Overview
The Siemens 3UA5400-1J overload relay is a field-proven, solid-state thermal protection device designed for Class 2 motor overload control in three-phase AC systems. This relay functions as an integral component within 3TF and 3TB contactor assemblies, automatically disconnecting circuits when motor current exceeds the adjustable setpoint. Built to handle industrial duty cycles, the 3UA5400-1J combines thermal compensation with electronic sensing to deliver consistent, repetitive motor protection.
Key Features
- Solid-state design: Electronic sensing element eliminates mechanical wear, reducing nuisance trips and improving response accuracy.
- Adjustable current range: 6.3–10A allows precise matching to specific motor sizes and load profiles without relay substitution.
- Thermal compensation: Ambient temperature-corrected response maintains consistent protection performance across seasonal operating conditions.
- 3TF/3TB contactor compatibility: Direct integration with Siemens three-phase starters simplifies installation and reduces wiring complexity.
- Dual-pole switching output: 1 NO + 1 NC contacts enable both trip signaling and downstream logic integration.
- 600V AC rated: Suitable for single-phase and three-phase motor circuits up to 600V systems.
Technical Specifications
This relay delivers precise overload protection in demanding industrial environments where motor uptime is critical. Thermal response is calibrated for Class 2 (5–8 second) trip time at 150% rated current, consistent with IEC 60947-4-1 overload relay standards.
Typical Applications
- Three-phase fan and pump motor protection in HVAC and process systems
- Machine tool spindle motor overload control in manufacturing environments
- Conveyor system motor protection in material handling and logistics operations
- Compressor motor safeguarding in industrial pneumatic and refrigeration circuits
- Circulating pump protection in chilled water and hot water distribution systems
- General-purpose industrial motor starter assemblies requiring certified overload protection
Compatibility & Replacements
The 3UA5400-1J pairs seamlessly with Siemens 3TF44 and 3TB44 series contactor units. Direct mechanical and electrical alignment ensures plug-and-play installation without secondary mounting hardware. This model also appears as 3UA54-00-1J in legacy and international documentation. If upgrading larger motor circuits, consider the higher-amperage 3UA5600-1J (10–16A) or 3UA5800-1J (16–25A). For drop-in replacement eligibility in existing 3TF starter assemblies, verify contactor model and terminal layout before substitution.
