FC101 Design Guide

3.1.13 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 articial pressure

drop or causing a decrease in fan eciency, the frequency

converter decreases the speed of the fan to provide the

ow and pressure required by the system.

Centrifugal devices such as fans behave according to the

centrifugal laws. This means that the fans decrease the

pressure and ow they produce as their speed is reduced.

Their power consumption is thereby signicantly reduced.

The PI controller of the VLT

HVAC Basic Drive FC 101 can

be used to eliminate the need for additional controllers.

Frequency

converter

Frequency

converter

Cooling coil

Heating coil

Filter

Pressure

signal

Supply fan

VAV boxes

Flow

Pressure

transmitter

Return fan

130BB455.10

Figure 3.11 Variable Air Volume

Product Overview

VLT

HVAC Basic Drive FC 101