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Special operation
Calibration example
Example
A detector of 4mA at 0°C and 20mA at 50°C is used to adjust the room temperature to 25°C
under PID control. The set point is given to across inverter terminals 2-5 (0 to 5V).
Determination of set point
Determine the set point of what is
desired to be adjusted.
Conversion of set point into %
Calculate the ratio of the set point to
the detector output.
Input a voltage across terminals 2-5
according to the set value %.
Set the proportional band (Pr. 129)
to a slightly larger value, the integral
time (Pr. 130) to a slightly longer
time, and the differential time
(Pr. 134) to "9999" (no function),
and turn on the start signal.
To stabilize the measured value,
change the proportional band
(Pr. 129) to a larger value, the
integral time (Pr. 130) to a slightly
longer time.
Fig. 6-129: Calibration example
6 - 252
Start
Make calibration.
Setting of set point
Operation
Is the set point stable?
No
Parameter adjustment
Adjustment end
Set the room temperature to 25°C
Set Pr. 128 to "20" or "21", to enable PID control.
Detector specifications
When 0 → 4mA and 50 → 20mA are used, the set point 25°C
is 50% on the assumption that 4mA is 0% and 20mA is
100%.
Make the calibration as described in the following section
when the target setting input (0 to 5V) and detector output (4
to 20mA) must be calibrated.
When the set point is 50%
As the terminal 2 specifications are 0% → 0V and 100% → 5V,
input 2.5V to the terminal 2 for the set point of 50%.
When performing operation, first set the proportional band
(Pr. 129) to a slightly larger value, the integral time (Pr. 130)
to a slightly longer time, and the differential time (Pr. 134) to
"9999" (no function), and while looking at the system opera-
tion, decrease the proportional band (Pr. 129) and increase
the integral time (Pr. 130).
Yes
Parameter optimization
While the measured value is stable
throughout the operation status, the
proportional band (Pr. 129) an the inte-
gral time (Pr. 130) may be decreased.
Parameter
I001237E
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