DOI:10.1049/ji-2.1946.0017

出版商:IEE    

年代:1946

数据来源: IET

摘要:

The paper reviews the progress that has taken place in the last 15 years in the design of the steel-tower high-voltage transmission lines of the Central Electricity Board. Lines operating at 132 kV are dealt with separately from those operating at 66 kV and 33 kV.Changes in conductors, joints, insulators and towers have been made in the light of experience, and a record of these is given as well as of other improvements of a minor character.The behaviour of s.c.a. conductor and the methods employed for jointing it are described in detail, and alternative copper conductors are also mentioned. The development of new types of insulators to suit operating conditions in the country is described.The steps taken to reduce the effect of lightning, e.g. more effective earthing, gap control, and the limited use of double earth-wires, are covered, and alterations in towers which have proved advisable are detailed.

DOI:10.1049/ji-2.1946.0018

出版商:IEE    

年代:1946

数据来源: IET

摘要:

The impulse breakdown of short gaps between spheres is greatly affected by the amount of irradiation present, and recommendations are made in the British Standard “Rules for the Measurement of Voltage with Sphere-Gaps”1that appropriate precautions should be taken when voltages of less than 50 kV (peak) are being measured. These precautions are generally considered to be unnecessary in the measurement of higher voltages, and, in most laboratories, no deliberate steps are taken to provide irradiation.In a previous publication the author has shown that appreciable errors may be incurred if irradiation is not used with spheres of 6.25 cm diameter in the measurement of voltages up to 100 kV (peak). Further measurements have now been made up to 400 kV (peak) with 1/5 and 1/50 impulse voltage waves, of positive and negative polarities, for spheres of 6.25 cm, 12.5 cm and 25 cm diameter. The present results confirm and extend the previous observations.The irradiation provided by the ultra-violet illumination from the impulse generator spark-gaps has a marked influence on the behaviour of the sphere-gap, in the absence of other forms of irradiation, and consequently the position of the sphere-gap relative to the impulse generator is observed to affect the results. This factor does not appear to have been considered in other laboratories, and it may explain some of the differences between the results obtained by various investigators in the calibration of the sphere-gap with impulse voltages.As it is not always convenient to illuminate the gap with the light from the impulse generator spark-gaps, the irradiation provided by the insertion of 0.5 mg of radium in the high-voltage sphere has been examined and is found to give satisfactory results. Measurements of the impulse breakdown of the unirradiated sphere-gap show that there is a gradual transition from the voltage which causes breakdown for 10% of the applied impulses to that which causes 90% breakdown, whereas a sharply defined breakdown voltage is obtained when the gap is irradiated. The mean breakdown voltage of the unirradiated gap exceeds that of the irradiated gap by an amount which varies with the gap length. For a 3 cm gap between 12.5 cm diameter spheres, breakdown of the unirradiated gap takes place at a mean voltage about 13% in excess of that for the irradiated gap. With larger gaps, for which a difference between the breakdown voltages for positive and negative impulses is recorded when one sphere is earthed, the difference is found to be largely influenced by irradiation. The mean breakdown voltage for an unirradiated gap of 9 cm between 12.5 cm diameter spheres is 20% higher than the irradiated value for a positive impulse, and 1.5% higher for a negative impulse. The negative impulse breakdown voltages agree closely with the corresponding values given in the B.S. 358 Tables, whereas the voltages given in the Tables for the positive impulse breakdown are intermediate between those obtained in the present experiments for the unirradiated and the irradiated gaps.The results show that some revision of the Standard Rules for the use of sphere-gaps is necessary, and, in particular, that more definite recommendations should be made concerning irradiation. Further, it is evident that the influence of irradiation is an important factor to be considered in the breakdown of other forms of discharge gaps in which corona is not observed to precede breakdown. Also, the breakdown of discharge gaps on the wavefront may be expected to be governed largely by the amount of irradiation present, and, though his has been realized by many workers for short gaps, no consideration appears to have been given to irradiation in the measurement of wavefront breakdown for longer gaps.

