In fact, in the ATVProcess 690 with have 3 references.
ATV630 & ATV930 ending in "S6X" mandatory line reactor.
ATV630 & ATV930 ending in "S6" optional line reactor.
ATV630 & ATV930 ending in "Y6" optional line reactor.


The "X" of at the end of S6X is to says that there is no EMC filter on the drive ,it is not directly like with line reactor.
Whatever on S6X drive ,line choke is mandatory ,and on S6 or Y6 ,line reactor is optional (regarding short circuit current).
Why it is optional for S6 and Y6.
Because there is an internal choke inside these references.
For the reference S6X there is no internal choke, and this is why it is mandatory to add a line reactor.

Released for: Schneider Electric India