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2) Types of PI control interfaces
Process quantity input data (frequency) and feedback input data can be combined as follows for the PI con-
trol of the VF-S9:
Process quantity input data (frequency setting) Feedback input data
Setting method Frequency setting mode
(1) Internal potentiometer setting
(2) Panel input setting
(3) Internal preset-speed setting
(4) External analog setting
VIB (DC: 0-10V)
External analog input
(1)II(DC:4 ∼ 20mA)
(2)VIA(DC:0 ∼ 10V)
Note: When PI control is selected ( = "1"), frequency priority selection ( ) is disabled. In this
case, therefore, since II or VIA is reserved for feedback signal input only, frequency setting by switching
to VIB cannot be executed.
3) Setting PI control
Set " " in the extended parameter (PI control).
(1) Set parameters
(acceleration time) and (deceleration time) to their minimum values (0.1
sec).
(2) To limit the output frequency, set parameters
(upper limit frequency) and (lower limit fre-
quency). If process quantities are set from the operation panel, however, the process quantity setting
range will be limited by the settings of
and .
4) Adjusting the PI control gain level
Adjust the PI control gain level according to the process quantities, the feedback signals and the object to be
controlled.
The following parameters are provided for gain adjustment:
Parameter Setting range Default setting
(P-gain) 0.01 ∼ 100.0 0.30
(I-gain) 0.01 ∼ 100.0 0.20
(P-gain adjustment parameter)
This parameter adjusts the proportional gain level during PI control. A correction value proportional to
the particular deviation (the difference between the set frequency and the feedback value) is obtained
by multiplying this deviation by the parameter setting.
A larger P-gain adjustment value gives faster response. Too large an adjustment value, however, re-
sults in an unstable event such as hunting.
Slow response
Process quantity setting value
Time
Fast response