SIRIUS S2 Power Contactor — 3RT1034-1BD44
It is rated for 18.5 kW at 500 V and 10 kW at 690 V under AC-3 duty, which covers the majority of three-phase induction motor applications up to that power.
The AC-3 motor-switching rating of 18.5 kW at 500 V and 10 kW at 690 V defines the maximum three-phase motor load this contactor can switch under typical starting conditions (6–8× locked-rotor current). For a 400 V supply, the corresponding AC-3 current is 29 A — the value that governs thermal sizing in a motor starter. The -25 °C lower limit is common for indoor panel installations; if the panel sits in an unconditioned outdoor shelter in a cold climate, verify the ambient stays above that threshold. The auxiliary contact ratings cover 24 VDC at 10 A down to 220 VDC at 0.3 A — these are resistive-load figures; for inductive DC loads like relay coils, derate or add a free-wheeling diode across the load.
RoHS compliance is confirmed per the substance prohibitance date of May 1, 2012, covering the EU RoHS directive. No separate UL or CSA listing is shown in the spec record, but the SIRIUS series broadly carries these approvals — confirm the specific certification mark on the nameplate if the installation requires a UL-listed device.
Integration Notes
The minimum permissible cross-section at 40 °C ambient is 16 mm² for the main circuit, which guides feeder sizing. Switching frequency varies by duty: up to 1,200 operations per hour at AC-1 (resistive), 1,000 at AC-3 (motor), and 250 at AC-4 (plugging/inching). For high-cycle applications like reversing starters, the AC-4 limit is the binding constraint.