preceded by a reduction of charges for domestic supply and a halt in the downward trend of charges for power. The alteration in charges must be accompanied by a greater unification of tariffs and charges which may ultimately be achieved by voluntary arrangements between undertakings but which can only be achieved quickly by means of a single executive authority which would have the exclusive right to direct and initiate the unification of tariffs and charges. Three reasons are advanced in the paper to account for the mal-development of the domestic supplies, viz.:? (1) Prices for domestic supply are generally too high to permit of the extensive use of electricity, and reductions in price tend to follow an increased demand, instead of preceding: isfe., As a result the domestic load continues to be restricted, the fixed charges per unit sold remain high, and a condition of expanding demand with consequent falling costs becomes impossible of achievement. This is particularly true for undertakings supplying less than 10 million units per annum. (2), Electricity for power purposes is sold, in many cases, at charges which are unremunerative and which are considerably below the equivalent cost of production by private plant. The effect of this is to place on domestic charges a burden which prohibits the domestic load from increasing to the point at which its inherently high diversity makes it profitable. This applies chiefly in the case of the larger undertakings. (3) The absence of a unified tariff basis and a unified scale of charges for electricity causes anomalies and inequities which have a psychological effect in deterring consumption.

The importance of efficient maintenance of all plant for electricity distribution is paramount, for upon this depends its satisfactory performance and immunity from failure within itself. In this paper the authors discuss the influence of design and layout of plant and mains on the maintenance programme, as viewed by the distribution engineer. The experience of several London undertakings having underground cable systems for transmission and distribution at voltages of 66 kV to 0.4 kV forms the basis of this paper.

This paper discusses series street lighting circuits from the point of view of their relations to nearby telephone circuits. These lighting circuits often have a much greater inductive influence in proportion to the amount of power transmitted than have most other types of power distribution or transmission circuits. This is due to the relatively large distortion in wave shape of voltage and current on certain types of these lighting circuits, and to the unbalanced voltages to ground which occur with series layoutts. Three general types of lighting circuits are discussed. These are a-c. arc circuits, d-c. arc circuits supplied by mercury arc rectifiers, and alternating-current incandescent circuits. Of these, the incandescent type of circuit, in which the lamps are equipped with individual series transformers or auto-transformers, is the most important in this respect. Measures for reducing interference from these circuits are discussed. It is hoped that the information given in the paper will be useful to power and telephone engineers in their cooperative efforts to solve these difficulties.

An experiment in the co-ordination of electricity is now distribution is now in its fourth year in Northern Ireland of, and though the effective trading period covered is less than 3 years (from the 1st January, 1932, to the 31st october,1934) it is the object of the this paper to show that the policy of co-ordination is proving succesful and that the public has now the advantage of a service of electricity suply not possible under the previous type of control. The paper is divided into two parts, the first dealing with the general matters affecting constitution, policy, opoperations, and ultimate development; the second solely with the techinical scheme. The views and estimates given in the paper are the exprsssion of the author's opinion and are not in any away an official statement.

This paper is a study of the transmission of very large blocks of power for extraordinary distances and has for its purpose the bringing out of the major operating characteristics of such a system, the characteristics which it possesses which are different from those of shorter transmissions and the duties imposed upon generators, transformers, synchronous condensers, switches, etc., primarily as affecting their design. The paper defines a superpower transmission line as a line of great length in which the charging kilovolt-amperes per mile of length is of the same order of magnitude as the reactive kilovolt-amperes developed by the full-load line current passing through the reactance of the line and in which the resistance is small relative to the reactance. Such a line is adapted for economical transmission only for a fairly definite amount of load and any great increase or decrease below this point leads to poor economy or unstability. Since, however, the load appropriate to a given line depends upon the voltage, an appropriate line can be laid out for any reasonable amount of power to be transmitted. In order to secure a definite set of conditions to serve as a specification for determining the performance of generators, transformers etc., all applying consistently to the same system, a typical hypothethical transmission has been assumed, namely, a delivery of 400,000 kw. over a distance of 500 miles over four circuits 220,000-volt at each end.

