摘要:

The paper deals with the flow of current between point electrodes in circular and elliptical areas, a square, a rhombus, narrow and wide lenticular areas and a narrow lune. The flow between points on the surface of metal tubes is considered. Results obtained by the “six points in line” method are quoted. A collection of derived formulae is added.

DOI:10.1049/ji-2.1944.0008

出版商:IEE    

年代:1944

数据来源: IET

摘要:

The problem of boiler plant availability in power stations has become so prominent that a better understanding is essential of the causes of the fouling of heating surfaces by deposits from the products of combustion.Earlier theories based on fused ash particles, sodium sulphate bond or high dew-points have not satisfactorily accounted for various wellestablished facts of observation. The latter include the existence of a period of apparent immunity from deposits in a new boiler plant, the characteristic behaviour of the dust from pulverized fuel firing and the peculiar scale-like form of certain hard deposits occurring on economizer and boiler tubes.The authors, restricting their observations largely to economizers, have found that hard bonded deposits result from certain chemical reactions between flue dust and sulphuric acid. The type of reaction depends on the temperature of the metal parts associated with the deposits.A clear understanding of the reactions involved in the formation of these deposits indicates methods for removing them.The authors offer practical suggestions for the prevention of hard bonded scale formation in economizers. Various types of coal ash are discussed, and characteristics favouring bonded deposit formation are pointed out. The influence of the authors' proposals on plant design is considered.

DOI:10.1049/ji-2.1944.0009

出版商:IEE    

年代:1944

数据来源: IET

DOI:10.1049/ji-2.1944.0010

出版商:IEE    

年代:1944

数据来源: IET

摘要:

The paper describes a design of star-delta starter for squirrelcage motors, the application of which enables this type of machine to be used in many fields where a slip-ring motor has formerly been essential.The investigations which prompted the development of this starter and the subsequent tests and deductions are discussed, with particular reference to centrifugal and similar forms of pumps.

DOI:10.1049/ji-2.1944.0011

出版商:IEE    

年代:1944

数据来源: IET

摘要:

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.

DOI:10.1049/ji-2.1944.0012

出版商:IEE    

年代:1944

数据来源: IET

摘要:

In recent years there has been an increasing call for the installation of emergency—sometimes termed “alternative” or “secondary”—lighting systems. These can be provided by candles or nightlights, gas, dry- or wet-battery torches, accumulators, engine-generator sets, alternative independent mains supply, or by a combination of several methods. The amount of emergency lighting may range from an intensity equal to normal down to the minimum considered necessary for safety and continuation of essential services. This paper deals mainly with the use of accumulators for standby purposes, operated either manually or automatically upon failure of the mains supply and capable of supplying loads for varying periods according to the class of installations, which are grouped under five heads.

DOI:10.1049/ji-2.1944.0015

出版商:IEE    

年代:1944

数据来源: IET

摘要:

The paper is in three Sections.Section 1 describes a new method of reducing current-transformer errors, using a compensator which may be either an integral part of the current transformer or a separate unit for use with an existing transformer. The compensator employs normal design principles and does not depend on highly critical conditions such as saturated cores.Very high accuracies are obtained, and standard transformers may be constructed having almost unmeasurably small errors over the whole current range, using the most sensitive testing equipment.In Section 2 a method of testing voltage transformers is described in which the Arnold current-transformer equipment may be adapted for this purpose. The set measures the difference in error between a standard and the test transformer.Section 3 deals with the estimation of the errors of threephase star-to-star voltage transformers at their working burdens, from the results of tests at unity-power-factor burdens. Two methods are given: the first uses the six phase-neutral test results usually provided by manufacturers; the second, in which no three phase calculations are involved, uses the results of 12 special tests if three phases are to be loaded or of 6 tests if only two phases are to be loaded.

DOI:10.1049/ji-2.1944.0016

出版商:IEE    

年代:1944

数据来源: IET

DOI:10.1049/ji-2.1944.0018

出版商:IEE    

年代:1944

数据来源: IET