SIRIUS Size S0 power contactor, 110 V DC coil
The Siemens 3RT1025-3BF40 is a SIRIUS-brand power contactor in the Size S0 frame, rated for a 110 V DC coil. The AC-2 rating at 400 V is 7.5 kW, covering slip-ring motor duty; the AC-4 rating at 400 V is 15.5 A, for reversing or inching applications where the contactor makes and breaks stalled-rotor current. At 690 V the contactor handles 11 kW, and at 500 V it handles 10 kW.
Mounting and terminal data
Main circuit terminals accept solid or stranded copper: 2x (1 to 2.5 mm²), 2x (2.5 to 6 mm²), or max 2x 10 mm². Auxiliary/control terminals accept 2x (0.25 to 2.5 mm²). AWG equivalents are 2x (16 to 12), 2x (14 to 10), and 1x 8 for the main circuit. Front-face protection is IP20 (finger-safe); the terminal area itself is IP00 (open to touch during wiring).
Coordination and auxiliary ratings
Auxiliary contact ratings: 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, 0.3 A at 220 V, 6 A at 230 V, 3 A at 400 V. The AC-12 maximum operating current is 10 A. No instantaneous contact is fitted.