Siemens 3UA5400-2B Overload Relay

Siemens 3UA5400-2B overload relay is a thermal-delayed protection device for 3‑phase motor starters, designed to mount with Siemens contactors in motor-control circuits. It covers a current-setting range of 12.5 to 20 A, providing automatic protection for motors against overheating while the starter remains energized. As part of the 3UA54 family, the relay is used to safeguard industrial motors in applications such as conveyors, pumps, fans, and machine tools, helping prevent damage from overload conditions by interrupting the motor circuit when overheating is detected. The 3UA5400-2B variant is a compact, mounting-friendly unit intended for integration into Siemens starter assemblies, delivering reliable motor protection within its rated current window and compatible with typical Siemens motor-control layouts.