Is it possible to use ATS48 Soft Starter without bypass contactor.

The ATS48 can work without by-pass contactor, but pay attention to not bypass is the drop voltage across the thyristors witch generate power losses and heating. We can say than in 95% of the case the bypass mode is used to prevent this problem principally.
The bypass is use for eliminate the heating inside the ATS48.

Released for: Schneider Electric India