Manual
1 Technical Description
1.5 Functional description of the structure switches
1.5.4 Controller types (S1, S49 to S53)
66
SIPART DR22 6DR2210
C79000-G7476-C154-03
-- Example of a ratio control
+
+
x
1
GAS
Q
G
Q
L
K
G
K
L
x
2
v
x
y
x
d
--
w
c
+
AIR
Figure 1-33
Control diagram ratio control
In a combustion control the air-/gas flow should be in a constant ratio. The command
variable (commanding process variable) is the air flow Q
L
which is preset in the range 0 to
12,000 m
3
/h as a signal 4 to 20 mA. The controlled variable (following process variable)
is the gas flow Q
G
with a measuring range 0 to 3,000 m
3
/h which is also available as a
4 to 20 mA signal. In an ideal combustion the air/gas ratio is
L
«
ideal
=
= 4.
Q
L
Q
G
= L
«
⋅
λ
Q
L
Q
G
The air factor
λ
is then 1 and should be adjustable in the range from 0.75
to 1.25 on the controller.
The ratio factor v (bei xd = 0) is determined partly by the transmission factors K of the trans-
mitter (measuring ranges).
x
1
= Q
G
⋅
K
G
with the values from the example
100 %
3,000 m
3
/h
K
G
=
x
2
= Q
L
⋅
K
L
100 %
12,000 m
3
/h
K
L
=
v =
= Q
G
Q
L
x
1
x
2
⋅
with
Q
G
Q
L
1
L
«
⋅
λ
=
v =
1
L
«
⋅
λ
K
G
K
L
K
G
K
L
⋅
With the values from the example
v = 1
λ
⋅
1
4
100 %
⋅
h
⋅
12,000 m
3
3,000 m
3
⋅
100 %
⋅
h
⋅
gives
v =
1
λ
i.e. the choice of the transmitter ranges has been made so that
K
G
K
L
=
1
L
«
.
Содержание 6DR2210
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Страница 236: ...Manual 6 Ordering data 234 SIPART DR22 6DR2210 C79000 G7476 C154 03 ...
Страница 242: ...Manual 7 Application examples for configuring the controller 240 SIPART DR22 6DR2210 C79000 G7476 C154 03 ...
Страница 260: ...Manual 9 Explanation of abbreviations 258 SIPART DR22 6DR2210 C79000 G7476 C154 03 ...
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