The Siemens SENTRON 5SV8705-0KK is a summation current transformer designed for AC systems, type A per the classification. It carries a 500 A rated operational current and a 140 mm internal diameter, sized to bundle multiple conductors through the core for residual-current monitoring in distribution panels.
Mounts with screw-type terminals accepting 0.13 mm² to 2.1 mm² conductors. The 140 mm ID passes multiple phase conductors and the neutral for summation measurement. Wire runs to the connected RCD or relay must stay under 10 m to maintain measurement accuracy and avoid nuisance tripping. IP20 at the connection terminals means it lives inside an enclosure — no exposed wet or dusty environments.