摘要:

The authors begin by pointing out, with the help of a mechanical analogy, the true place which the alternating current transformer takes in the group of plant considered to-day to be standard for the generation, transmission and distribution of electric power on a large scale.They propose the use of high-voltage alternators and the partial abolition of transmforers. In support of these proposals, the authors discuss the gradual growth of conditions favourable to the introduction of the high-voltage alternator, and describe the obstacles in the way of further development at lower voltages.This discussion leads naturally to the advantages to modern alternator design to be derived from the acceptance of the principle of direct generation at high voltages.This discussion leads naturally to the advantages to modern alternator design to be derived from the acceptance of the principle of direct generation at high voltages.Apart from the design of the alternator itself, including its cable leads, there are many ways in which the adoption of such an alternator would effect financila economy in capital outlay and running expenses, and these matters the authors proceed to set out.They then taken a brief survey of what has already been done in the past in the field of direct generation at 30000 volts, and describe in detail a 33000-volt, 25000-kW, 3000-r.p.m. alternator of unique design, built for the North Metropolitan Electric Power Supply Co., for installation in the new power station at Brimsdown, North London. The operating experiences on site since the setting to work of the alternator in August 1928 are stated.As a matter of interst to those engineers and designers engaged in alternator construction and development, and outline is given of some of the experimental research carried out by the authors in the working out of the practical details of the new design, and of the tests made at works on the completed alternator.The paper concludes with some reference to the future possibilities of the extended use of direct generation at high voltages, and the authors ask for a candid expression of opinion from their critics.

DOI:10.1049/jiee-1.1929.0123

出版商:IEE    

年代:1929

数据来源: IET

摘要:

The subject of ventilation is first dealt with, the different systems used in the past, and recent developments, being reviewed. Radial, axial, radial-axial and multiple-inlet systems are referred to, and internal and external fans are discussed.The elimination of eddy currents is next considered, the various methods, past and present, being reviewed. These include: Twisted and transposed windings; twisted and transposed slot conductors; twisting and transposition of end-connections; combination of transposed slot conductors and end-connections.The paper then deals with the magnetic field of stator endconnections and discusses the following matters: Local heating produced in end of core, stator end-plate and stator endconnections; measurements by exploring coils under different load conditions, i.e. leading load, lagging load and shortcircuit; effect of squirrel cage located between stator winding and rotor coil-retaining rings of single-phase generator; neutralization of end field by copper screening plate.In the next section the subject of insulation is treated, the following being considered: Vibration of conductors; swelling of insulation; smooth core design; expansion and contraction of armature conductors; crinkling of insulation; bakelized conductors; clamping of stator winding.Rotor forgings are discussed, especially in connection with the relative advantages of oil-quenching and annealing.Finally, the subject of coil-retaining rings is dealt with, and the method of support, difficulties due to rigidly supported rings, and non-magnetic rings are discussed.

DOI:10.1049/jiee-1.1929.0124

出版商:IEE    

年代:1929

数据来源: IET

摘要:

An investigation of the performance of a small condenser transmitter under different conditions of test is described in Part 1. The results are reduced to terms of the augmentation of the sound pressures at the surface of the transmitter, considered as an obstacle in a sound field; and a comparison is made with the calculated pressures developed on a spherical obstacle.In Part 2, which is of the nature of an Appendix, the accuracies of the methods of measurement are discussed

DOI:10.1049/jiee-1.1929.0130

出版商:IEE    

年代:1929

数据来源: IET

摘要:

The paper deals with the determination by a sensitive electrostatic method of the ratios and phase angles of voltage transformers. The method is described and the theory given, including small corrections which arise in its use. A comparison of this method with another of similar sensitivity, of which a short description is included, indicates that no serious systematic errors are present

DOI:10.1049/jiee-1.1929.0131

出版商:IEE    

年代:1929

数据来源: IET

摘要:

In this paper an accumulation of experimental and statistical data which have been obtained by the author has been brought under review for the purpose of discussing the leading problem in the sphere of meter maintenance, namely that of worn bearings.Attention is drawn to the necessity for improving the reliability of meters in service in consequence of the vast number to be dealt with under modern conditions. The period of sustained accuracy needs to be extended in order to reduce the work of periodically exchanging meters, which is becoming increasingly difficult to contend with.It is submitted that the solution lies in increasing the durability of the bearings and particularly the combination of bottom jewel and pivot which constitutes the footstep bearing.The subject is dealt with in five main sections, which are outlined in the following:In Section (1) typical bearings to be found in electricity meters are illustrated and described and the principal features of design are pointed out. Reference is also made to methods of examining the condition of bearing jewels.Section (2) is directed to a study of the movements of the pivots of meters under load which contribute to the wearing of the bearings. Included in this section is an explanation of the method devised by the author for compensating for fluid friction in mercury motor meters, in which the upward movement is put to practical advantage. The vibratory movements of the rotors of a.c. meters produced by the action of the voltage and current fluxes are dealt with, and the differences observed in the amount of vibration exhibited by different designs are commented upon.In Section (3) the condition in which bearings are found after the meters have been removed from service is discussed. The frequency of the occurrence of defects in the bottom jewel is pointed out and the variety of forms which they take, as revealed by the microscope, is described. Examples of long-life jewels are given and the difficulty of drawing any conclusion as to the cause of wear from the contradictory evidence of life statistics of jewels is pointed out. The extreme obscurity of the problem is recognized, but the author suggests some possible explanations and certain lines along which laboratory research might prove fruitful.Section (4) deals with a special application of the diamond cupped bearing in connection with h.t. polyphase meters working under low-load conditions in exceptional circumstances. Extensive experiments with agate pivots working in sapphire cups are described.In Section (5) the author endeavours to formulate some opinions on various aspects of the bearing question, based on the experience and investigations set out in the paper.

DOI:10.1049/jiee-1.1929.0132

出版商:IEE    

年代:1929

数据来源: IET