Alternate Director u/s 313

How come an Alternate director is a non rotational director?

A director in Alternate director u/s 313 is appointed in place of the original director and he can hold office till such time as permissible to the original director, then shouldn't his nature be same as the original director. If original director is rotational then so should he and if original director is non rotational, then he should also be non rotational.