摘要:

The object of this paper is to indicate some of the problems which still await satisfactory solution in the application of the automatic rotary-convertor substation to heavy electric traction.The need for overhauling present designs, with a view to decreasing maintenance, is pointed out.The phenomena which occur on short-circuiting a rotary convertor are discussed.The high-speed breaker and its advantages are described, and the difficulty now found in securing accurate calibration is referred to, coupled with a suggestion for overcoming this difficulty by the use of stabilizing resistances.The importance of sufficiently insulating series windings, whether connected on the earthed side of the machine or not, is pointed out.The effect of high ambient temperature on machine output is discussed, with special reference to sets operated through thermal relays, as is the case in automatic substations, and the importance of ventilating the machinery with fresh air from outside the substation is emphasized.The use of air filters, and the type of filter most suitable for the conditions, are discussed.A type of opening which gives free egress for the air and prevents the entrance of rain is described.Suggestions are made regarding the method of ventilating the armature core when forced ventilation is adopted.A vertical design of rotary convertor which seems to offer advantages is described.The present design of thermal relay is discussed and suggestions are made for its modification, so as to imitate more closely the heating which occurs in the rotary-convertor armature under the varying conditions of operation. An alternative method, depending upon the actual hot-spot temperature and eliminating an independent thermal relay, is described.The available means of obtaining control current for the operation of the automatic equipment are considered, particularly from the point of view of the complete or partial elimination of batteries and, if they must be retained, of the most suitable type to employ.Fire risk and the means available for fire quenching in the event of sustained conflagration are discussed.

DOI:10.1049/jiee-1.1928.0069

出版商:IEE    

年代:1928

数据来源: IET

摘要:

Part I of the paper describes the wiring systems at present in favour and comments on the qualities of each, with particular reference to suitability for the safe conveyance of electricity in domestic buildings under new supply conditions.It is argued that a metallically continuous, screwed, steel system with metal boxes at all outlets most nearly fulfils ideal requirements, and that attention should be more particularly directed to the development and improvement of this system and its applications. More concentration on one good system should ultimately simplify rules and regulations, and increased production and more uniform practice must lower initial costs and improve the general quality of work.Part 2 treats more of the arrangements and lay-out of wiring in houses of 10 apartments and less, and gives the author's views on the planning of circuits for lighting and power and for combined load. Some suggestions are offered whereby new building structures might be made more suitable to receive electrical installations. A basis for estimating provisional costs, other than a rate per point, is indicated and it is suggested that the inspection of installations might be undertaken by inspectors responsible only to a joint body of control.

DOI:10.1049/jiee-1.1928.0075

出版商:IEE    

年代:1928

数据来源: IET

摘要:

The applications of electricity in the home are surveyed, and a general review of the subject is presented. The paper is divided into the following sections:-(1) Lighting.(2) Heating.(3) Water heating.(4) Cooking.(5) Refrigeration.(6) Tariffs.(7) Comparative costs of building.(8) Conclusions

DOI:10.1049/jiee-1.1928.0076

出版商:IEE    

年代:1928

数据来源: IET

摘要:

This paper is an examination of the efficiency of the rheostatic speed control of a motor when the load is such that the torque is a definite function of the speed. It is shown that, so long as the torque decreases with speed, the controller losses for a given reduction in speed may be considerably less than in the case of a motor working against a constant load torque; also, the greater the reduction in speed, the greater will be the advantage of rheostatic control in the case of such loads. The case of both direct-current and induction motors is considered, and it is shown that, with the latter motor, the inefficiency due to controller losses may be less important than the lowering of the power factor.

DOI:10.1049/jiee-1.1928.0087

出版商:IEE    

年代:1928

数据来源: IET