WEG CFW-09 User Manual page 224

[Factory Setting]
Parameter
P528
Process Variable
Scale Factor
P529
Decimal Point of
Process Variable
Range
Unit Description / Notes
Select according to the process
Process requirement:
PID action type: the PID action should be selected as Direct, when it is
required to increase the motor speed in order to increase the process
variable. Otherwise, select the Reverse.
Example 1 - Direct: pump driven by frequency inverter and filling a tank,
where PID regulates the level. To increase the level (process variable) it
is required to increase the flow and consequently, the motor speed.
Example 2 - Reverse: Fan driven by frequency inverter and cooling a
cooling tower, with PID controlling its temperature. With the temperature
increase the error becomes negative and the speed increases, cooling
down the tower.
P528 and P529 define the way the Process variable (P040) will be shown.
0 to 9999
[ 1000 ]
P529 defines how many digits are indicated after the decimal point.
1
P528 must be set according to the equation below:
0 to 3
[ 1 ]
-
where:
F. S. V. Indication Process is the full scale value of the Process Variable,
corresponding to 10 V (20 mA) at the Analog Input (AI2 or AI3) used as
feedback.
Example 1: (Pressure Transducer 0 to 25 bar - Output 4 to 20 mA)
- Desired indication: 0 to 25 bar (F. S.)
- Feedback Input: AI3
- Gain AI3 = P242 = 1.000
- Signal AI3 = P243 = 1 (4 to 20 mA)
- P529 = 0 (no digit after decimal point)
CHAPTER 6 - DETAILED PARAMETER DESCRIPTION
Motor Speed
Fault
Positive
Increase
Negative
Table 6.68 - PID action selection
F. S. V. Indication Process x (10)
P528 =
Gain (AI2 or AI3)
25 x (10)
P528 =
1.000
Select
Direct
Reverse
P529
0
= 25
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