FC101 Design Guide

Figure 3.3 describes the dependence of ow, pressure, and
power consumption on RPM.
n
100%
50%
25%
12,5%
50% 100%
80%
80%
175HA208.10
Power ~n
3
Pressure ~n
2
Flow ~n
Figure 3.3 Laws of Proportionally
Flow: 
Q
1
Q
2
 = 
n
1
n
2
Pressure: 
H
1
H
2
 = 
n
1
n
2
2
Power:
P
1
P
2
 = 
n
1
n
2
3
Q = Flow P = Power
Q
1
= Rated ow P
1
= Rated power
Q
2
= Reduced ow P
2
= Reduced power
H = Pressure n = Speed control
H
1
= Rated pressure n
1
= Rated speed
H
2
= Reduced pressure n
2
= Reduced speed
Table 3.1 The Laws of Proportionality
3.1.4 Comparison of Energy Savings
The Danfoss frequency converter solution oers major
savings compared with traditional energy saving solutions
such as discharge damper solution and inlet guide vanes
(IGV) solution. This is because the frequency converter is
able to control fan speed according to thermal load on the
system, and the frequency converter has a built-in facility
that enables the frequency converter to function as a
building management system, BMS.
Figure 3.3 shows typical energy savings obtainable with 3
well-known solutions when fan volume is reduced to 60%.
As the graph shows, more than 50% energy savings can be
achieved in typical applications.
130BA782.10
Discharge
damper
Less energy savings
IGV
Costlier installation
Maximum energy savings
Figure 3.4 The 3 Common Energy Saving Systems
Figure 3.5 Energy Savings
Discharge dampers reduce power consumption. Inlet guide
vanes oer a 40% reduction, but are expensive to install.
The Danfoss frequency converter solution reduces energy
consumption with more than 50% and is easy to install. It
also reduces noise, mechanical stress, and wear-and-tear,
and extends the life span of the entire application.
Product Overview Design Guide
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