The Siemens 3RT1517-2BB48-0KT5 is a SIRIUS power contactor in the S00 frame size — the smallest in the series, at 45 mm wide, 60 mm high, and 72 mm deep.
The coil picks up at 85 % of rated voltage (about 20.4 V) and drops out at 1.1× rated (26.4 V) — so on a nominal 24 V bus, it holds in during dips but releases cleanly on undervoltage. The main contacts are rated 12 A per NO and per NC at the rated value, and the auxiliary circuit carries the same 12 A per contact. For DC switching at 24 V, the contactor handles 10 A; at 60 V it's 2 A; at 110 V it drops to 1 A; at 220 V it's 0.3 A. On the AC side at 230 V it switches 6 A, at 400 V it's 3 A, at 440 V it's 0.8 A. Those numbers tell you the contactor is sized for moderate motor and resistive loads — not for high-current starters. Short-circuit protection is specified with a gL/gG fuse rated 20 A under Type 2 coordination — that's the fuse size that keeps the contactor repairable after a fault.
Wiring and installation
Both the main current circuit and the auxiliary/control circuit use spring-loaded terminals — no screwdriver needed for the wire connection, which speeds up panel wiring. The terminals accept 2x (0.25 to 2.5 mm²) solid or stranded wire, or 2x (24 to 14 AWG) for the main contacts.