What It Is and Where It Fits
The Siemens SIRIUS 3RT2018-2BW42 is a Size S00 power contactor with a 48 VDC coil, designed for switching motor loads in industrial control panels. Its 45 mm width and snap-on mounting onto 35 mm DIN rail per DIN EN 60715 mean it fits standard panel layouts without special brackets. The spring-type terminals accept solid or stranded conductors from 0.5 to 4 mm², and the operating temperature range of -25 to +60 °C covers most indoor industrial environments without derating concerns.
Key Ratings and What They Mean for Your Application
The 48 VDC coil is the control voltage you need to supply; the contactor pulls in reliably at 0.8 of rated voltage (38.4 V) and holds in. The auxiliary contact ratings are given per voltage: 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 — these are the switching capacities for the built-in auxiliary switch, not the main poles. Switching frequency limits are duty-dependent: up to 1000 operations per hour for AC-1 resistive loads, 750/h for AC-2 and AC-3 motor starting, and 250/h for AC-4 plugging/reversing. The AC-3e rating also caps at 750/h. These numbers govern contact life; exceeding them accelerates wear.
Mounting and Clearance
The contactor can be mounted in any orientation within ±180° rotation on a vertical surface, and can be tilted forward/backward by ±22.5°. Required clearances for arc containment: 10 mm upwards, 10 mm forwards, 10 mm downwards, and 6 mm at the sides. The arcing time is 10 to 15 ms, and the DC switching time is 7 to 13 ms.