Does the supply cable between the Siemens soft starter and the motor need shielding

For 3RW soft starters, it is sufficient to use an unshielded main loop cable between the motor and the 3RW soft starter.

The main reasons are as follows:

The frequency of the power supply on the motor terminal is steady at 50 or 60 Hz throughout the soft starter operation

After the soft start is complete, the main loop switches to the internal bypass contactor in parallel, and the current and voltage waveforms are perfect sine waves.

The soft starter is operated using phase Angle control during soft start and soft stop. Phase Angle control achieves the purpose of step-down starting by controlling the thyristor turn-on time. Only when the pulse triggers the thyristor turn-on, the harmonic wave will be generated, and the duration is very short. So it's negligible.