GB977746A - Improvements in and relating to methods and systems for measuring phase displacement between two alternating voltages - Google Patents

Abstract

977,746. Phase discriminators. ELECTRICITE DE FRANCE. May 11, 1962 [June 14, 1961], No. 18302/62. Heading H3A. Voltages V 1 , V 2 are applied to Schmitt trigger circuits C 1 , C 2 whereby square waveform signals w 1 , w 2 are produced and converted to pulses d 1 , d 2 by differentiators D 1 , D 2 . Pulse generators R 1 , R 2 receive the pulses d 1 , d 2 and produce corresponding sawtooth pulses u 1 , u 2 . An addition amplifier AA receives the pulses u 1 directly and the pulses u 2 by way of polarity inverter A 1 whereby a voltage is delivered equal to the difference between the pulses u 1 , u 2 . During periods of time a (Fig. 2), the difference between the pulses u 1 , u 2 , namely the output voltage S, is proportional to the phase difference between the voltages V 1 , V 2 . The output voltage S is sustained during intervals of time b (the phase difference between the voltages V 1 , V 2 ), by the addition of negative square pulses u 3 having an amplitude equal to the difference between the pulses u 1 , u 2 , the pulses u 3 being equal in duration to and coincident with the intervals b. The pulses u 3 are produced by a bistable multivibrator circuit B triggered by pulses u 1 , u 2 , a potential divider B 13 being included in its output to enable the amplitudes of the pulses u 3 to be adjusted. The discriminator may include differentiator circuits A 20 , A 30 and amplifiers A 2 , A 3 whereby voltages S<SP>1</SP>, S<SP>11</SP> are produced proportional to the first and second derivatives of the voltage S. The pulse generators R 1 , R 2 have the form of relaxation circuits and may comprise a thyratron R 11 , a pentode R 13 and a triode R 14 connected as shown.