Mitsubishi Electric FR-A500 Instruction Manual page 150

(5) Parameter setting
Parameter
Setting
Number
10
11
20
128
21
0.1 to 1000%
129
9999
0.1 to 3600 s
130
9999
0 to 100%
131
9999
0 to 100%
132
9999
133 0 to 100%
0.01 to 10.00 s
134
9999
(6) Adjustment procedure
Name
For heating, pressure control, etc. Deviation value
For cooling, etc.
PID action
selection
For heating, pressure control, etc. Set point (terminal 2
For cooling, etc.
If the proportional band is narrow (parameter setting is small), the
manipulated variable varies greatly with a slight change of the process value.
Hence, as the proportional band narrows, the response sensitivity (gain)
PID proportional
improves but the stability deteriorates, e.g. hunting occurs.
band
Gain K = 1/proportional band
No proportional control
Time required for the integral (I) action to provide the same manipulated
variable as that for the proportional (P) action. As the integral time decreases,
PID integral time
the set point is reached earlier but hunting occurs more easily.
No integral control.
Set the upper limit. If the feedback value exceeds the setting, the FUP signal
is output. (Process value of 4mA is equivalent to 0% and 20mA to 100%.)
Upper limit
No function
Set the lower limit. (If the process value falls below the setting range, an
alarm can be output. In this case, the process value of 4mA is equivalent to
Lower limit
0% and 20mA to 100%.)
No function
Only valid for the PU command in the PU operation or PU/external combined
PID action set
mode.
point for PU
For external operation, the voltage across 2-5 is the set point.
operation
(Pr. 902 value is equivalent to 0% and Pr. 903 value to 100%.)
Time only required for the differential (D) action to provide the same process
value as that for the proportional (P) action. As the differential time increases,
PID differential
greater response is made to a deviation change.
time
No differential control.
Parameter setting
Adjust the PID control parameters, Pr. 128 to Pr. 134.
Set the I/O terminals for PID control.
Terminal setting
(Pr. 180 to Pr. 186, Pr. 190 to Pr. 195)
Pr. 128 = 10, 11, 20, 21
Switch X14 signal on.
Run
141
PARAMETERS
Description
PID reverse
action
signal input(terminal
PID forward
1)
action
PID reverse
action
or Pr. 133), process
value input (terminal
PID forward
4)
action
4