Overview
The Allen-Bradley W57 overload relay heater element is a eutectic alloy thermal unit designed for Bulletin 500 line starters and motor control circuits. Manufactured by Rockwell Automation, this component delivers reliable overload protection per NEMA standards for industrial automation, manufacturing, and electrical control systems. The Type W heater element provides Class 20 operation, making it suitable for general applications across a wide range of motor sizes and duty cycles.
Key Features
- Eutectic alloy construction for consistent thermal response and trip characteristics
- Class 20 trip rating for standard industrial motor protection
- Manual reset type overload relay element
- Compatible with Bulletin 500 line magnetic starters and NEMA motor controls
- Current range: 15.3–18.5 amps across multiple starter sizes
- KC standard designation; NEMA-approved for U.S. industrial use
Technical Specifications
- Heater Type: Eutectic Alloy Overload Relay Element
- Rated Current Range: 15.3–18.5 Amps
- Trip Class: 20 (standard)
- Size Ratings: Available for Sizes 00–0 (FLA 15.7A), Size 1 (FLA 16.3A), Size 2 (FLA 16.4A)
- Reset Type: Manual
- Standard: KC (NEMA)
- Product Type: Thermal Unit Heating Element
- UPC: 781180154379
- Manufacturer: Allen-Bradley / Rockwell Automation
Typical Applications
- Three-phase induction motor protection on Bulletin 500 line starters
- Industrial automation and control circuits requiring thermal overload protection
- NEMA-compliant motor control panels and MCC (Motor Control Centers)
- Magnetic motor starter circuits in manufacturing and facility automation
- Replacement heater elements for existing W Series overload relay assemblies
Compatibility & Replacements
Compatible With
- Allen-Bradley Bulletin 500 line starters and magnetic motor controls
- NEMA-rated motor control systems and starter assemblies
- Type W overload relay mechanisms and thermal units
- Industrial motor protection circuits rated 15–18 amps
Replaces / Drop-In Replacement For
- Original equipment W57 heater elements in existing Bulletin 500 assemblies
- Worn or tripped thermal units requiring replacement
- Verify compatibility with your specific starter model before ordering
Works With
- Allen-Bradley magnetic motor starters (Bulletin 500)
- NEMA motor control enclosures and panels
- Standard three-phase motor protection schemes
- Manual and automatic starter circuits
