Let K be a complete
discrete valued field of unequal characteristic (0,p). The aim of this paper is to
describe the semi-stable models for covers PK1→ PK1 of degree p, unramified
outside r ≤ p points and totally ramified above one of them, under the assumtion
that the ramification locus has a particular reduction type (which always occurs if
r ≤ 4). We are principally concerned with the minimal semi-stable models which
separate the ramified fibers.