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35 CPU MODULE BUILT-IN ANALOG FUNCTION
35.6 Function (PID Control Via Parameter)
Overlap/dead band function
The temperature where the cooling control output starts is shifted; therefore, select which of the control stability or energy
saving is to be prioritized.
In heating-cooling PID control, the temperature process value (PV) significantly changes due to slight heating
or cooling control output when the heat produced by a controlled object and natural cooling are being
balanced. Consequently, excessive output may be performed.
■Overlap
Overlap refers to the temperature area where both heating control and cooling control are performed. In the temperature area
where both heating and cooling outputs overlap, both of the output negate each other, thus the control gain becomes
moderate. Consequently, the change amount in the temperature process value (PV) for the output becomes small, improving
control stability.
When setting an overlapping area, set a negative value in "Overlap/Dead Band Setting".
■Dead band
Dead band refers to the temperature area where neither heating control output nor cooling control output is performed.
When the temperature process value (PV) is stable within this area, output is not performed for the slight change in the
temperature, contributing to energy saving.
When setting a dead band area, set a positive value in "Overlap/Dead Band Setting".
100%
0%
Output value for heating (MVh)
Output value (MV)
Heating
proportional
band (Ph)
Cooling
proportional
band (Pc)
Target value (SV)
Overlap
Output value for cooling (MVc)
Measured value (PV)
100%
0%
Output value for heating
(MVh)
Output value (MV)
Heating
proportional
band (Ph)
Cooling
proportional
band (Pc)
Target value (SV)
Dead Band
Output value for cooling
(MVc)
Measured value (PV)
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