Discussion and author's closure of a paper by L H. Hill published in the February 1935 issue, pages 154–8, and presented for oral discussion at the distribution and transmission session of the South West District meeting, Oklahoma City, Okla., April 26, 1935. F. L. Snyder (Westinghouse Elec. and Mfg. Co., Sharon, Pa.): As pointed out by the author the development of the step type voltage regulator was the natural result of the experience of both manufacturers and operators with load tap changers on power transformers. As a matter of fact, there is nothing new about the theory of a step type regulator. Several manufacturers of electrical machinery have been building step type regulators for the past 10 years and there are several million kva of installed capacity of such equipment. Step type regulators of the type which manufacturers have been building for some time have, however, been too expensive for application to distribution circuits and the step voltage regulator of the general type described in this paper consists of a smaller and less expensive regulator which can be economically justified on distribution circuits. Apparatus of the same general type as that described is being built by several other manufacturers. (See “Step Voltage Regulators,” F. L. Snyder, Electric Journal, June 1934).

The paper forms a broad survey and appraisal of progress in the public distribution of electricity in Great Britain since the industry was nationalised in 1948. A statistical analysis of the principal growth features including sales, finance and persons employed is presented. Some assessment of the progress made and the present state of development is derived from international comparisons, by considering the relative growth of public supply and private generation, and by comparing the production and use of electrical energy with other fuels, i.e. coal, gas and oil. The comparative performance of individual UK area boards is assessed on selected criteria. The statistics are presented in diagrammatic form for each of the two decades since 1948 to give some indication of trends. The authors describe the UK electricity-supply organisation, with brief references to the negotiating and consultative machinery. Changes in the pattern of area-board administration are noted, with particular reference to the evolution of district management units. The paper also deals with technical changes and progress. Reference is made to the standardisation of systems and of the underlying principles and practice of system planning, and some of the more important changes in design of distribution switchgear, transformers, cables, overhead lines and metering equipment. Improvements in constructional techniques and in operation and maintenance of the systems are also noted. A Section on research and development traces the expansion of these activities, and lists a few of the more important projects undertaken.

Before an electric arc furnace, which is a rapidly fluctuating load during part of its operating cycle, is connected to an electric power distribution system, the electrical characteristics of the furnace must be known in order that the service may be provided in such a way that the resulting voltage fluctuations on the system will not exceed allowable limits. These and related factors are discussed in this paper which outlines a general procedure that may be followed in planning electric service for such loads.

The paper gives an outline of the distributing system of the Pacific Gas and Electric Company of California which operates at 60 kv., the transformers being Y-connected, with the neutrals solidly grounded. The company considers the grounded neutral system has a number of important advantages with regard to the transformers, the transmission lines, and operation. The fewer turns of larger capacity of the Y-connected transformers and the fixed lower average voltage to ground greatly increase their reliability. The maximum voltage on the line insulators with the grounded neutral is never more than 57.7 per cent of the line voltage, and it is possible to maintain polyphase service at a substation on a branch line with only two wires in case one wire should be cut out. This cannot be done on a delta system unless one phase of the system be grounded, which is very undesirable. With a grounded neutral, a wire down is instantly detected and power must be shut off. In a delta-connected system an arcing ground is often followed by surges which break down the insulation at other points, the cause of this disturbance being the oscillatory character of the arc. In the grounded Y system no such disturbances occur, as the frequency of an arc to ground is the same as that of the system and any damage is confined to the point of failure.

In considering the subject of protecting communication circuits at electric power plants and substations by means of neutralizing transformers, this paper gives particular attention to the problems incident to the localized rise in ground potential caused by power system faults. Several specific installations are discussed and illustrated.

This paper examines problems associated with utility supply to single-phase, 60-cycle railway loads from the 3-phase utility transmission system. Supply techniques and limitations are recommended which will insure satisfactory operating conditions from both utility and railroad standpoints. Service aspects considered include: reliability and supply station facilities, phase and voltage unbalance effects, anticipated power factor, harmonics, radio, and inductive interference. There appear to be no insurmountable problems associated with supplying foreseeable railway loads from utility high-voltage transmission systems and no requirement for railroad transmission facilities or special balancing equipment exists.

THIS PAPER discusses generally the electric power distribution systems, control schemes, supervisory control, telemetering, and communication means employed on a crude-oil pipe line constructed by The Shell Pipe Line Corporation.

The problem which confronted The Philadelphia Electric Company of providing for the control of voltage and power factor of the two 66,000-volt transmission lines connecting its Schuylkill and Chester generating stations is presented in this paper. It is required that the control of voltage and power factor of the transmission lines referred to permit of the transfer of energy in either direction, at suitable power factor, up to the rated kv-a. capacity of the lines, with the generating stations operating at approximately equal bus voltages. The situation is considerably complicated by the necessity for supplying energy to several industrial substations, connected to these lines near the midpoint, which under certain operating conditions are supplied from one of the two lines. Another important factor in the selection of regulating equipment is the severe short-circuit effects possible in a system of which the ultimate capacity of the present three generating stations will be approximately 500,000 kv-a. The comparison made to determine upon the most satisfactory type of regulating equipment and the reasons for the selection of three-phase induction regulators are given. Data on the performance characteristics of the lines, with the induction regulators are included. In the discussion of this problem of voltage and power factor control, certain conclusions of a more or less fundamental character are brought out.

