SIRIUS S0 direct on-line starter with spring terminals
The 3RA2120-4EE27-0AP0 is a Siemens SIRIUS direct on-line starter in Size S0, combining a 3RT2027-2AP00 contactor and a 3RA2921-2AA00 link module into one rail-mounted unit.
DIN rail fit and terminal work
Width is 45 mm — that's a single 9 mm DIN module slot on a 35 mm rail, leaving the adjacent positions open for other feeders or control gear. Depth of 107 mm and height of 243 mm mean it fits a standard 400 mm deep enclosure with room for wire bending behind the door. Main current circuit uses spring-loaded terminals, so you push in the stripped conductor without a screwdriver for the power wires — saves time on repetitive builds.