[DB600] General Instruction Manual MODE 6
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5-8-5
PID dead band/output dead band
For the case of PID control, disturbance of control by steady noise is reduced when the deviation
(difference between PV and SV) is small.
If a set dead band is too large, a residual deviation (offset) may occur more frequently.
For the case of two-position control, there are only two status outputs available: ON and OFF. Therefore,
setting a small value for the dead band causes the ON/OFF output to be repeated and shortens the relay
life.
5-8-6
Control action
There are two types of control action: heating control (Reverse) and cooling control (Direct).
The heating control operation decreases the output value [%] when the measured value (PV) is smaller than
the setting value (SV) (large deviation).
The cooling control operation increases the output value [%] when the measured value (PV) is larger than the
setting value (SV) (small deviation).
5-8-7
Output variation limiter
This function is used to prevent rapid variation in output. It is useful in preventing the control target or
operating part from being exposed to rapid variation. The output variation (in rising/falling) is limited at
every control calculation interval (approx. 0.1 seconds).
For example, when an output variation of 50% is obtained by the control calculation while the output
variation limiter is set to 5%, the time required to reach the 50% variation is: approx. 0.1 seconds x 50 / 5 =
approx. 1.0 second.
This function is disabled in manual output (including the state immediately after switching from MANUAL
to AUTO) and PV abnormal output.
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