1. Certain experimental arrangements for an underground alternating current distribution system are covered in the paper. 2. Low costs and characteristics satisfactory for general utilization of alternating current are contrasted with difficulty of obtaining reliability. The advantage of adopting system characteristics which will make each service suitable for lighting, appliances, and motors is indicated. There is described experience with a combined light and power network on one set of mains. Effect of voltage variation on incandescent lamp illumination is discussed. An appendix covers tests on this subject. 3. Reliability in service of standard distribution materials is considered. Tests on cables are described which indicate that for underground distribution conditions, low-voltage cables will eliminate arcing faults while high-voltage cables will not do so. An appendix of arcing tests is attached. 4. Certain factors are discussed relative to size of mains and location of transformers necessary to make the low voltage network clear its own faults. 5. There is a description of an experimental system consisting of several radial high-voltage feeders, the distribution transformers of all these being connected on the low-voltage side to a common low-voltage cable network. 6. The reactance of the transformer circuits is almost three times that of standard distribution transformers. 7. The only protective devices used are automatic circuit breakers installed in the low-voltage cables between the distribution transformers and the network.

Voltage regulation on transformers under sustained load has made rapid strides in the last eight years and found very wide application in extended power systems and on industrial loads. Originally it was found economical to equip only very large transformers for load ratio control, using apparatus designed for high currents. This paper describes, and compares with earlier developments, a novel equipment of low current rating, that has been devised especially to control small blocks of power, thereby greatly widening the economic field of application of load ratio control. The electromechanical features of this equipment are stressed particularly.

This paper describes the measured properties of the electromagnetic radiation from gap-type electrical discharges which occur on distribution lines and discusses some of the factors which affect these emissions. A discussion is given of the methods by which these waves are generated, of the measurement techniques, and the findings of this investigation.

Owing to the advantages to be realized from the use of the star-star connection in interconnecting high-voltage transmission systems and from the fact that this connection requires the use of an auxiliary winding connected in delta to stabilize the neutral point or to decrease the inductance in the ground connection, a great majority of the transformers designed for interconnecting transmission lines are three-winding transformers. Another type of transformer which would be included in this general class would be that having an auxiliary winding for feeding a synchronous condenser used in controlling the voltage at the receiver end of the line. Many of the alternatives suchl as the choice between self-cooling or water-cooling, or between single-phase units and three-phase units, differ in no way from the same questions on transformers for ordinary service. However, there are a number of important features peculiar to three-winding transformers for these classes of service that complicate the design and operation to an extent that justifies special consideration of these problems. This paper will call attention to these special problems and indicate the way in which the design and performance of transformers for these classes of service are influenced by them.

Autotransformers rated at 65,000 kva recently built for use at the receiving end of the Boulder Dam-Los Angeles transmission lines are among the largest transformers so far constructed, and incorporate a number of new developments, such as a novel form of tank, an unusual arrangement of radiators and air blast equipment, and improved bushings. The design and method of shipment of these transformers are described in this paper.

During recent years, of the problems which have presented themselves to engineers on electrical transmission and distribution systems, those of voltage and switch control have probably been the most interesting. Supply systems may be classified as either rural or urban; the latter type is that on which the experience and particulars for the preparation of this paper have been obtained. It is believed that the city of Manchester is the first area to have complete automatic voltage regulation, and also supervisory control for its main substations. Some particulars of the investigations made, equipment installed, and results obtained, are given, together with a brief outline of the growth of systems, and reasons why better control of voltage is necessary. It is claimed that, by a careful application of automatically-controlled compensated voltage-regulators in main substations, the voltage on distribution networks may be economically maintained within the permissible limits of ±4 per cent; and that, generally, the voltage variation at individual services may be kept within 4 per cent overall. At the same time, the fluctuations at the secondary terminals of high-voltage power consumers' transformers may be maintained within the limits for low-voltage distribution. Abnormal cases will, however, occur and will require special treatment. The limitation of voltage variation to such a small amount possesses definite technical, economic, and psychological value; and available records over a short period suggest that it also results in increased sales of energy. The value of supervisory control is referred to, and one system is described in some detail.