Perhaps a rather rudimentary question but what is “full mode” protection? I assume that it is a combination of common and differential modes but it seems to me that it is generally common mode that is provided.
I think CT1 still effectively provides protection against common-mode transients. For example, if there is 4kV across L1-L2, then there is a total of 4kV across L1-E-L2, so a minimum of 2kV across at least one of L1-E and L2-E (and in fact most likely 4kV L1-E and 0V L2-E or vice versa). So at least one of the SPDs will trigger.
I think CT1 still effectively provides protection against common-mode transients. For example, if there is 4kV across L1-L2, then there is a total of 4kV across L1-E-L2, so a minimum of 2kV across at least one of L1-E and L2-E (and in fact most likely 4kV L1-E and 0V L2-E or vice versa). So at least one of the SPDs will trigger.
