
2.5.13 The VLT Solution
While dampers and IGVs work to maintain a constant pressure in the ductwork, a frequency converter solution saves much
more energy and reduces the complexity of the installation. Instead of creating an artificial pressure drop or causing a
decrease in fan efficiency, the frequency converter decreases the speed of the fan to provide the flow and pressure required
by the system.
Centrifugal devices such as fans behave according to the centrifugal laws. This means the fans decrease the pressure and
flow they produce as their speed is reduced. Their power consumption is thereby significantly reduced.
The PI controller of the VLT HVAC Basic Drive can be used to eliminate the need for additional controllers.
Frequency
converter
Frequency
converter
D1
D2
D3
Cooling coil
Heating coil
Filter
Pressure
signal
Supply fan
VAV boxes
Flow
Flow
Pressure
transmitter
Return fan
3
3
T
130BB455.10
Introduction to VLT HVAC Ba... VLT HVAC Basic Drive Design Guide
16 MG.18.C2.02 - VLT
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