Analyzing costs of digital and analog control systems. [Petroleum refinery]
L.T. Garrett, John McHenry · OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) · 1981
This paper presents an in-depth analysis of total installed costs for both electronic analog and distributed digital process control instrumentation. The study involved approximately 400 data points and 100 control loops. Electronic analog control instrumentation in this study is assumed to be stand-alone single loop controllers with all associated signal conditioning, analog computing logic and alarm annunciation mounted in racks and panels in a central control center. Any digitizing of signals is performed by input/output hardware associated with a computer, with digitizing performed for use by the computer function. Distributed digital control instrumentation in this study is assumed to consist of field device interface hardware and CRT based operator stations. 4 refs.