Danfoss VLT AQUA Drive Design Manual page 19

VLT ® AQUA Drive Design Guide
2.7.6. Cos φ compensation
Generally speaking, an adjustable frequency drive with a cos φ of 1 provides power factor cor-
rection for the cos φ of the motor, which means that there is no need to make allowance for the
cos φ of the motor when sizing the power factor correction unit.
2.7.7. 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 an adjustable frequency drive is used.
As illustrated in the figure below, an adjustable frequency drive does not consume more than rated
current.
MG.20.N2.22 - VLT ® is a registered Danfoss trademark.
2. Introduction to the VLT AQUA Drive
1 = VLT AQUA Drive
2 = Star/delta starter
3 = Soft-starter
4 = Start directly on line power
2
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