Siemens 48ATC3S00 ESP200 Electronic Overload Relay

Siemens ESP200 48ATC3S00 solid-state overload relay, part model 3UB8123-4CW2, delivers precise electronic motor protection for three‑phase motors in the 3 to 12 A range. Designed for use with Siemens starters, this unit can be mounted directly to a compatible contactor or operated as a stand‑alone device, and features main‑circuit windows to route motor leads while measuring current. The relay supports selectable trip classes in the 5–30 range (Class 5...30) for flexible protection, with a Size A1 frame and a 3‑phase configuration. The auxiliary circuit uses screw terminals, and the reset can be performed manually or automatically, enabling seamless integration into automatic protection schemes. As part of the ESP200 family, it provides solid‑state overload protection rather than traditional thermal devices, offering faster response and consistent performance in demanding industrial environments. Applications include conveyors, pumps, fans, and other three‑phase motor drives where compact protection, reliable shutdown, and straightforward integration with Siemens motor‑control components are important.