GB702462A - Improvements in and relating to x-ray apparatus - Google Patents

Abstract

702,462. Supply systems for space discharge apparatus. PHILIPS ELECTRICAL INDUSTRIES, Ltd. Nov. 28, 1951 [Nov. 28, 1950], No. 29079/50. Class 38 (4) To save heavy cabling and to prevent instantaneous peak loads on the supply system, the high tension supply to an X-ray tube 25, which tube takes a heavy current for a short period of time, is obtained from a generator 3 driven by a relatively small motor 1 capable of driving the generator up to its operating speed but not maintaining it thereat when under continuous load, so that the kinetic energy of the motor-generator system provides at least part of the load. As shown, the generator 3 comprises an H.F. alternator the field 6 of which is controlled by a stabilizer 4 to provide substantially constant output voltage to a variable voltage auto-transformer 7 which feeds, through an isolating switch 10, 10<SP>1</SP> and an H.T. transformer 14, a bridge-connected rectifier 18 ... 21 of which the output is connected across the X-ray tube 25. Following closure of an isolating switch 2, 2<SP>1</SP>, and when the alternator has attained its operating speed and the transformer is correctly adjusted, as may be indicated by a voltmeter 9,- a frequency meter or a tachometer, an exposure may be effected by closure of a switch 13 which causes a time switch, which may be as disclosed in Specification 568,185, to close by means of a solenoid 12 the isolating switch 10, 10' for a predetermined exposure period. The Figure shows a circuit for automatically initiating an exposure on attainment of correct alternator speed, and which comprises the frequency responsive series resonant circuit for a capacitor 27, an inductor 28 and a variable resistor 29 in series with a rectifier bridge 30 across the alternator output. The rectifier 30 feeds the input winding 31 of a magnetic amplifier 32 where output windings 33, 34 control the supply 37 to a time switch control solenoid 36 to close switch 13 when the series circuit resonates at full alternator speed. The motor 1, which may be D.C., or a squirrelcage or capacitor type A.C., may be disconnected as the load is switched on. A constant voltage transformer 26 may feed the X-ray tube filament. Specifications 13854/08, [Class 38], 16853/13, [Class 39 (i)], and 111,570, [Class 38 (iv)], are referred to.