What it is and where it lands
The Siemens 3RT1034-3BB40-ZN88X95 is a SIRIUS S2-frame power contactor rated for 18.5 kW at 500 V AC-3, with a 24 VDC coil. It mounts via screw and snap-on onto 35 mm DIN rail per EN 50022, so it drops straight into a standard panel — no adapter plate needed. The IP20 front and IP00 terminal area mean it's safe for finger contact on the face but the wiring zone expects enclosure protection.
Key ratings and what they mean for fit
The AC-3 motor rating of 18.5 kW at 500 V tells you this contactor handles a standard 25 hp induction motor on a 480 V line. At 400 V AC-4 it's rated 29 A — that's the reversing or plugging duty cycle, so if your application jogs or brakes the load frequently, this is the number that governs contact life, not the AC-3 figure. Coil pickup at 24 VDC draws 10 A inrush (at rated value), holding at 0.8 A initial. Dropout time is 20 to 30 ms, arcing time 10 to 15 ms — that's fast enough for most safety circuits but verify your PLC cycle time if you're sequencing multiple contactors. Terminals accept solid 2x (0.25 to 2.5 mm²) or stranded 2x (0.75 to 25 mm²) on the main circuit — screw-type, so you'll need a torque driver for the larger lugs. The 55 mm width and 112 mm height leave room for auxiliary contact blocks alongside.
Integration notes
Side-by-side mounting is permitted, so you can gang multiple contactors on the same rail without derating spacing. Operating temperature range is -25 to +60 °C; storage from -55 to +80 °C. Pollution degree 3 means it's suited for industrial environments with conductive dust or occasional condensation — typical for a control panel in a factory hall.