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SELECTING THE PROPORTIONAL AND INTEGRAL CONSTANTS IN THE DIRECT DIGITAL CONTROL OF DISCHARGE AIR TEMPERATURE.

Author(s) : NESLER C. G., STOECKER W. F.

Summary

ONE OF THE STRENGTHS OF DIRECT DIGITAL CONTROL IN HVAC APPLICATIONS IS THAT SUCH FEATURES AS THE INTEGRAL MODE CAN BE INCORPORATED IN SOFTWARE RATHER THAN USING MORE EXPENSIVE HARDWARE. WHEN PROPORTIONAL INTEGRAL CONTROL IS USED, IT IS NECESSARY TO SELECT BOTH THE PROPORTIONAL AND INTEGRAL CONSTANTS IN A COMBINATION THAT PROVIDES RESPONSIVE, YET STABLE, CONTROL. THE AUTHORS REPORT THE BEHAVIOUR OF AN EXPERIMENTAL SYSTEM WITH VARIOUS COMBINATIONS OF THESE 2 CONSTANTS. VALVE AND DAMPER ACTUATORS TYPICALLY EXPERIENCE HYSTERESIS AND THE INTEGRAL MODE WOULD ULTIMATELY COMPENSATE FOR THIS NON-LINEARITY. THIS PROCESS MAKES A STEP CHANGE IN THE CONTROL SIGNAL WHEN THE DIRECTION OF CONTROL ACTION REVERSES.

Details

  • Original title: SELECTING THE PROPORTIONAL AND INTEGRAL CONSTANTS IN THE DIRECT DIGITAL CONTROL OF DISCHARGE AIR TEMPERATURE.
  • Record ID : 1986-0335
  • Languages: English
  • Publication date: 1984
  • Source: Source: ASHRAE Trans.
    vol. 90; n. 2B; 834-845; 9 fig.; 10 ref.; discuss.
  • Document available for consultation in the library of the IIR headquarters only.

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