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(10) Calibration 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.
Setting of set point
Input the set point.
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.
Is the set point stable?
Parameter adjustment
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, and the differential time (Pr.
134) to a slightly shorter time.
*
When calibration is required
To perform calibration for detector output and set point input, set calibration parameters Pr. 902 and Pr. 903 (terminal
2), or Pr. 904 and Pr. 905 (terminal 4). However, use Pr. 934 and Pr. 935 instead of Pr. 904 and Pr. 905 when both of C42
(Pr. 934) and C44(Pr. 935)
(For the details of Pr. 902 to Pr. 905, refer to page 162. For the details of Pr. 934 and Pr. 935, refer to page 228.)
Start
Set the room temperature to 25 C.
Set Pr. 128 and turn on the X14 signal to enable PID control.
Detector specifications
When 0 C
on the assumption that 4mA is 0% and 20mA is 100%.
(Converting set point to % is unnecessary when both of C42(Pr.934) and
C44(Pr.935)
Make the following calibration* when the target setting input (0 to 5V) and
Make calibration.
detector output (4 to 20mA, 0 to 100%) must be calibrated.
When setting 50% as the set point with voltage input
In the specification of terminal 2, 0V converts to 0% and 5V to 100%.
Thus, set 2.5V for 50% to terminal 2.
When setting 50% as the set point with parameter
Set "50" to Pr.133.
(When both of C42(Pr.934) and C44(Pr.935) are set other than "9999", set
"25" as the set point (no % conversion) directly to the Pr.133.)
Operation
When the parameter unit is used for operation, input the set point to
Pr. 133.
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 operation, decrease the proportional band (Pr. 129) and
increase the integral time (Pr. 130). For slow response system where a
deadband exists, differential control (Pr. 134) should be turned ON and
increased slowly.
Yes
No
Parameter optimization
While the measured value is stable
throughout the operation status, the
proportional band (Pr. 129) may be
decreased, the integral time (Pr. 130)
decreased, and the differential time
(Pr. 134) increased.
Adjustment end
"9999". Make calibration in the PU mode during an inverter stop.
Special operation and frequency control
4mA and 50 C
20mA are used, the set point 25 C is 50%
"9999".)
4
227

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