PURPOSE: To obtain an accurate electric-pneumatic positioner by providing the first series circuit and second series circuit to output the output voltage from an variable impedance element to a controller as a pneumatic signal or valve opening degree signal.
CONSTITUTION: Variable impedance elements 26 whose impedance varies according to valve opening degrees and a constant voltage/current controlling circuit 41 are connected to input terminals T1 and T2 of electric-pneumatic positioners 40 in series as the first series circuit 42. In addition, Transistors 43 and magnet units 21 are connected to the input terminals T1 and T2 in series as the second series circuits 44. In the variable impedance elements 26, voltage Vp2 corresponding to impedance is generated. This corresponds to the valve opening degrees and is sent to a controller 30. An accurate electric-pneumatic positioner(electric- pneumatic converter) which is not affected by the change or dispersion of the temperature of the resistor of the magnet unit 21 is thus obtained in simple constitution.
YAMAGUCHI MASAAKI
HAYASHI HIROSHI
NISHIJIMA TSUYOSHI
KUBOTA RYUSAKU
KASAHARA YASUO
MIDORIKAWA MINORU
