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Special operation and frequency control
4
PARAMETERS
4.21 Special operation and frequency control
4.21.1 PID control (Pr. 127 to Pr. 134, Pr. 241, Pr. 553, Pr. 554, Pr. 575 to Pr. 577,
C42 (Pr. 934) to C45 (Pr. 935))
Purpose Parameter that must be Set
Refer
to Page
Perform process control such as pump and air
volume.
PID control
Pr. 127 to Pr. 134, Pr. 241,
Pr. 553, Pr. 554,
Pr. 575 to Pr. 577,
C42 (Pr. 934) to C45 (Pr. 935)
261
Switch between the inverter operation and
bypass operation to operate.
Bypass-inverter switchover
function
Pr. 135 to Pr. 139, Pr. 159 274
Avoid overvoltage alarm due to regeneration by
automatic adjustment of output frequency.
Regeneration avoidance
function
Pr.665, Pr. 882 to Pr. 886 279
The inverter can be used to exercise process control, e.g. flow rate, air volume or pressure.
The terminal 2 input signal or parameter setting is used as a set point and the terminal 4 input signal used as a
feedback value to constitute a feedback system for PID control.
Parameter
Number
Name
Initial
Value
Setting
Range
Description
127
PID control automatic
switchover frequency
9999
0 to 400Hz
Set the frequency at which the control is automatically
changed to PID control.
9999 Without PID automatic switchover function
128 PID action selection 10
10, 110
*2 PID reverse action
Deviation value signal input
(terminal 1
*4)
11, 111
*2 PID forward action
20, 120
*2 PID reverse action
Measured value (terminal 4
*5)
Set point (terminal 2
*4 or Pr. 133)
21, 121
*2 PID forward action
50
*2 PID reverse action
Deviation value signal input
(L
ON
W
ORKS
, CC-Link communication)
51 *2 PID forward action
60
*2 PID reverse action
Measured value, set point input
(L
ON
W
ORKS
, CC-Link communication)
61 *2 PID forward action
129
*1 PID proportional band 100%
0.1 to 1000%
If the proportional band is narrow (parameter setting is small),
the manipulated variable varies greatly with a slight change of
the measured value. Hence, as the proportional band narrows,
the response sensitivity (gain) improves but the stability
deteriorates, e.g. hunting occurs.
Gain Kp = 1/proportional band
9999 No proportional control
130
*1 PID integral time 1s
0.1 to 3600s
When deviation step is input, time (Ti) is the time required for
integral (I) action to provide the same manipulated variable as
proportional (P) action.
As the integral time decreases, the set point is reached earlier
but hunting occurs more easily.
9999 No integral control.
131 PID upper limit 9999
0 to 100%
*3
Set the upper limit value. If the feedback value exceeds the
setting, the FUP signal is output. The maximum input (20mA/
5V/10V) of the measured value (terminal 4) is equivalent to
100%.
9999 No function
132 PID lower limit 9999
0 to 100%
*3
Set the lower limit value. If the measured value falls below the
setting range, the FDN signal is output. The maximum input
(20mA/5V/10V) of the measured value (terminal 4) is
equivalent to 100%.
9999 No function
133
*1 PID action set point 9999
0 to 100%
*3 Used to set the set point for PID control.
9999 Terminal 2 input is the set point.
134 *1 PID differential time 9999
0.01 to
10.00s
When deviation lamp is input, time (Td) is the time required to
provide the manipulated variable of only the proportional (P)
action. As the differential time increases, greater response is
made to a deviation change.
9999 No differential control.