The Siemens SIRIUS 3RT1026-1AP00 is a size S0 power contactor with three normally-open main contacts, rated for motor switching at 11 kW in AC-2 duty at 400 V and 15.5 A in AC-4 at 400 V. It's a current-production part, still actively listed by Siemens.
At 45 mm wide and 85 mm tall, it takes a single 45 mm slot on the rail — standard for S0 frame contactors. Depth is 91 mm, which includes the screw terminals; leave clearance for wiring.
Terminal and Wiring
Main and auxiliary circuits both use screw-type terminals. Main terminals accept 2x (1 to 2.5 mm²) solid/stranded, 2x (2.5 to 6 mm²), or max 2x 10 mm². Auxiliary terminals take 2x (0.5 to 1.5 mm²) solid, 2x (0.75 to 2.5 mm²), or max 2x (0.75 to 4 mm²). AWG equivalents are listed for both.
For Type 1 coordination, the required upstream fuse is gL/gG 100 A; for Type 2 coordination, it's gL/gG 35 A.
Front of the contactor is IP20 (finger-safe); the terminal area is IP00. The contactor carries a substance prohibition date of 01.07.2006, indicating RoHS compliance from that date.