Siemens 3UA5500-2D Relay

Siemens 3UA5500-2D is a Sirius family thermal overload relay designed to protect small to medium motors by monitoring current and temperature and tripping to prevent winding damage. It mounts on Siemens 3TF-series contactors and offers a 20 to 32 A current setting range, with a manual reset option for controlled fault clearance. The unit includes a 1 normally open and 1 normally closed auxiliary contact to coordinate control logic in the motor circuit. Classified as a Class 10 thermal overload relay, the 3UA5500-2D is compatible with Siemens 3TF34/35 and 44/45 contactors and is typically used in motor control panels to guard against overload and phase imbalance conditions, extending motor life and improving protection of downstream equipment.