It is not recommended to use step-up transformer on ATS48/ATS480 output.
Instead of ATS, the suggestion is to use VSD + Sinus filter + step up transformer combination for this requirement.
The dv/dt output voltage of the ATS48/ATS480 will be the cause of current and voltage oscillations and overvoltages.
Thyristors can burn in overvoltage and the insulation of the motor has to be high enough.
The magnetic saturation of the transformer will cause overcurrents which will damage the thyristors.
In case of micro cut of the main supply, overcurrent will appear.