Siemens 3UA5400-2B is a three-pole thermal overload relay designed for motor protection when mounted on Siemens contactors, with a current setting range of 12.5 to 20 A and a voltage rating of 660 V. The device provides thermal-delay protection and includes a 1 NO + 1 NC auxiliary contact for feedback to control circuits. Part of the 3UA family (also listed as 3UA54 00-2B), it is commonly used with Siemens contactors in motor control circuits, including models in the 3TF32/3TF33 series, to monitor current and trip on overload.
