What this 5SY7320-8CC does on the line
On DC circuits it's rated up to 72 V, so it handles control power supplies and DC bus protection within that voltage ceiling.
It's 3 width units (54 mm wide), 90 mm tall, and 76 mm deep with an installation depth of 70 mm. Terminals accept solid or stranded copper from 0.75 to 35 mm², with a tightening torque of 2.5 to 3.5 N·m. Both top and bottom have combined terminals (screw and clamp), so you can daisy-chain or ring-tongue without adapters. Rated IP20 with conductors connected — fine inside a closed enclosure, not for wet or dusty locations.
Halogen-free and silicon-free construction, so it won't outgas corrosive compounds in sealed enclosures or near sensitive electronics. Humidity tolerance is specified: max 95% at 55 °C, derating to 55% at 70 °C and 35% at 75 °C. Sealable terminals allow lockout/tagout compliance. Touch protection is built in — fingers won't reach live parts when wired.