Part Overview and Key Ratings
The Siemens 3RB1246-1EM10 is a solid-state overload relay designed for full motor protection, covering a current range of 25 to 100 A. It operates on a 220-240 VAC control supply at 50/60 Hz and is sized for S2/S3 mounting, making it a direct fit for Siemens motor starter assemblies in that frame class. The 25-100 A adjustable current range, paired with a tripping class adjustable from 5 to 30, means this relay can be tuned to protect motors with different starting characteristics — from quick-starting pumps (class 10) to high-inertia loads like centrifuges or crushers (class 20 or 30). The solid-state sensing avoids the mechanical fatigue of bimetal relays, giving consistent trip performance over the device's life.
The relay mounts individually (not as a block set) and uses a screw-terminal aux circuit for the control wiring — standard for panel builds where the overload relay is wired back to a PLC input or a contactor coil. The 220-240 VAC control voltage means it integrates directly into a 230 V control transformer circuit without an intermediate relay or DC power supply.