Library of Function Blocks
4.53
EXAMPLE 1:
A turbine measures flow rates of up to 6 m
3
/min with a maximum frequency of 600 Hz. The 4-20 mA
signal from the density meter corresponds to a density variation of 0.1 to 1.1 g/m
3
. The counter
increment shall be 1 count for every 1m
3
.
q
v
= 6 m
3
/min = 0,1 m
3
/s f = 600 Hz
3
pulses/m 6000
1.0
600
=−FTR
0.0001666
600
1.0
=−FSV
It is more convenient to use FTR, because FSV is a periodic decimal. Configuration is as follows:
AFTR=6000
AFSV=1
AFE= 1
AMFL=0.1
AZDN=0.1
AMDN=1.1
APLS=32
CTYP=2
CMFR=1
EXAMPLE 2:
An important application of this block is the ratio control of two flow rates or even the control of a
single flow rate. It is possible to obtain a more precise control if the Setpoint is in pulse frequency
and if it is connected to input
B. Using the same block of example 1, the following configuration may
be used:
6B
A
A
A
X
B
B
8A
B
39
40
83
225
151
K01 = 50
BLK118
LOOP G
47
A/M
035
PID
039
ARTH
051
P/DI
071
TOT
067
L/R
031
CO
009
CONTROLLED FLOW
RATE TURBINE METER
BLK = 067
ATU = 0,001
AMFL = 0,1
BLK 051
G - ADJUSTABLE GAIN
BIAS = 0
BIAS = 1
BIAS = 1
G = 0
1
1
2
2
3
94
67
D
E
Fig 4.19.1 - Ratio Control
To Next Page
Loading...
