摘要:

The paper explains a very simple method of much improving the performance of 2:1 pole-changing induction motors. In spite of the extensive use of such machines for a very long time past, windings of standard type, as described in most advanced textbooks, seem always to have been used. The new winding discussed in the paper has given excellent results on test.

DOI:10.1049/pi-a.1957.0114

出版商:IEE    

年代:1957

数据来源: IET

摘要:

The first half of the paper is concerned with the fundamental differences between linear induction motors and their more conventional rotating counterparts. In particular, the effects of the discontinuities which are necessarily introduced either in the stator (‘short stator’ effects) or in the rotor (‘short rotor’ effects) are discussed theoretically. Such discontinuities are shown to involve transient conditions in a linear motor, even when the machine runs at constant speed. The exploitation of double-sided and tubular stators is also discussed.The second part of the paper deals with practical applications of linear induction motors. It includes a brief account of the development of a linear motor which produces a reciprocating motion of stable amplitude without the necessity for any switching device. The possible applications of this type of motor to the textile industry are examined. The use of linear motors as liquid-metal pumps is examined in the light of the earlier theory, and the final section suggests an unusual outlook on induction-motor design which was inspired by the study of linear motors.

DOI:10.1049/pi-a.1957.0115

出版商:IEE    

年代:1957

数据来源: IET

DOI:10.1049/pi-a.1957.0116

出版商:IEE    

年代:1957

数据来源: IET

摘要:

The paper describes the background and salient features of the 138 kV a.c. submarine cable interconnection linking the lower mainland of British Columbia with Vancouver Island.After a description of the electrical systems of the British Columbia Electric Co., Ltd., serving these areas, the requirements for additional power are formulated and the considerations leading to the adoption of a submarine cable interconnection are discussed. A following Section explains the determination of the cable route by hydrographic surveys, and the influence of physical site conditions on design and installation. The cable interconnection circuits and associated control, communication and protection systems are briefly described.The considerations resulting in the adoption of the pre-impregnated gas-filled type of cable manufactured in continuous lengths up to 15.6 miles, are then discussed, together with the development, design and performance characteristics of the cable and accessories; and the development, design, and installation of the special plant necessary for the manufacture and handling of the cable in continuous lengths are reviewed.The transport and installation of the cables and accessories are described in the following Section, and the methods and reason for landing the shore ends by a special scow are discussed. The paper concludes with a brief note on the field testing, commissioning and operating record of the cables.

DOI:10.1049/pi-a.1957.0118

出版商:IEE    

年代:1957

数据来源: IET

摘要:

The paper is divided into two Sections, the first of which deals with the advantages of series capacitors for voltage control purposes, and suggests the possibility of dispensing with the use of capacitor protective equipment in the case of certain types of distribution line. The second Section describes existing installations in 11kV and 88kV lines.

DOI:10.1049/pi-a.1957.0119

出版商:IEE    

年代:1957

数据来源: IET

DOI:10.1049/pi-a.1957.0121

出版商:IEE    

年代:1957

数据来源: IET

摘要:

The purpose of the work described was to relate the measured voltage and time-constants of the machine to the frequency and step responses. A brief description of the machine is followed by an outline of the methods adopted to measure its constants, and a statement of the technique for measuring the frequency response is followed by the results obtained. The step-response tests are next described and discussed, and finally a direct transform from step-response to frequency response is put forward.

DOI:10.1049/pi-a.1957.0123

出版商:IEE    

年代:1957

数据来源: IET

摘要:

The fact that an arc moves in the magnetic field of the current flowing in the electrodes towards the arc roots is often used to control its position or to help to bring about its extinction.The paper describes tests made to investigate the factors which affect the movement of an arc between parallel electrodes, fed with current at one end, in air at atmospheric pressure. Some of this movement is quite random and could never be predicted, but much of it—particularly that of the cathode spot—is consistent and regular. The way in which this regular movement of d.c. and a.c. arcs varies with cathode material and electrode spacing has been investigated at currents up to 3000amp a.c. and 500amp d.c.The results show that arc movement cannot be calculated by considering the arc as a physical conductor acted upon by electromagnetic driving forces and aerodynamic retarding forces. The movement is primarily a process of transfer of electron emission along the cathode surface, and is therefore concerned with electrode surface phenomena as well as with movement of the arc in the air between the electrodes.

DOI:10.1049/pi-a.1957.0126

出版商:IEE    

年代:1957

数据来源: IET