3.1.1.5 Better Control
If a drive is used for controlling the flow or pressure of a system, improved control is obtained.
A drive can vary the speed of the fan or pump, obtaining variable control of flow and pressure. Furthermore, a drive can quickly
adapt the speed of the fan or pump to new flow or pressure conditions in the system.
Simple control of process (flow, level, or pressure) utilizing the built-in PI control.
3.1.1.6 Star/Delta Starter or Soft Starter not Required
When larger motors are started, it is necessary in many countries to use equipment that limits the start-up current. In more tradi-
tional systems, a star/delta starter or soft starter is widely used. Such motor starters are not required if a drive is used.
As shown in the following illustration, a drive does not consume more than rated current.
% F ull load cur r en t
& speed
Illustration 8: Start-up Current
3.1.1.7 Using a Drive Saves Money
The example in 3.1.1.8 Traditional Fan System without a Drive and 3.1.1.9 Fan System Controlled by Drives shows that a drive repla-
ces other equipment. It is possible to calculate the cost of installing the 2 different systems. In the example, the 2 systems can be
established at roughly the same price.
Use the VLT® Energy Box software that is introduced in chapter Additional Resources to calculate the cost savings that can be ach-
ieved by using a drive.
AJ363928382091en-000101 / 130R098318 | Danfoss A/S © 2021.04
Product Overview
VLT® Flow Drive FC 111
Design Guide