What This Part Does and Where It Fits
The Siemens SIRIUS 3RT1034-1AQ20 is a size S2 power contactor rated for switching motor loads up to 18.5 kW at 500 V under AC-3 duty (standard squirrel-cage motors), and 15 kW at 400 V under AC-2 duty (slip-ring motors or moderate starting). It handles 10 kW at 690 V, so it can serve 690 V delta-connected motors in European or marine panels. It mounts on a 35 mm DIN rail per EN 50022 using either the screw clamp or the integrated snap-on latch. Side-by-side mounting is allowed, so you can gang multiple contactors on the same rail without a gap — useful for compact motor control centers.
Key Ratings and What They Mean for Your Panel
The AC-3 rating of 18.5 kW at 500 V is the headline number for motor starting — it tells you this contactor can handle the inrush of a standard induction motor up to that power level. The AC-2 rating of 15 kW at 400 V is for more demanding applications like wound-rotor motors or frequent jogging, where the contacts make and break under load more often. Mechanical life is rated at 10 million operations typical, which is standard for a SIRIUS size S2. Electrical life depends on the switching category and load current — the datasheet derating curves apply, but for typical AC-3 motor switching at rated current you can expect hundreds of thousands of operations before contact wear becomes a concern. The auxiliary contact block (integrated or add-on) is rated at 10 A at 24 V, 6 A at 230 V, and 3 A at 400 V — enough for PLC inputs, pilot lights, or interlocking relays in the control circuit. The main power terminals accept solid wire from 0.5 to 4 mm² (two conductors per clamp) and stranded up to 25 mm², so it covers most panel wiring sizes without needing adapters. Operating temperature range is -25 to +60 °C, with storage down to -55 °C. The front of the contactor is IP20 (finger-safe), while the terminal area is IP00 — meaning the power connections are exposed and need to be inside an enclosure or guarded by the panel door.
Wiring and Integration Notes
Screw-type terminals on the main circuit: tighten to the torque specified in the Siemens documentation (typically 2-2.5 Nm for the main poles). The auxiliary contacts use smaller screw terminals. Use ferruled stranded wire for reliable connections in high-vibration environments like conveyor lines or compressor skids. Coil operates on 50 or 60 Hz with a voltage tolerance of 0.8 to 1.1 times rated at 50 Hz, and 0.85 to 1.1 at 60 Hz. Pick-up time is 7 to 20 ms, arcing time 10 to 15 ms — fast enough for most sequencing but worth noting if you have very tight timing requirements in a safety circuit. The contactor occupies 55 mm width on the DIN rail, with a depth of 115 mm and height of 112 mm. That's a standard size S2 footprint — it fits alongside other SIRIUS components in a pre-drilled panel layout. Side-by-side mounting means no spacing required between units, so you can pack multiple contactors into a 600 mm wide enclosure.
Sourcing and Cross-Reference Reality
This is an active, current-production part. For new designs or spares, it's a straightforward order through Siemens distribution. No last-time-buy or obsolescence concerns. If you're looking at a panel originally specified with a 3RT1036-1AB00 (a larger size S3 contactor), the 3RT1034-1AQ20 will not drop in without rewiring — the S2 has a different footprint and lower current ratings. The 3RT1034-1AQ20 is the correct size for motor loads up to 18.5 kW at 500 V; step up to the S3 frame for higher currents or larger motors.