VE5-1 Mechanical and Electrical Interlock Unit. VE5-1 is a mechanical and electrical interlock unit used for the mechanical and electrical interlocking of two contactors of the A contactor serie, in the case, e.g. of reversing contactors, changeover contactors or star-delta starters. VE5-1 includes 2 built-in N.C. interlocking contacts allowing to create the electrical interlocking with wiring to the respective contactor's coils.