Danfoss VLT HVAC Drive FC 100 Series, Руководство по конструкции

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Figure 2.7 When using a Adjustable frequency drive to reduce
fan capacity to 60% - more than 50% energy savings may be
obtained in typical applications.
2.7.3 Example of Energy Savings
As can be seen from the figure (the laws of propor-
tionality), the flow is controlled by changing the RPM. By
reducing the rated speed by only 20%, the flow is also
reduced by 20%. This is because the flow is directly
proportional to the RPM. The consumption of electricity,
however, is reduced by 50%.
If the system in question only needs to be able to supply a
flow corresponding to 100% a few days each year, while
the average is below 80% of the rated flow for the
remainder of the year, the amount of energy saved is even
greater than 50%.
The laws of proportionality
Figure 2.8 describes the dependence of flow, pressure and power
consumption on RPM.
Q = Flow
P = Power
Q
1
= Rated flow P
1
= Rated power
Q
2
= Reduced flow P
2
= Reduced power
H = Pressure n = Speed regulation
H
1
= Rated pressure n
1
= Rated speed
H
2
= Reduced pressure n
2
= Reduced speed
Table 2.3
n
100%
50%
25%
12,5%
50% 100%
80%
80%
175HA208.10
Power ~n 3
Pressure ~n
2
Flow ~n
Figure 2.8
Flow :
Q1
Q2
=
n1
n2
Pressure :
H1
H2
=
(
n1
n2
)
2
Power :
P1
P2
=
(
n1
n2
)
3
Introduction to VLT® HVAC D...
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