摘要:

The paper discusses the regulations relating to the design and practice of overhead-line construction, with particular reference to the Electricity Commissioners' Overhead Line Regulations. It gives a short history of the Commissioners' Regulations and the author's views on what would constitute a good code of regulations. The author traces the background of the existing regulations and examines the proposed revised code prepared by The Institution's Code of Practice Committee on Overhead Power Lines.The paper has been prepared primarily to elicit criticism of the Committee's proposals, in the hope that such criticism will be helpful when preparing the final draft.Attached to the paper are the present code El.C. 53 (1947 Revise) (Appendix 8.1) and the draft proposals of the Code of Practice Committee (Appendix 8.2).

DOI:10.1049/pi-2.1949.0188

出版商:IEE    

年代:1949

数据来源: IET

摘要:

A new technique is described whereby a recurrent-surge indication of the inherent restriking transient in either dead or live power networks can be obtained. The principle underlying this technique, which may be called a “half-wave injection” method, is explained, and a few illustrative laboratory records are given. The surge produced is of the order of a hundred volts, depending on the magnitude of the system inductance and the current rating of the required rectifier unit.

DOI:10.1049/pi-2.1949.0194

出版商:IEE    

年代:1949

数据来源: IET

摘要:

It is normal to regard the loss in a ferromagnetic material undergoing magnetization as the sum of a hysteresis loss, which might be measured by a ballistic method, and an eddy-current loss, calculable from a knowledge of the shape and resistivity of the material and the flux changes involved. For some sheet steels the measured loss is considerably in excess of this sum, and it is with this discrepancy that the paper is concerned. A pulse method of excitation is used, a constant voltage being applied suddenly to the specimen for times ranging from 0.2 to 2.5 microsec. It has been found that, in most instances,B/Hcurves are either linear or can be closely approximated by functions of the formB=B̂(1−ε−αH) orB=B̂(ε−αH−1), whereB̂and α are constants. By adopting these exponential expressions, accurate calculation of eddy-current losses in the non-linear regions has been made possible. In the paper, several theories of the cause of the discrepancy are suggested and examined in the light of experimental evidence in which the rate of change of mean flux density, the polarizing field, the grain orientation and the lamination thickness are varied. It is concluded that the discrepancy is at least partly caused by a variation of permeability and resistivity across the lamination thickness; but it is also shown that a reduction of the effective permeability, due to the inability of the elementary irreversible changes of magnetization (Barkhausen jumps) to be completed in the time available, could also contribute to a “discrepancy loss” which would vary with the factors above in a manner consistent with the experimental results.

DOI:10.1049/pi-2.1949.0195

出版商:IEE    

年代:1949

数据来源: IET

摘要:

The observed anisotropy of oriented polycrystalline silicon-iron sheet is discussed with reference to the results of crystal physics. It is shown that whilst the material can be regarded as homogeneous, e.g. for elasticity or magnetic torque, good agreement is obtained between theory and experimental results on the oriented sheet. An equivalent model aggregate is described which simulates very closely the observed properties of the sheet.The application of the domain theory of ferromagnetism to the anisotropy of magnetic properties is discussed, and it is suggested that the problems arising might be explained by considering the actual domain configuration of the material. Experimental results on hysteresis loss, permeability, magnetostriction, etc., for oriented sheet are considered in relation to the domain changes taking place during magnetization.The more complex phenomena occurring during alternating-current magnetization are considered in relation to the simpler magnetic properties discussed earlier.

DOI:10.1049/pi-2.1949.0196

出版商:IEE    

年代:1949

数据来源: IET

摘要:

The paper describes research on the excessive wear on bearings of meters caused by parasitic forces existing in the meter. A simple experimental technique has been developed which should be of use to designers, and should lead, when new designs are contemplated, to the production of meters that are free from vibrational wear, and that will, in consequence, have an extended service period. Considerable improvement may be effected in many meters without serious modifications in design.

DOI:10.1049/pi-2.1949.0197

出版商:IEE    

年代:1949

数据来源: IET

摘要:

The paper presents a theory of the stator-fed a.c. commutator machine with fixed brushes and induction regulator to provide the variable voltage and/or phase-shifting effect in the rotor circuit for both shunt and series connection. Circle diagrams are developed using a minimum of mathematical treatment without, however, sacrificing accuracy, whilst a maximum of conclusions useful in practice are drawn. A number of regulator systems of known and recently developed design are also described.

DOI:10.1049/pi-2.1949.0202

出版商:IEE    

年代:1949

数据来源: IET

摘要:

Although the impulse voltage testing of transformers has long been recognized as a necessity, to ensure satisfactory design, there has hitherto been no entirely satisfactory method for detecting the occurrence, during such tests, of insulation failures—particularly of the type which impulse tests are especially liable to produce; namely between sections or between turns of the winding. Attention is drawn to a new fault-detection technique recently proposed in the U.S.A., and a summary is given of published information on this subject from various American and European sources.Details are presented of some exploratory experimental work done by the authors, with a view to ascertaining the usefulness of the new technique, and a brief outline is given of the theoretical principles on which it depends. This is followed by a review of the authors' experiences in the practical application of the new methods to the routine impulse testing of 3-phase power transformers over a period of about 2 years. The various practical difficulties encountered are discussed, and means by which they may be avoided are indicated. Tentative test circuits for various types of 3-phase transformers are proposed.It is concluded that the technique described permits the condition of the transformer after impulse tests to be established with confidence. In the authors' opinion the results obtained merit the introduction of the new technique as a standard procedure in the impulse testing of transformers.

DOI:10.1049/pi-2.1949.0204

出版商:IEE    

年代:1949

数据来源: IET

DOI:10.1049/pi-2.1949.0209

出版商:IEE    

年代:1949

数据来源: IET