The Siemens 3RT2017-1KB42 is a SIRIUS coupling contactor, Size S00, designed to switch loads in control panels where galvanic isolation or signal-level switching is needed between circuits. The contactor is rated for 10 A at 24 V, 2 A at 48 V and 60 V, 1 A at 110 V, 0.9 A at 125 V, 0.3 A at 220 V, and 3 A at 400 V. At 230 V it carries a 2 hp motor load. The 24 VDC coil is the key spec for fit — this is a DC-operated coupling contactor, not a standard AC-coil power contactor. No auxiliary switch is built in; any auxiliary contacts must be added separately.
For two conductors per terminal, the range is 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or 2x 4 mm². The main contact configuration is 20-12 (normally open and normally closed).
Switching frequency and duty
Maximum switching rate depends on duty: 1000 operations per hour at AC-1 (resistive), 750 ops/h at AC-2 and AC-3 (motor starting/running), 750 ops/h at AC-3e (enhanced motor), and 250 ops/h at AC-4 (plugging/inching). The 30 million mechanical operations give a long service life in cyclic applications.