The Siemens 3RB2036-1UD0 is a SIRIUS solid-state overload relay for three-phase motor protection. It's a current-production part, so you're not hunting for NOS or a replacement line item. That spring-clamp on the aux side saves time on the panel — no screwdriver needed for those connections.
Mounts directly onto a contactor via the fastening method — no DIN rail required if you're pairing it with a SIRIUS contactor. Mounting position is any, which is a nice flexibility when you're cramming a panel. Side clearance needed is 6 mm. Depth is 109 mm, width 55 mm, height 92 mm. That's a compact footprint for a three-pole solid-state overload. Shock resistance rated at 15g / 11 ms, and surge voltage resistance at 6 kV. EMC immunity includes 2 kV on power ports and 1 kV on signal ports per IEC 61000-4-4, severity level 3. That's a solid spec for industrial environments with motor starters and contactors banging around.
Carries ATEX approval PTB 06 ATEX 3001 Ex II (2) GD, meaning it's certified for use in potentially explosive atmospheres — category 2 for gases and dusts. That's a key differentiator if you're building for a hazardous-area line. Substance prohibitance date of 07/01/2006 aligns with RoHS compliance.