DOI:10.1049/pi-2.1952.0001

出版商:IEE    

年代:1952

数据来源: IET

DOI:10.1049/pi-2.1952.0002

出版商:IEE    

年代:1952

数据来源: IET

DOI:10.1049/pi-2.1952.0003

出版商:IEE    

年代:1952

数据来源: IET

摘要:

The behaviour of a single-phase series-transductor circuit, with a low-impedance signal source, is examined analytically and experimentally for various load conditions; these include a. c. inductiveresistive loads, rectifier-fed inductive-resistive loads, and rectifier-fed loads with capacitance smoothing of the bridge-rectifier output voltage.Account is taken of the finite permeability of the core when considering the circuit sensitivity with self-excitation feedback. The influence of the load on the control-circuit time-constant is also discussed.The unsatisfactory behaviour of transductors with rectifier-fed inductive-resistive loads is explained and methods of effecting an improvement in performance are suggested.

DOI:10.1049/pi-2.1952.0004

出版商:IEE    

年代:1952

数据来源: IET

DOI:10.1049/pi-2.1952.0005

出版商:IEE    

年代:1952

数据来源: IET

摘要:

A method is described for initiating a current discharge through an object, e.g. a spark-gap, which is initially broken down by a separate impulse-voltage generator. The isolation of the current source necessary to enable the impulse voltage to be developed across the object is provided by a chain of spark-gaps; these are arranged to break down subsequently, in succession, and so complete the discharge path for the current source. This arrangement offers a number of advantages over the microsecond switch due to Bellaschi.An analysis of the operation of the initiating circuit is given; this enables the number and settings of the auxiliary gaps to be determined when account is taken of the various factors that affect the electrode voltages. The causes and effects of incorrect operation are considered and means of inhibiting the discharge of the current source under these conditions are described.The method has been used in the production of current pulses for spark-discharge work, in a gap with a breakdown voltage of up to 150 kV. A delay of about 1.0 microsec between breakdown and the start of the current discharge has been obtained with an initiating circuit having five gaps.

DOI:10.1049/pi-2.1952.0008

出版商:IEE    

年代:1952

数据来源: IET

摘要:

The method described has been used to obtain, in a spark-gap, current pulses of up to 500 amp in amplitude and 10 microsec in duration with a fall-time of less than 0.25 microsec. The discharge in anRCcircuit is modified by inductanceto maintain the current in the gap approximately constant for a period of up to about one-half of the unmodified time-constant; the current in the gap is then chopped by a triggered spark-gap, through which the discharge is completed. Non-linear resistance is used to reduce the fall-time to between onehalf and one-third of that obtained with linear resistance.

DOI:10.1049/pi-2.1952.0009

出版商:IEE    

年代:1952

数据来源: IET

摘要:

The transmission of electrical power by overhead systems has involved electrical engineers in yet another branch of engineering, as certain specialists in the structural steelwork industry fabricate the towers which support current-carrying conductors.The initial cost of an electrical scheme embodying an overhead transmission system can be such that a high proportion of outlay is for the transmission of the current, and the deterioration rate of materials used in construction must be kept aslow as possible so that depreciation of capital value and maintenance costs are minimized. Steelwork in an unprotected state, erected in areas where rainfall and atmospheric pollution can be rated even as normal, deteriorates by corrosion quicker than is acceptable.The general method of protecting transmission structures against corrosion is hot-dip galvanizing, detailed examination ofwhich would be of interest only to those engaged in research on the subject. However, a useful working knowledge of the process and the ability to distinguish a good coat from a bad one can be obtained from a reasonably short study.The object of the paper is to give electrical engineers a brief description of the metallurgical construction of a zinc coat, together with some information on its expected life, and to offer a condensed description of the process, certain methods of quality control and to advise on the after-care of the finished product.

DOI:10.1049/pi-2.1952.0011

出版商:IEE    

年代:1952

数据来源: IET

摘要:

The paper deals with the protection of generators, power transformers, feeders and busbars and with the characteristics of protective transformers. The subject-matter has been selected for the following purposes:(a) To raise some controversial issues relating to protective-gear practice in order to promote discussion upon them in the hope that this will lead to more general agreement. Among these issues are over-current and negative-phase-sequence protection of generators, earthing of the neutral point, the use of Post Office pilot wires for protection, the application ofcarrier-distance protection, the duplication and supervision of busbar-zone protection, and the overlapping of current-transformers.(b) To outline some new problems which have arisen.(c) To describe some new developments of importance, such as instantaneous differential protective system for power transformers, high-resistance pilot-wire scheme, a starting scheme for carrier protection and a biased differential system of busbar-zone protection.(d) To examine briefly the performance requirements of protective transformers.

DOI:10.1049/pi-2.1952.0013

出版商:IEE    

年代:1952

数据来源: IET

摘要:

A general theory of phase transformation by means of static pulsating-flux transformers is presented, i.e.mtonphases on ak-limbed transformer,m,n, andkbeing integers greater than unity. This is derived from the requirements of e.m.f. and m.m.f. balance. Except in the so-called 2-phase case, freedom of choice in selecting the winding elements in each phase always exists and it is always possible to produce a phase transformer for any required transformation ratio and phase shift. It is shown that the effective phase-turns are in general complex and that the ratio of voltage transformation is different from that for current transformation, both being complex and having equal and opposite phase-angles. Equality of primary and secondary power factors is thus established.In the examples given, the Scott and Leblanc connections for 2- to 3-phase transformation are shown to be duals. Two 3- to 4-phase connections are worked out in detail, and the symmetrical phasetransformers used with mercury-arc supplies are discussed briefly.

DOI:10.1049/pi-2.1952.0027

出版商:IEE    

年代:1952

数据来源: IET