| 摘要 |
971,788. Measuring electrically; voltage and current measurement. LEEDS & NORTHRUP CO. March 26, 1962 [April 10,1961], No. 11449/62. Headings G1N and G1U. In a modification, Fig. 4, of the transducer described in Specification 971,787 in which linear displacement of permanent magnet probe 31a from a reference position produces a net D.C. flux in a magnetic circuit comprising a ring core 11 of low loss magnetic material such as a ferrite and two poles 13, 14, preferably of metal, extending perpendicular to the plane of the ring, so that variation of the reluctance of the magnetic circuit due to periodic saturation of the ring core 11 produces changes in the level of D.C. flux which induce an A.C. signal in an output winding 17, the output winding 17 encircles the ring core 11 in such a way that it is in substantially zero-coupling relation with a saturating winding 12, Fig. 5, on the ring core 11. The saturating winding 12 is symmetrically disposed on opposite sides of the ring core 11, and the output winding 17 is supported on a preferably insulating rectangular former 63 and is provided with electrostatic shielding 62. To compensate for any lack of symmetry, a resistor 3, Fig. 1 is shunted across one half of the saturating winding 12. Bosses 11a located on ring core 11 at the positions of contact with poles 13, 14 provide increased mechanical strength and minimise the passage of stray flux from the ring into the poles. Fig. 1 depicts the modified transducer connected in a voltage recording arrangement. An unknown D.C. voltage E, is converted to A.C. by a vibrator 41, amplified at 43, and supplied to the control winding of a 2-phase motor 44 which operates to position the pen and index 46a of a recorder 46 and also to displace permanent magnet probe 31 between limits imposed by stops 34. The feedback current to windings 23a . . . 23d is dropped across a resistor 24 in opposition to E x , and when equilibrium is reached the position of pen and index 46a indicates the strength of E,. Potentiometer 16 in the feedback circuit is adjusted to determine the span of the arrangement, and a temperature sensitive resistor 15, shunted across potentiometer 16, compensates for variations of temperature. |
