摘要:

The paper deals only with the supply, of power for the auxiliaries of a modern power station, no attempt being made to discuss the relative merits of apparatus such as evaporators, ejectors, etc.The following aspects of the problem are dealt with :—(1) Consideration of the different types of auxiliaries used in a station.(2) Consideration of the different types of supplies available.(3) Suitability of different auxiliaries and supplies for various conditions of station working.Seven alternative schemes for the supply to the auxiliaries of a proposed new station are described and tabulated, and the advantages and disadvantages of each are considered in turn.Certain of these are recommended by the authors, this recommendation being based on the principle that no expense should be spared to secure a simple and reliable system of station auxiliaries.Some observations are made on features to be taken care of when auxiliary supplies are being laid down.

DOI:10.1049/jiee-1.1923.0105

出版商:IEE    

年代:1923

数据来源: IET

摘要:

This paper deals with a particular form of regenerative braking for d.c. trains, effected by the application of a differential compound field excitation to the traction motors Speed/torque and speed/current curves are derived mathematically and experimentally, and are compared. A peculiar property of the speed/torque characteristic is a pronounced maximum value, to ignore which might be very serious.

DOI:10.1049/jiee-1.1923.0109

出版商:IEE    

年代:1923

数据来源: IET

摘要:

This instrument consists essentially of an iron drum with an annular recess, in which are situated one or more coils of wire, the ends being connected to pairs of corresponding slip-rings. The drum is mounted on ball bearings, and its periphery, which is shod with cast-iron rings, is machined to run true to 0.0001 in. A small iron or steel shoe fits accurately the curvature of the rings. When a current passes through the coil the drum is magnetized, and this causes the shoe to be pressed on the rings with considerable force. Thus, if the drum is revolved, a pull is required to cause the shoe to slide relatively to the rings. The magnitude of the tangential pull thus obtained is many times greater than that calculated from the product of pressure due to magnetic attraction, using the formulaB2A/8π, and an assumed coefficient of friction μ = ⅓. Subsequent experiments show, however, that the value of fi is about 0.6. The ratio of experimental pull to calculated pull (takingμas 0.6) depends on the flux density at the shoe contact, and may exceed 50. Thus the operation of the device appears to depend on some form of cohesive action incited by magnetism. The present paper deals with this phenomenon, but more particularly, with its application to electric relays, siphon recorders for line and radio-telegraphy, and transmitting keys for radio-telegraphy. The electric circuits for single-current, double-current and valve-circuit working are described in detail.

DOI:10.1049/jiee-1.1923.0119

出版商:IEE    

年代:1923

数据来源: IET

摘要:

This paper consists of an investigation of the proportions and the arrangement of the winding of high-frequency inductances in order to obtain the minimum ratio ofR/L. Both stranded and solid wire coils are dealt with, and the unavoidable limitations arising from the space factor are considered. Results and tables are given which enable simple comparisons to be made between stranded and solid wire coils having either single- or multiple-layer windings.

DOI:10.1049/jiee-1.1923.0121

出版商:IEE    

年代:1923

数据来源: IET