ELECTRO-MAGNETIC FLOW METER

摘要

PURPOSE:To remove noise components by sampling signals from electrodes during a pause period, exciting period and periods in those periods when electro- magnetic induction noises extinguish and calculating multiplication of a coefficient with four sample values for a specified length of time that are continuous. CONSTITUTION:An exciting coil 1 is excited by the signal 9 of a calculation control unit 7, and electrodes 3a and 3b provided on an insulation lead pipe 2 are connected to buffer amplifiers 4 and 5 and they are connected to a circuit 7 through a differential amplifier 6. The output of the amplifier 6 is sampled by an A/D converter 7a. The sampling is once during the exciting period of the coil 1 and three times during the pause period. Out of the three samplings during the pause period two samplings are taken when electro-magnetic induction noises have vanished. Each sample value is multiplied by a coefficient to effect addition calculation, and it is output as flow rate signal 11. Individual coefficients are set at values that offset respectively commercial frequency noises, electro-chemical direct current noises and electro-magnetic induction noises. With noises removed flow rate signal of extremely quick response can be obtained.