YOKOGAWA UP750, User Manual

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<Toc> <6. Parameters>
6-27
IM 05E01B02-41E
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Tips about Heating/Cooling Control
In heating/cooling control, the controller outputs the result of computation after splitting it
into heating-purpose and cooling-purpose signals. In addition, the controller can perform
PID control or ON/OFF control on the heating and cooling sides separately. When perform-
ing ON/OFF control, set the proportional band to “0”.
The controller splits the result of computation (0 to 100%) into heating-side and cooling-
side signals, as described below.
• 0% to 50% of the computation result is presented as a 0% to 100% cooling-side
output.
• 50% to 100% of the computation result is presented as a 0% to 100% heating-side
output.
PID computation
0% to 100%
Heating/cooling
computation
0% to 50%
Cooling-side
output limiter
Cooling-side MV
output
0% to 100%
Heating-side MV
output
0% to 100%
50% to 100%
Heating-side
output limiter
PV SP
Manual MV output
Communication
Heating/cooling control provides two methods in which either none of the heating- and
cooling-side outputs are presented or both of the heating- and cooling-side outputs are
presented, as shown in the following figures.
0
Dead band
0
Cooling-side
output
Cooling-side
output
Heating-side
output
Heating-side
output
Output (%) Output (%)
Dead band
100(%) 100(%) 50
50
0
0
Value of control output before split into
heating- and cooling-side outputs
Value of control output before split into
heating- and cooling-side outputs
100 100
Precautions in Heating/Cooling Control
• Keep the ratio of the heating-side proportional band (P) to the cooling-side propor-
tional band (Pc) equal to or below 5.
• If neither the heating-side nor the cooling-side is performing ON/OFF control, setting
the integral time (I or Ic) of one side to “0” results in the Integral Time parameters of
both sides being set to “OFF”, irrespective of the integral time setting of the other side.
1st Edition : May 31,2000-00