What this SIRIUS contactor is and where it lands
The Siemens 3RT1024-3XG28-0MV0-ZX95 is a SIRIUS-brand power contactor in the Size S0 frame, designed for switching motor loads and resistive loads in industrial control panels. It mounts on a 35 mm DIN rail per DIN EN 50022 using either screw or snap-on fastening, so it drops into a standard panel layout without adapters. Rated for AC-3 duty at 5.5 kW on a 400 V three-phase supply, it handles the typical motor starting curve for pumps, fans, and small compressors. The AC-4 rating of 12.5 A at 400 V covers reversing or inching applications where the contactor makes and breaks full-load current repeatedly.
Terminal design and wiring constraints
Main power circuit terminals are screw-type, accepting 2x (0.25... 2.5 mm²) solid or 2x (1... 2.5 mm²) stranded, with a maximum of 2x 10 mm². Auxiliary and control circuit terminals are spring-loaded, which speeds wiring on the control side and holds well under vibration in a panel. For Type 2 coordination (no-weld on fault), the required upstream fuse is gL/gG 25 A. For Type 1 coordination (allow contactor replacement after fault), the fuse can be 63 A. That gives the panel designer flexibility on selectivity with downstream motor protection.
Environmental and mounting fit
The contactor is rated IP20 on the front of the enclosure and IP00 at the terminals — meaning the terminal area is not finger-safe, so it needs to live inside a panel with a door or cover. Operating ambient temperature spans -25 to +60 °C, which covers most indoor plant-floor conditions including unheated warehouses. Dimensions are 45 mm wide, 88 mm high, and 140 mm deep. Side-by-side mounting is permitted, so you can gang multiple contactors on the same rail without a mandatory gap, saving panel width. Pollution degree 3 means it's rated for conductive pollution or dry non-conductive pollution that becomes conductive due to condensation — typical in industrial environments not climate-controlled.
Auxiliary contact and surge suppression
The contactor includes 2 instantaneous auxiliary contacts. The surge suppressor is built with RC elements, which limits coil voltage spikes on dropout — relevant if the control circuit shares a DC supply with electronics like a PLC output. Auxiliary contact ratings are given for DC switching: 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, and 0.3 A at 220 V. These are the DC-13 (inductive) values, so they govern the contact life when switching small relays or contactor coils directly. Mechanical life is typical 10 million operations, which is standard for the S0 frame and sufficient for most cyclic applications.