| 摘要 |
A valve positioner and current-to-pneumatic converter having a reduced number of components and increased current allocation to a current-to-pneumatic conversion module therein, wherein current signals containing set point information are applied to a digital computation circuit through input terminals which carries out control computation to control valve openings so that each valve opening agrees with each corresponding set point; and a current-to-pneumatic conversion module converts the control outputs from the digital computation circuit into pneumatic signals; and further comprising a power voltage generator that generates an internal power voltage from the current signal; a variable impedance circuit connected in series to the power voltage generator and in parallel to the current-to-pneumatic conversion module; and an impedance control circuit that controls the impedance of the variable impedance circuit. |
