摘要:

The paper deals mainly with an inverstigation of the dependence on the exciting peak voltageVand the currentIof the output of a hot-cathode X-ray tube as measured by a “free-air” ionization chamber or by a photographic method. The relation may be expressed in the formOutput ∝IVnIn the case of two types of commercial X-ray tubes (Goolidge and Metalix) when excited by constant voltages ranging from 65 to 150 kV,nis found to increase from unity for unfiltered radiation from a tube with a thin window, to between 4 and 5 or more for heavily filtered radiation. The various types of valve rectification circuits suitable for X-ray work, and the influence of voltage and current waveform, are discussed. It is shown that for like values of peak voltage and milliammeter readings, the X-ray outputs for full-wave and half-wave rectification are the same over the voltage range 40 to 80 kV, while the output for constant voltage is about 1.8 times larger for unfiltered radiation.The various types of value rectification circuits suitable for X-ray work, and the influence of voltage and current waveform, are discussed. It is shown that for like values of peak voltage and milliammeter readings, the X-ray outputs for full-wave and half-wave rectification are the same over the voltage range 40 to 80 kV, while the output for constant voltage is about 1.8 times larger for unfiltered radiation.From an X-ray point of view it is concluded that the essential factors of voltage excitation are the peak value and the wave-form. The several methods of measuring high voltages are dealt with. As regards tube currents, the moving-coil milliammeter customarily employed only indicates the mean current and not the maximum current through an X-ray tube excited by pulsating voltage. It is concluded that while the moving-coil milliammeter is adequate for the measurement of sustained tube currents, it is better to turn to some form of ballistic meter for currents lasting less than about 1 second.

DOI:10.1049/jiee-1.1933.0153

出版商:IEE    

年代:1933

数据来源: IET

摘要:

The paper gives a general account of the electrification of a suburban line operating from Manchester. This is the first passenger line in this country to be electrified on the 1500-volt d.c. overhead system.A short historical introduction precedes a general account with detailed reference to special features of the equipment installed and the reasons governing the type selected. The information is given under sections devoted to substation plant, overhead and track equipment, rolling stock, electrical equipment, and car repair shed.The equipment includes a number of features which have not previously been used in this country. For example: the rectifier is the first to operate at 1500 volts; the remote control of one substation from the other is the first application of the Midworth transmitter to this duty; the pantographs are the first to use the curved pan; the motors are the most powerful of any in use in this country.Particulars are given of the more interesting operating experiences, in particular the behavior of the mercury-arc rectifier, the overhead contact wire, and the rolling stock. The paper concludes with some particulars of energy consumption, and technical particulars of the plant installed are given in an appendix.

DOI:10.1049/jiee-1.1933.0155

出版商:IEE    

年代:1933

数据来源: IET

摘要:

The paper aims at giving a survey of the properties, characteristics, and position, of the electric induction furnace as used for steel-melting. Mathematical considerations are not given full, but sufficient are included to show the extent to which the skin effect is of importance. A 1/4-ton furnace is described, together with some details of the auxiliary apparatus and the usual lay-out in steelworks.The performance of such a furnace is indicated, with typical wattmeter traces of runs; and an attempt is made to show the manner of the energy dissipation, thus affording an insight into the efficiency of induction heating.Finally, some consideration is given to the metallurgical aspect of the furnace, with a description of the Rohn method of making a lining. An extension of the usefulness of the type of melting unit is urged and its potentialities for refining are outlined.

DOI:10.1049/jiee-1.1933.0160

出版商:IEE    

年代:1933

数据来源: IET

摘要:

Geo-electrical methods of prospecting depend on the marked differences in the resistivity which exist between adjacent geological formations, these differences being produced by variations in the porosity of the rocks and in the nature of the saline solutions which they contain. Minerals with a metallic luistre usually have a low resistivity. The variations in resistivity are revealed by the anomalous flow through the ground of an applied current, and the work consists in determining the current flow and interpreting the anomalies in terms of geological structure. The usual methods employed are the surface-potential methods (i.e. the resitivity method, equipotential-line methods, and equiquadrature methods, etc.), and the inductive methods at high or low frequencies, in which the current distribution is examined by means of the magnetic field associatedc with it. The methods may be applied to the location of good conducting ore bodies, faults, and dykes, to the measurement of depths, and also for the plotting of subsurface contours. Under favourable circumstances sulphide bodies may be detected by the natural currents which they produce(spontandeous-polarization method).

DOI:10.1049/jiee-1.1933.0162

出版商:IEE    

年代:1933

数据来源: IET

DOI:10.1049/jiee-1.1933.0164

出版商:IEE    

年代:1933

数据来源: IET