Siemens SIRIUS 3RT2018-2LB42-2LA0 — S00 Contactor, 24 VDC Coil, Spring-Terminal
The Siemens 3RT2018-2LB42-2LA0 is a SIRIUS contactor in frame size S00, designed for switching motor loads and resistive circuits in industrial control panels. It carries a 24 VDC magnet coil terminated via spring-type terminals — no screw torque to verify, which saves time on the panel build and eliminates a common field failure point (loose screw connections under vibration). Main contacts are rated for 20 A down to 12 A (the range covers the standard AC-3 motor duty and AC-1 resistive load curves for this frame). The auxiliary switch is integrated, with switching capacity documented per the DC voltage rail: 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, 3 A at 400 V, 14 A at 480 V, 2 A at 500 V, 11 A at 600 V, and 1 A at 690 V — these are the values to use when sizing the control circuit, not the main power path.
Mounting and Integration
Mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 60715. The S00 footprint is 45 mm wide by 70 mm high by 121 mm deep — a standard slot that fits alongside other SIRIUS S00 components on the same rail without stealing extra width. Permitted mounting positions include hanging and on a horizontal surface; clearance distances are 10 mm upwards, 10 mm forwards, 10 mm downwards, and 6 mm at the side. Conductor terminations on the spring-type terminals accept solid or stranded wire: 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), 2x 4 mm², or 2x (0.5 to 4 mm²). Strip length per the terminal manufacturer's recommendation — the spring cage holds firmly when the conductor is fully inserted.
Environmental and Timing
Operating temperature range is -40 to +70 °C; storage range is -55 to +80 °C. The coil pick-up and drop-out times at DC are 7 to 20 ms, and the arcing time on the main contacts is 10 to 15 ms. Mechanical endurance is rated at 30,000,000 operations typical — this is the mechanical life, not the electrical life under load, which will be lower depending on the switching duty. The maximum switching rate under AC-4 duty (plugging / inching) is 250 operations per hour. For continuous motor starting (AC-3), the rate is higher — consult the thermal derating for your specific load current.