A power and control unit for low or medium voltage applications operatively coupable to a low or medium voltage apparatus and to a protection relay having a trip circuit supervision. The power and control unit for low or medium voltage applications according to the invention comprises: a binary input which is operatively coupable with said protection relay; a control unit operatively coupled to said binary input and operatively coupable to said low or medium voltage apparatus; a failure and continuity detection unit operatively coupled to said binary input and that can be enabled and disabled; an enabling unit operatively coupled to said failure and continuity detection unit and to said control unit and operatively coupable to said low or medium voltage apparatus.