WEG CFW-11 Programming Manual page 276

PID Regulator [46]
(a) Direct
P0040
P0041
P0535
(b) Reverse
P0040
P0535
P0041
(c) Sleep Mode
P0002
P0134
P0133
Being:
ed or er the percent deviation to activate the wake-up mode.
3) To define the feedback input: the feedback (process variable measurement) is always done via one of the
analog inputs (selected at P0524). In order to make this guide easier, the AI2 input will be selected (P0524 = 1).
4) To adjust the process variable scale: the transducer (sensor) to be used for the process variable feedback
must have a full scale of at least 1.1 times the highest value to be controlled.
Example: If a 20 bar pressure has to be controlled, a sensor with a full scale of at least 22 bar (1.1 x 20) must
be chosen.
Once the sensor has been defined, the type of signal to be read at the input (if current or voltage) must be
selected and the corresponding switch (S1 or S2) be set for that selection.
In this guide it will be assumed that the sensor signal will be 4 to 20 mA (configuring P0238 = 1 and S1.3 = ON).
Afterwards, the gain (P0237) and the offset (P0239) of the feedback signal can be adjusted so that the process
variable be read at the analog input with the highest possible resolution without saturation. In this case, adjust
the parameters P0237 and P0239, according to the following example.
20
NOTE!
In order to avoid the saturation of the feedback analog input during regulation overshoots, the signal
must range from 0 to 90 % (0 to 9 V / 4 to 18 mA). This adaptation can be done by changing the
gain of the analog input selected as feedback.
20-4
AI2 Process Variable
Set Point
Process Variable
AI2
Set Point
Motor Speed
P0133 < P0291 < P0134
Figure 20.2 - (a) to (c) - PID action type
Direct PID (P0527 = 0)
ed = P0041 - P0040 (%)
Reverse PID (P0527 = 1)
er = P0040 - P0041 (%)
Time for the Sleep
Function
P0219
Sleep Mode
P0217=1
t
t
t
Sleep Mode