Preparing for soft starter installation
The peripheral devices that are needed around the soft starter need to be specified before planning the installation of the soft
The soft starter can be wired to start a normal 3-wire motor or inside-delta on a six-wire motor. The installation and wiring of
the soft starter is similar for the normal and the inside-delta connections, but there may be implications for the enclosure size
and cable length, as well as the selection of external bypass contactor for the different ways of connecting the motor.
Normal Delta 3-wire connection
The diagram below shows the connection diagram for the soft starter with and without built-in bypass contactor, for normal 3-
wire connection. With this method of connecting the motor, the full motor starting current flows through the soft starter
switching elements during start-up. After start-up and if a built-in or external bypass contactor is used, the full running current
of the motor flows through the contactor. If no bypass contactor is used, the motor's continuous running current flows through
the soft starter switching elements.
With this method of installation, the bypass contactor must be scaled for the full running current of the motor. Only three
cables are needed to run the distance to the motor.
18 Installation Instructions
Figure 4 – Soft starter circuit diagram for 3-wire delta motor