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
adjustable frequency drive according to the pressure drop.
Figure 4.20: D frame Derating vs. Pressure Change
Drive air flow: 450 cfm (765 m
3
/h)
Figure 4.21: E frame Derating vs. Pressure Change (Small Fan), P315
Drive air flow: 650 cfm (1105 m
3
/h)
Figure 4.22: E frame Derating vs. Pressure Change (Large Fan) P355-P450
Drive air flow: 850 cfm (1445 m
3
/h)
VLT HVAC Low Harmonic Drive Instruction
Manual
4 How to Install
MG.16.A1.22 - VLT
®
is a registered Danfoss trademark
4-25
4