146
PARAMETERS
(7) 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 (0-5V).)
Yes
No
*When calibration is required, use Pr. 902 and Pr. 903 (terminal 2) or Pr. 904 and Pr. 905 (terminal 4)
to calibrate the detector output and set point setting input.
Perform calibration in the PU mode during an inverter stop.
START
Determine the set point.
Determine the set point of the
item to be adjusted.
Convert the set point into %.
Calculate the ratio of the set
point to the detector output.
Make calibration.
Set the set point.
Enter a voltage to across
terminals 2-5 according to
the set point (%).
Operation
Set the proportional band (Pr.129)
and integral time (Pr. 130) to slightly
higher values and the differential
time (Pr. 134) to "9999" (function
invalid), and switch on the start signal.
Is the process
value steady?
Adjust parameters.
Set the proportional band (Pr. 129)
and integral time (Pr. 130) to slightly
higher values and set the differential
time (Pr.134) to a slightly lower value
to stabilize the process value.
END
Optimize parameters.
While the process value is steady,
the proportional band (Pr. 129) and integral
time may (Pr. 130) be reduced and the
differential time (Pr. 134) increased
throughout the operation.
xxxxxx
Set the room temperature to 25
°
C
Set Pr. 128 and switch on the X14 signal to enable PID control.
xxxxxx
Detector specifications
When the detector used has the specifications that 0
°
C is equivalent to
4mA and 50
°
C to 20mA, the set point of 25
°
C is 50% because 4mA is
equivalent to 0% and 20mA to 100%.
xxxxxx
When the set point setting input (0 to 5V) and detector output (4 to
20mA) must be calibrated, make the following calibration*.
xxxxxxSet point = 50%
Since the specifications of terminal 2 are such that 0% is equivalent
to 0V and 100% to 5V, enter 2.5V into terminal 2.
xxxxxxFor PU operation, set the set point (0 to 100%) in Pr. 133.
During operation, set the proportional band (Pr. 129) and integral time
(Pr. 130) to slightly higher values and set the differential time to "9999"
(function invalid). In accordance with the system operation, reduce the
proportional band and increase integral time (Pr. 130) for the slow
responce system, gradually increase the differential time
(Pr. 134) using differential control.