DOI:10.1049/ji-2.1946.0021

出版商:IEE    

年代:1946

数据来源: IET

摘要:

The paper first refers to the Ferraris-Arno system of single-phase to 3-phase conversion, giving the reasons for its popularity. This introduction is followed by a description of the system with a reference to Prof. Arno, its inventor, and then by a more detailed description of how the phase convertor or “pilot motor” functions. Limitations of the simple Ferraris-Arno system are enumerated.The capacitor Ferraris-Arno system, which is a development of recent years and posseses advantages over the conventional system, is described. Then follows a description of the multi-capacitor Ferraris-Arno system which is a logical development of the capacitor system.Reference is made to the system as a means of solving certain single-phase motive-power problems, and a system designed to give very close voltage regulation when required is described briefly.

DOI:10.1049/ji-2.1946.0030

出版商:IEE    

年代:1946

数据来源: IET

摘要:

Five papers have been read before The Institution within recent years dealing with capitalization or the economics of engineering. The authors of all these papers were in agreement upon the fundamental principles and differed only in their application. On the other hand, not only were the discussions vigorous and comprehensive in commenting upon the different views of application, but also, and surprisingly, they sharply criticized the principles themselves. As a final result, the present position of capitalization is in a cloud of confusion. Its importance in affecting the finance and economy of electrical engineering operations is such that the matter should, if possible, be clarified. The purpose of this paper is to summarize the present position and therefrom to make new suggestions regarding the interpretation and application of the principles involved.

DOI:10.1049/ji-2.1946.0031

出版商:IEE    

年代:1946

数据来源: IET

摘要:

Discrepancies between the calculated performance of machinery and apparatus and the corresponding measured or actual values are due either to errors in design and construction—referred to as consistent errors—or to uncontrollable variations and irregularities in the materials and manufacturing processes. The latter are distinct from the former in that they are governed by the vagaries of chance. They are responsible for the difficulty in giving guaranteed values for technical performance and thence for the introduction of tolerances on these guarantees.Tolerances have always been, and still are, a vexed question between manufacturers and purchasers—partly because the purchaser naturally prefers a definite guarantee and partly because tolerances are often associated with commercial astuteness, ignorance in design or incompetence in manufacture. This view may, but should not, be justified.For apparatus in mass production the probability distribution can be determined by direct analysis of the performance for each product. This direct method is not applicable to most engineering machinery since the quantity production of identical units is too small. The paper discusses the various factors involved in the determination of performance guarantees and develops practical methods for assessing these considerations and deriving therefrom appropriate values both of guarantee and, if necessary, of tolerance.Modern methods of production are assumed in which the principles of quality control are applied to the manufacture of component items in both material and labour.

DOI:10.1049/ji-2.1946.0032

出版商:IEE    

年代:1946

数据来源: IET

摘要:

After nearly six years of blackout conditions, street lighting in this country is to be recommissioned on pre-war standards. This will initiate a period of development of new or improved lighting in which the electrical industry will play a leading part. The paper has been written to promote a discussion of the various factors to be considered in connection with street lighting.A brief introduction and a reference to the need for adequate street lighting are followed by a consideration of the illumination requirements. Agreement throughout the electrical industry is desirable on the theoretical considerations governing good visibility; the provision of adequate “background brightness” should be a basic aim. Street-lighting appliances, lanterns, sources and control gear are discussed.The legal position of lighting authorities in relation to street lighting is briefly reviewed. Annual running costs are analysed and are applied to an example of lighting a through-traffic route to show the great difficulties which will have to be surmounted before adequate street lighting can be extended over the whole country.

DOI:10.1049/ji-2.1946.0042

出版商:IEE    

年代:1946

数据来源: IET

摘要:

The failure of turbo-alternator rotors as a result of copper distortion now constitutes a major cause of outage of electrical generating plant and calls for a closer investigation of the causes of such distortion.The authors expand existing theories based on the work-hardening of copper by temperature cycles and give data of the plastic deformation of copper at working temperatures.The results are given of measurements of both temperatures and the stresses in the windings on alternator rotors in service. An analysis of the phenomena causing the stressed condition indicates means for controlling the stresses.The authors describe the modified operating conditions which have been adopted and some of the difficulties arising therefrom, as well as the equipment installed to measure and control the temperature of alternator-rotor windings. A brief reference is made to the economics of the problem.

DOI:10.1049/ji-2.1946.0046

出版商:IEE    

年代:1946

数据来源: IET