The Allen-Bradley W57 is a eutectic alloy thermal overload heater element engineered for use with motor starters, overload relays, and motor control equipment. Trip Class 20 operation makes it ideal for standard industrial duty cycles where reliable thermal protection is required.
Overview
The Allen-Bradley W57 is a replacement heater element for Bulletin 500 Line thermal overload relays. This Type W heater element provides Class 20 trip characteristics, which deliver consistent, predictable thermal protection suitable for general-purpose motor applications. The eutectic alloy construction ensures stable performance across typical industrial temperature ranges, making it a standard choice for motor control circuits requiring NEMA-rated protection.
Key Features
- Eutectic alloy construction for stable thermal response
- Class 20 trip rating—standard protection for general applications
- Current range: 15.3–18.5 amps across multiple starter sizes
- Manual reset type for operator-controlled overload clearing
- Direct fit for Bulletin 500 Line starters (Sizes 00–0, 1, 2)
- Authentic Allen-Bradley/Rockwell Automation component
Technical Specifications
- Current Rating (Size 00–0): 15.7 A
- Current Rating (Size 1): 16.3 A
- Current Rating (Size 2): 16.4 A
- Operating Range: 15.3–18.5 A
- Trip Class: 20
- Heater Type: Type W—Eutectic Alloy
- Reset: Manual
- Application: Thermal Overload Relay
- Standard: NEMA/KC Approved
- UPC: 00781180154379
Typical Applications
The Allen-Bradley W57 is commonly used in:
- Three-phase motor control circuits with magnetic starters
- NEMA-rated industrial motor protection systems
- General-purpose pump, fan, and compressor motor starters
- Equipment requiring Class 20 thermal overload protection
- Replacement maintenance for existing 500 Line starter systems
Compatibility & Replacements
Compatible With
- Allen-Bradley Bulletin 500 Line magnetic starters
- NEMA-rated motor starter enclosures
- Thermal overload relay units accepting Type W heater elements
- Standard three-phase motor control circuits (AC)
- Motor protection schemes requiring Class 20 trip characteristics
Replaces / Drop-In Replacement For
Verify compatibility with your system integrator before ordering. The W57 is a standard heater element for Bulletin 500 starters; cross-reference your existing overload relay model to confirm direct replacement eligibility.
Works With
- Allen-Bradley 500 Line overload relay contactors
- Type W eutectic-alloy thermal protection networks
- Manual and auto-reset control schemes
- NEMA-compliant motor protection architectures
