Types Of Soft Starter - Danfoss VLT Pocket Manual

Types of Soft Starter: What are the diff erent types
of soft starters?
There are three diff erent types of soft starter which off er diff erent
features and control the motor in diff erent ways.
1. Torque controllers control only one phase during start. This reduces
the torque shock at start but does not reduce start current. Torque
controllers must be used in conjunction with a direct on-line starter.
2. Soft starters which control two phases can reduce start current as
well as eliminating torque transients, and are suitable for normal
and heavy duty loads, but not severe loads. The start current on the
uncontrolled phase is slightly higher than the two controlled phases.
3. Soft starters which control all three phases provide the maximum
level of soft start control and are the only soft start solution that is
suitable for severe duty applications.
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VLT Soft Starter Pocket Guide