Siemens 3RT2038-1NB34 — SIRIUS Size S2 Power Contactor
The Siemens 3RT2038-1NB34 is a SIRIUS-branded power contactor in the size S2 frame, designed for switching motor loads and resistive circuits in industrial control panels. It mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 60715, fitting standard enclosure layouts. The coil accepts 20-33 VAC/DC, with a pick-up threshold at 0.8x rated and drop-out at 1.1x full-scale value — meaning it holds in reliably down to about 16 V and releases cleanly above 36 V. Main contacts are configured as 3-pole normally open (3 NO), rated for AC-1, AC-2, AC-3, and AC-4 duty cycles. At AC-3 (motor switching), the maximum operating rate is 500 cycles per hour; at AC-4 (inching/jogging), it drops to 150 cycles per hour due to higher arc stress. Mechanical life is rated at 10 million operations typical.
Mounting and Clearance
Mounting position is flexible: the contactor can be rotated ±180° on a vertical surface and tilted forward/backward ±22.5°. Minimum clearances around the unit: 10 mm upwards, 10 mm forwards, 10 mm downwards, and 6 mm to the side. These spacings ensure adequate arc-quenching and heat dissipation in a crowded panel. The 55 mm width and 174 mm depth fit standard 600 mm deep enclosures with room for wiring ducts.
Coil and Control Circuit
Coil terminals are screw-type, accepting 2x 0.5 to 2.5 mm² solid or stranded wire. Inrush current peaks at 3 A; holding (sealing) power is 2 VA at both 50 Hz and 60 Hz. At 24 V rated value, holding current is 6 A; at 48 V it drops to 2 A, and at 220 V to 0.3 A. Opening time is 30-55 ms for both AC and DC supplies, with an arcing time of 10-20 ms. These timing figures matter for coordination with upstream short-circuit protection devices — the arc must clear before the breaker's magnetic trip reacts.
Environmental and Compliance
Operating temperature range is -25 to +60 °C; storage range is -55 to +80 °C. The SIRIUS series typically carries UL, CSA, and CE certifications (confirm specific marks with the factory datasheet). RoHS and REACH compliance documentation is available from the manufacturer.