Overview
The Allen-Bradley W57 thermal overload relay heater element is a Type W eutectic alloy overload protection device designed for Rockwell Automation’s Bulletin 500 Line starters. It provides Class 20 operation with full load amp ratings of 15.7A (Size 00-0), 16.3A (Size 1), and 16.4A (Size 2). This is a direct thermal sensing element that protects motors from sustained overcurrent conditions without requiring external power.
Key Features
- Eutectic alloy construction for reliable thermal sensing
- Class 20 operation recommended for general applications
- Manual reset type with KC standard certification
- Compatible with multiple Bulletin 500 starter sizes (00-0, 1, 2)
- Proven legacy heater element design with wide installation base
- Compact form factor fits standard overload relay cartridges
Technical Specifications
- Part Number: W57
- Manufacturer: Allen-Bradley / Rockwell Automation
- Type: Heater Element (eutectic alloy thermal)
- Trip Class: 20
- Reset Type: Manual
- Full Load Amps (Size 00-0): 15.7A
- Full Load Amps (Size 1): 16.3A
- Full Load Amps (Size 2): 16.4A
- Standard: KC (NEMA)
- UPC: 781180154379
Typical Applications
The W57 is used for thermal overload relays, magnetic motor starters and motor controls. Common applications include:
- Bulletin 500/509 line starters for three-phase motors
- Bulletin 592 overload relays protecting 15.3–18.5A motors
- NEMA-style motor protection in industrial control systems
- General-duty manufacturing, HVAC, and facility automation
Compatibility & Replacements
Compatible With
- Bulletin 500 Line starters (Sizes 00-0, 1, 2)
- Bulletin 509 magnetic starters
- Bulletin 592 overload relays
- NEMA Class 20 motor protection circuits
- Allen-Bradley 500 series control systems
Replaces / Drop-In Replacement For
- Original equipment W57 heater elements in Bulletin 500/509 starters
- Legacy thermal overload protection cartridges rated for 15.3–18.5A
- Used as direct replacement in existing Bulletin 500 installations
Works With
- Manual reset overload relay frames and bases
- Thermal sensing circuits (no software or networking required)
- AC motor protection circuits rated 15–20A full load
- Standard NEMA 500 line motor starter enclosures
