🔹 Siemens Thermal Overload Relay – 3UA55002D (3UA Series, Variant D)
The Siemens 3UA55002D 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 excessive motor current heats the bimetal strip, causing it to bend and trip the relay, thereby disconnecting the motor supply to prevent damage.
This relay is used in combination with Siemens contactors in motor starter assemblies, providing reliable and economical motor protection in industrial environments. It helps prevent overheating, insulation failure, and unexpected motor breakdowns caused by electrical faults.
The 3UA55002D is typically used in the 20–32 A current setting range, making it suitable for medium-to-heavy duty industrial motors in applications such as pumps, compressors, conveyors, HVAC systems, and automation systems.
• Genuine Siemens 3UA Series thermal overload relay
• Model Number: 3UA55002D
• Bimetallic overload protection system
• Adjustable current range (20–32 A)
• Protection against overload and phase failure
• Trip-free mechanism for safety
• Temperature compensated operation for stable performance
• Suitable for three-phase motor protection
• Contactor-mounted compact design
• High reliability for industrial applications
| Parameter | Specification |
|---|---|
| Product Series | Siemens 3UA Series |
| Model Number | 3UA55002D |
| Product Type | Thermal Overload Relay |
| Protection Type | Overload + Phase Failure Protection |
| Operating Principle | Bimetal Thermal Mechanism |
| Current Range | 20 – 32 A |
| Mounting Type | Contactor Mounted / Plug-in |
| Application | Motor Protection |
| Compatible Contactors | Typically Siemens 3TF40 / 3TF41 / 3TF50 series (range dependent) |
| Brand | Siemens |
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