Proportional Control - Taie FY400 Operation Manual

11.8 Proportional Control

Description
Proportional control is one of the simplest ways to control method, controller manipulated value proportional to input error signal,
this chapter explains how to set related parameters.
Function Diagram
90
Parameter
Parameter Symbol
SV ---
P1
OUD
Setting step
1. Select control action
2. Determine the proportional band
3. Calculate symmetry value, symmetry value = ( proportional band maximum - proportional band minimum) / 2
4. Set SV, SV = Midpoint of proportional band
5. Full range = (Range maximum – range minimum)
6. Calculate Error% = (symmetry value / Full range) x 100
7. Calculate P = (Error% x 2)
Example 1 :
INP1 = K1(-50.0~600.0) when PV in the range of 90.0 ~ 100.0 output proportional(decrease) SV= ? P= ?
1. OUD = HEAT(Reverse)
2. Proportional band 90.0~100.0
3. Symmetry value = (proportional band maximum - proportional band minimum) / 2  (100.0 - 90.0) / 2 = 5.0
4. SV = Midpoint of proportional band  SV= 95.0
5. Full range = (Range maximum – range minimum)  600.0 - (-50.0) = 650.0
6. Error% = (Symmetry value / Full range) x 100  (5.0 / 650.0) x 100 = 0.76923
7. P= (Error% x 2)  0.76923 x 2 = 1.5384(approx 1.5)
Example 2 :
INP1= AN4(0.0~100.0) when PV in the range of 0.0 ~ 100.0 output proportional(increase)
proportional band 0.0~100.0
Output 0%
0.0
1. OUD = COOL(Direct)
2. Proportional band 0.0~100.0
3. Symmetry value = (proportional band maximum - proportional band minimum) / 2  (100.0 - 0.0) / 2 = 50.0
4. SV = Midpoint of proportional band  SV= 50.0
5. Full range = (Range maximum – range minimum)  100.0 - 0.0 = 100.0
6. Error% = (Symmetry value / Full range) x 100  (50.0 / 100.0) x 100 = 50.0
7. P= (Error% x 2)  50.0 x 2 = 100.0
Notes
1. When using proportional control I1 and D1 must be set to 0
2. Full range please check Chapter 4 "Input Range Table"
3. Only using proportional control will eventually have a steady state error
53
Reverse
80 70 60 50 40 30 20 10 %
Content
Set value
Main output proportional band
0.0 : ON/OFF control
Other values : proportional band
setting value
Control action selection
0 : HEAT reverse action
1 : COOL direct action
90 80 70 60 50 40 30 20 10 %
10 20 30 40 50 60 70 80 90 %
Output 100%
100.0
50.0
Direct
Range
Default
MAX MIN
USPL LSPL
200.0 0.0 3.0
COOL HEAT HEAT
SV= ? P= ?
PV
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Level
Display
--- Level 1
Level 2
Level 3 SET7.2
FY operation manual
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