🔹 Siemens Thermal Overload Relay – 3UA55002B (3UA Series, Variant B)
The Siemens 3UA55002B is a thermal overload relay from the 3UA Series designed to protect three-phase induction motors from overload, phase failure, and sustained overcurrent conditions. It operates using a bimetallic thermal mechanism, where motor current heats a bimetal strip; if the current exceeds the set limit for a defined time, the strip bends and trips the relay, disconnecting the motor.
This relay is used with Siemens contactors in motor starter assemblies, ensuring safe and reliable motor protection in industrial applications. It helps prevent overheating, insulation damage, and unexpected motor failure caused by electrical faults.
The 3UA55002B typically corresponds to the 12.5–20 A current setting range, making it suitable for medium-duty industrial motors used in pumps, compressors, conveyors, HVAC systems, and automation panels.
• Genuine Siemens 3UA Series thermal overload relay
• Model Number: 3UA55002B
• Bimetallic overload protection system
• Adjustable current range (12.5–20 A)
• Protection against overload and phase failure
• Trip-free mechanism for safety
• Temperature compensated for stable performance
• Suitable for three-phase motor protection
• Contactor-mounted compact design
• High reliability for industrial duty cycles
| Parameter | Specification |
|---|---|
| Product Series | Siemens 3UA Series |
| Model Number | 3UA55002B |
| Product Type | Thermal Overload Relay |
| Protection Type | Overload + Phase Failure Protection |
| Operating Principle | Bimetal Thermal Mechanism |
| Current Range | 12.5 – 20 A |
| Mounting Type | Contactor Mounted / Plug-in |
| Application | Motor Protection |
| Compatible Contactors | Typically Siemens 3TF40 / 3TF41 / 3TF50 (range dependent) |
| Brand | Siemens |
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