Mitsubishi Electric FR-A520-0.4K -55K Instruction Manual page 142

( 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).)
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 and
integral time to slightly higher
values and the differential time to
a slightly lower value, and switch
on the start signal.
Is the process
value steady?
No
Adjust parameters.
Set the proportional band and
integral time to slightly higher
values and set the differential time
to a slightly lower value to stabilize
the process value.
END
*When calibration is required, use Pr. 902 to Pr. 905 to calibrate the detector output and set point setting
input in the PU mode during an inverter stop.
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Set the room temperature to 25°C .
xxxxxx
Set Pr. 128 and switch on the X14 signal to enable PID control.
Detector specifications
xxxxxx
When the detector used has the specifications that 0°C is equivalent to
4mA and 50°C to 50mA, the set point of 25°C is 50% because 4mA is
equivalent to 0% and 20mA to 100%.
When the set point setting input (0 to 5V) and detector output (4 to
xxxxxx
20mA) must be calibrated, make the following calibration*.
Set point = 50%
xxxxxx
Since the specifications of terminal 2 are such that 0% is equivalent
to 0V and 100% to 5V, enter 2.5V into terminal 2.
For PU operation, set the set point (0 to 100%) in Pr. 133.
xxxxxx
During operation, set the proportional band and integral time to
slightly higher values and set the differential time to a slightly
lower value. In accordance with the system operation, reduce the
proportional band and integral time and increase the differential time.
Yes
Optimize parameters.
While the process value is steady,
the proportional band and integral
time may be reduced and the
differential time increased
throughout the operation.
129
PARAMETERS