SIRIUS S3 power contactor — what it is and what it does
The Siemens 3RT2046-1SB30 is a SIRIUS-brand power contactor in frame size S3, designed for switching motor loads and resistive loads in industrial control panels. It mounts via screw fixing or snaps onto a 35 mm DIN rail per DIN EN 60715, and the mounting position allows ±180° rotation on a vertical surface plus ±22.5° tilt forward/backward — useful when you're squeezing it into a crowded enclosure and need to orient the coil terminals toward the gland plate. The coil accepts 21–33 V AC or DC (rated value), with a pickup threshold of 0.8× rated and a full-scale dropout of 1.1× rated — so on a nominal 24 VDC control supply it pulls in cleanly at about 17 V and drops out reliably if the supply sags below 26 V. Inrush current peaks at 2.2 A, steady-state draw is 2.4 VA at both 50 and 60 Hz. The magnet coil uses screw-type terminals, same as the main and auxiliary contacts. Main contact wiring accepts solid conductors from 2.5 to 16 mm² or stranded from 6 to 70 mm² — that covers everything from a 4 mm² motor feed up to a 50 mm² supply cable without needing adaptor lugs. Auxiliary contact wiring takes 2×(0.5–1.5 mm²) solid or 2×(0.75–2.5 mm²) stranded.
Switching frequency and duty-cycle limits
This contactor is rated for different maximum switching rates depending on the utilisation category: 900 operations per hour in AC-1 (resistive), 850 in AC-3 (squirrel-cage motor starting), 350 in AC-2 (slip-ring motor), and 250 in AC-4 (plugging/inching). The AC-3e rating matches the AC-3 figure at 850 ops/h. Arcing time sits between 10 and 20 ms, and the make/break times (AC and DC) are both 38–57 ms — consistent, predictable switching for sequenced starter groups. Mechanical endurance is listed at 5 million operations typical.
Lifecycle and sourcing posture
The listed MTBF of 52 years (456,000 hours) is a calculated reliability figure under continuous rated load at 40 °C ambient — useful for a reliability-engineering review but not a warranty or guaranteed service life. It tells you the design target for random-failure rate is low enough that the contactor is unlikely to be the weakest link in a motor starter assembly.
Panel integration and clearances
Dimensions: 70 mm wide, 140 mm high, 152 mm deep. Minimum clearances to adjacent components: 10 mm upward, 10 mm downward, 20 mm forward, 10 mm to the side. That 152 mm depth is the body alone — factor in the screw-terminal projection and the coil-terminal screws when you're laying out the DIN-rail spacing against the enclosure back wall. Operating temperature range is –25 to +60 °C; storage from –55 to +80 °C.