Automatic MV reclosers, five major factors

System voltage: System voltage will be known. The recloser must have a voltage rating equal to system voltage.
Maximum fault current available at the recloser location: Maximum fault current will be known or can be calculated. The recloser interrupting must be equal to (or greater than) the maximum available fault current at the recloser location.
Maximum load current: The recloser continuous current rating must be equal to(or greater than) anticipated circuit load. For series-coil-type reclosers, the coil size can be selected to match the present load current, the anticipated future load current, or the substation transformer capacity.
Generally, a trip-current value of at least twice the expected load current is used.
Minimum-fault current within the zone to be protected: Minimum fault current that might occur at the end of the line section must be checked to confirm that the recloser will sense and interrupt this current.
Coordination with other protective devices on both the source and the load sides of the recloser.
Generally,recloser timing and sequences are selected to coordinate with the source-side devices.

Figure show several options to locate reclosers in a MV system.