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Chapter 4 Applications
44 CNT-APG002-EN
Example 2: Three-stage fan system
The staging points are calculated as follows:
1. Calculate the overlap range.
2. Calculate the first stage control points.
3. Calculate the second stage control points.
4. Calculate the third stage control points.
The results are summarized in Figure 32.
Figure 32: Three-stage fan on and off points
Overlap range
80%
stage count 1+
-----------------------------------------
80%
31+
-------------20%===
Stage 1
On: control value 10% 2 20× %()+50%=≥
Off: control value 10%<
=
Stage 2
On: control value 10% 3 20× %()+70%=≥
Off: control value 10% 1 20× %()+30%=<
=
Stage 3
On: control value 10% 4 20× %()+90%=≥
Off: control value 10% 2 20× %()+50%=<
=
Control value (%)
0 10 20 30 40 50 60 70 80 90 100
Fan 2
Fan 1
No. of
fans
Fan 3
3
2
1
0