FC101 Design Guide

3.1.6 Better Control
If a frequency converter is used for controlling the ow or
pressure of a system, improved control is obtained.
A frequency converter can vary the speed of the fan or
pump, obtaining variable control of ow and pressure.
Furthermore, a frequency converter can quickly adapt the
speed of the fan or pump to new ow or pressure
conditions in the system.
Simple control of process (ow, level, or pressure) utilizing
the built-in PI control.
3.1.7 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 traditional systems, a star/delta starter or soft
starter is widely used. Such motor starters are not required
if a frequency converter is used.
As illustrated in Figure 3.8, a frequency converter does not
consume more than rated current.
Full load
% Full-load current
& speed
500
100
0
0 12,5 25 37,5 50Hz
200
300
400
600
700
800
4
3
2
1
175HA227.10
1
VLT
®
HVAC Basic Drive FC 101
2 Star/delta starter
3 Soft starter
4 Start directly on mains
Figure 3.8 Start-up Current
3.1.8 Using a Frequency Converter Saves
Money
The example in chapter 3.1.9 Without a Frequency Converter
shows that a frequency converter replaces other
equipment. It is possible to calculate the cost of installing
the 2 dierent 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 1.5 Additional Resources to calculate the cost
savings that can be achieved by using a frequency
converter.
Product Overview Design Guide
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