2.6.7 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 Illustration 2.8, 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
Illustration 2.8 Start-up Current
1
VLT
®
HVAC Basic Drive FC 101
2 Star/delta starter
3 Soft-starter
4 Start directly on mains
Table 2.5 Legend to Illustration 2.8
2.6.8
Using a Frequency Converter Saves
Money
Example 2.6.9 Without a Frequency Converter shows that a
lot of equipment is not required when a frequency
converter is used. 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.
Product Overview
VLT
®
HVAC Basic Drive FC 101 Design Guide
MG18C502 - Rev. 2013-09-06 15
2 2
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