Mitsubishi Electric 800 Series Instruction Manual page 412

 Calibration example
Adjust room temperature to 25°C by PID control using a detector that outputs 4 mA at 0°C and 20 mA at 50°C.)
Start
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.
Make calibration.
Setting of set point
Input a voltage across terminals 2-5
according to the set value %.
Will you perform
PID gain tuning?
No
Operation
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?
No
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.
Adjustment end
*1 When calibration is required
Calibrate detector output and set point input by Pr.125, Pr.902, and Pr.903 (terminal 2) or Pr.126, Pr.904, and Pr.905 (terminal 4). (Refer to
page 328.) When both Pr.934 and Pr.935 are other than "9999", calibrate the detector output and set point input by Pr.934 and Pr.935 (terminal
4). (Refer to page 421.) Make calibration in the PU operation mode during an inverter stop.
*2 For the PID gain tuning, refer to
Set the room temperature to 25°C.
Detector specifications
When 0°C 4 mA and 50°C 20 mA are used, the set point 25°C is 50%
on the assumption that 4 mA is 0% and 20 mA is 100%.
∗1
Make the following calibration when the target setting input (0 to 5 V)
and detector output (4 to 20 mA) must be calibrated.
• To set the set point to 50% using voltage input
The terminal 2 specification is 0 V for 0%, and 5 V for 100%. Thus, to set to 50%, input 2.5 V to the terminal 2.
• To set the set point to 50% using parameters
Set Pr.133 = "50". (If Pr.934 and Pr.935 ≠ "9999", set "25 (no % conversion)" directly in Pr.133.)
Yes
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
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)
may be increased.
page 415.
The proportional band
Operation
(Pr.129), integral time
(Pr.130), and differential
The optimal constants are
time (Pr.134) are
automatically set by PID gain
∗2 automatically set by PID
tuning.
gain tuning.
5.11 (A) Application parameters
3
4
5
5
5
6
7
8
9
10
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5. PARAMETERS