Abstract: A contactor has a body constituted by a base common to two parallel walls each having on its internal face a rib to guide fixed elements of a removable electro-magnet having means to cooperate with the ribs. The fixed elements form a slide having resilient locking means cooperating with stop means on an adjacent wall such that, in a first position, the core is disposed opposite the armature, the core being assembled to the body by first support members, and the winding being secured to the body by its own independent support members. In a second position, the core remains engaged with the body and extends from the body so that the winding support means are freed from the rib, and the winding can be separated from the core.