| 摘要 |
1,125,676. Photo-electric measurement of high voltage systems. BROWN BOVERI & CO. Ltd. Feb.1, 1967 [Feb.3, 1966], No.4909/67. Headings G1A and G1U. [Also in Division G2| Measured values are transmitted from a region of high potential to a region of low potential by causing the measured value to modulate the position of a mirror which modulates interferometrically a monochromatic light beam emitted from and received at the region of low potential. Light from a gas laser is transmitted by an optical fibre 10 to an interferometer 7 in the vicinity of a high voltage conductor the current wherein is to be measured. The light beam is split by a Koesters prism 19 to provide beams which are reflected by mirrors 16 and 17 on to a fixed mirror 21, which causes the beam to retrace its path. The portion of the output of a transducer measuring the conductor current is picked off by a temperature variable potentiometer, integrated and applied to electrostrictive converters 14, 15 to modulate the position of the mirrors 16, 17 in antiphase to produce a pulsating light intensity in the divider plane 20 of the prism 19. A 90 degree phase plate 23 covers half of the beam to mirror 16, so that the pulsation of two halves of the combined beam are 90 degrees out of phase. These halves are transmitted by optical fibres 11 to photo-detectors 26, 27, Fig.4. The outputs of detectors 26 and 27 are mixed at 30 and 31 with carrier signals in quadrature from an oscillator 28. The carrier components are removed at 32 and 33 and the modulated signals added at 34 to give a signal which is frequency modulated with the measured current signal. This signal is detected by an f. m. demodulator 38 and fed to an indicator 39 or recorder 40. |
