External ducts
If additional duct work is added externally to the Rittal cabinet the
pressure drop in the ducting must be calculated. Use the charts below
to derate the frequency converter according to the pressure drop.
90
80
70
60
50
40
30
20
10
0
0
0.5
4.9
13
27.3
45.9
66
89.3 115.7 147
(%)
(Pa)
Pressure Increase
Dr
iv
e D
er
ating
130BB007.10
Illustration 3.29: D frame Derating vs. Pressure Change
Drive air flow: 450 cfm (765 m
3
/h)
90
80
70
60
50
40
30
20
10
0
(%)
Dr
iv
e D
er
ating
0
0
0.1
3.6
9.8 21.5 43.4
76
237.5
278.9
(Pa)
Pressure Change
130BB010.10
147.1
Illustration 3.30: E frame Derating vs. Pressure Change
(Small Fan), P315T5 and P450T7-P500T7
Drive air flow: 650 cfm (1105 m
3
/h)
90
80
70
60
50
40
30
20
10
0
(%)
Dr
iv
e D
er
ating
0
0.2
0.6
2.2
5.8
11.4 18.1 30.8
152.8 210.8
(Pa)
Pressure Change
130BB011.10
69.5
Illustration 3.31: E frame Derating vs. Pressure Change
(Large Fan), P355T5-P450T5 and P560T7-P630T7
Drive air flow: 850 cfm (1445 m
3
/h)
90
80
70
60
50
40
30
20
10
0
(%)
Dr
iv
e D
er
ating
0
25
50
75
100
125
150
175
225
130BB190.10
200
Pressure Change
Illustration 3.32: F1, F2, F3, F4 frame Derating vs. Pres-
sure Change
Drive air flow: 580 cfm (985 m
3
/h)
3 Mechanical Installation
VLT HVAC Drive High Power Operating In-
structions
38
MG.11.F3.02 - VLT
®
is a registered Danfoss trademark
3