摘要:

The uses of electrolysis, for the surface cleaning and descaling of metals, for improving the resistance of aluminium and its alloys to oxidation and abrasion, and for the polishing of metals, are discussed.Compared with direct-immersion processes, electrolytic cleaning and descaling is often speedier, more efficient and easier to control. In cathodic cleaning, adventitious matter is loosened by the nascent hydrogen evolved on the surface of the work, while the gas itself is a powerful reducing agent. Anodic pickling in acid electrolytes is precise in action and avoids the dangers of hydrogen embrittlement and of over-pickling. Alternate anodic and cathodic procedures offer certain advantages that are leading to their wider adoption.Theory and practice in the anodic oxidation of aluminium are discussed; reference is made to the use of this type of process to facilitate photographic reproduction on the surface of the metal, and to modifications of anodizing technique designed to produce especially hard, wear-resisting films.The principles of electrolytic polishing are explained. Industrial practice in the electrolytic polishing of steel, nickel, copper and aluminium is outlined. A comparison is drawn between electrolytic and mechanical polishing, and some reference is made to the economics of the electrolytic process.

DOI:10.1049/pi-a.1955.0112

出版商:IEE    

年代:1955

数据来源: IET

摘要:

The paper deals with the 600-volt rolling stock designed and built in England to the order of the Toronto Transportation Commission in Canada (since reconstituted as the Toronto Transit Commission), whose new underground electric railway is now in passenger service. The traction equipment is described, together with the arrangements for the collection of power by the trains and its distribution in them. Particular reference is made to the provisions for the safe return of current to the rails. The low-voltage auxiliary equipment is described, and the extensive arrangements for coach heating and ventilation are set out; the electro-pneumatic braking system and door control are also detailed. The descriptions are preceded by a survey of the traffic problems of the city of Toronto and the decisions taken to expedite the movement of its urban passengers. The paper closes with a few comparisons with similar stock elsewhere and gives numerical data in an appendix.

DOI:10.1049/pi-a.1955.0113

出版商:IEE    

年代:1955

数据来源: IET

摘要:

The aim of the authors is to review the general position with regard to the standardization of retail electricity tariffs in those parts of Great Britain served by the fourteen Area Boards.Broadly, the paper covers:(a) The situation at vesting date (1st April, 1948).(b) How tariff standardization has been tackled.(c) The progress so far made in the introduction of standard tariffs.(d) Problems encountered in introducing standard tariffs.Tariffs for domestic, industrial, commercial and farm consumers and for combined premises are considered. Notes are included on tariffs in the North of Scotland and Northern Ireland, and brief references are made to salient points of comparable tariffs in some other European countries.

DOI:10.1049/pi-a.1955.0119

出版商:IEE    

年代:1955

数据来源: IET

摘要:

The merit of a proposed non-destructive method of assessing the breakdown voltage of stator-coil insulation by means of high-voltage direct current is examined. The proposal is to measure the steady-state leakage current at successive increments of applied voltage and predict a breakdown value from the trend of the plotted results.Laboratory tests applied to a range of specimens of sheet insulation, including a number with artificially-formed faults, indicate that the only breakdown which can be predicted by this method is that across air paths external to the specimen.Tests carried out on a complete high-voltage stator winding and on single stator coils give similar results. No assessment of slot-insulation quality is possible: the only increase in current, suggestive of approaching failure, results from end-winding leakage and discharge effects. Surface contamination of the end-winding and even quite extraneous discharges, when present, have a marked influence on the current measurements.It is concluded that the high-voltage d.c. method of testing investigated has no valid basis for non-destructively indicating the service-ability of the insulation of high-voltage machines.

DOI:10.1049/pi-a.1955.0123

出版商:IEE    

年代:1955

数据来源: IET

摘要:

The behaviour of current transformers in parallel, and of similar circuits employing summation transformers, is studied for different conditions of load distribution.After the existing theory concerning idle currents has been rejected it is demonstrated that the overall error is very nearly constant for a given total load, no matter how the current may be shared among the line transformers. A complete equipment may thus be regarded as a single current transformer and the circuit parameters are considerably simplified, enabling practical formulae to be established for determining the overall errors.In the latter part of the paper it is shown how the effective burdens on the individual transformers may be estimated and how test results at these burdens may be used to compute the overall errors. Worked examples are given, together with confirming test results.

DOI:10.1049/pi-a.1955.0125

出版商:IEE    

年代:1955

数据来源: IET

摘要:

Methods are described for representing synchronous machines, by means of which an a.c. network analyser can be constructed to solve both steady-state and transient power-system problems automatically, without the need for tedious step-by-step processes. An existing a.c. network analyser may readily be converted to dynamic operation by modification of the generator units only, as herein lies the only radical alteration in representation proposed. Choice of time scale for the study of electro-mechanical transients is arbitrary. However, advantages are indicated for a time scale of the order of 1 min on the analyser corresponding to 1 sec on the actual power system. Results of tests (employing a.c. network analyser units) are included, and possible improvements are discussed.

DOI:10.1049/pi-a.1955.0131

出版商:IEE    

年代:1955

数据来源: IET

摘要:

The method of constructing complete capability diagrams for alternators is presented. The various limits of operation, namely rotor and stator heating, stator-end heating and steady-state stability are considered both for a salient pole and for the special case of a round-rotor machine. Methods are given to enable the diagrams to be drawn for various terminal voltages and also for the case of a generator plus unit transformer.

DOI:10.1049/pi-a.1955.0133

出版商:IEE    

年代:1955

数据来源: IET

摘要:

The paper deals with a recent design of mechanical contact rectifier, rated at 15 kA and 220–270 volts, which has been developed in this country. Its constructional features and the reasons for adopting the arrangements selected are described in detail, and a brief account is given of the results obtained. The overall efficiency is over 97%.

DOI:10.1049/pi-a.1955.0139

出版商:IEE    

年代:1955

数据来源: IET

DOI:10.1049/pi-a.1955.0141

出版商:IEE    

年代:1955

数据来源: IET

DOI:10.1049/pi-a.1955.0142

出版商:IEE    

年代:1955

数据来源: IET