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CHAPTER 6 - DETAILED PARAMETER DESCRIPTION
Range
[Factory Setting]
Parameter
Unit
Description / Notes
Select according to the process
Motor Speed
Increase
Fault
Positive
Negative
Select
Direct
Reverse
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.
Table 6.68
- PID action selection
P528
0 to 9999
Process Variable
[ 1000 ]
Scale Factor
1
P529
0 to 3
Decimal Point of
[ 1 ]
Process Variable
-
P528 and P529 define the way the Process variable (P040) will be shown.
P529 defines how many digits are indicated after the decimal point.
P528 must be set according to the equation below:
P528 =
F. S. V. Indication Process x (10)
P529
Gain (AI2 or AI3)
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)
P528 =
25 x (10)
0
= 25
1.000
