Overview
The Siemens 3UA52-00-2C thermal overload relay is a compact, adjustable bimetal-element protection device designed for three-phase AC motor circuits. Rated 16–25A and Class 10 (10-second trip at 7.2× rated current), this relay provides reliable overload and phase-failure protection. Its ambient-compensated design ensures accurate operation across temperature variations, making it suitable for harsh industrial and marine environments.
Key Features
- Adjustable current range: 16–25A with smooth calibration
- Class 10 thermal overload characteristic for rapid fault response
- Ambient temperature compensation for stable performance
- Dual auxiliary contacts: 1 NO + 1 NC (B600/R300 category)
- Voltage ratings: 690V UI, 415V UI (IEC 947 compliant)
- Manual or automatic reset options available
- Bimetal construction: proven reliability in demanding applications
Technical Specifications
- Current Rating: 16–25A (adjustable)
- Trip Class: Class 10 (IEC 60947-4-1)
- Voltage Rating: 690V UI / 415V UI
- Auxiliary Contacts: 1 NO + 1 NC, rated B600/R300
- Temperature Compensation: Ambient compensated, operates above 150V
- Tripping Current: 125% of rated current (standard)
- Torque: 9–13 Lb-In (1–1.5 Nm)
- Weight: 180g
- Standards: IEC 947, IS 13947, VDE 0660
- Origin: Made in Germany
Typical Applications
- Three-phase AC motor overload protection (0.1–400A range across 3UA series)
- Industrial pump and fan motors
- Marine and offshore equipment
- Contactor-mounted or standalone protective relay in motor starter circuits
- Phase-failure detection in critical industrial systems
Compatibility & Replacements
The Siemens 3UA52-00-2C is designed to mount directly on compatible Siemens 3TF34/35 and similar contactor frames. The 3UA series remains widely supported despite advancing toward modern digital protection; many engineers continue to specify it for retrofit and legacy system maintenance. Always verify contactor mounting base compatibility before ordering. This unit arrives in used condition—inspect for physical damage and confirm calibration if critical trip accuracy is required.
