Overview
The Allen-Bradley W64 overload relay heater element is a precision-engineered NEMA thermal component designed for reliable overload protection in motor control applications. Built with eutectic alloy construction, the W64 delivers consistent Class 20 trip performance across ambient temperature variations and is the industry-standard choice for general-purpose AC motor protection in industrial automation systems.
Key Features
- Current Rating: 27.2–36.9 A nominal full-load amperes
- Eutectic Alloy Construction: Proven thermal solder technology ensures predictable melt characteristics and reliable trip points
- Class 20 Trip Performance: Meets NEMA ICS 2-222 standard; trips in 20 seconds or less at 600% of rated current
- Manual Reset: Required operator intervention ensures controlled restart and prevents nuisance tripping
- Bulletin 500 Compatibility: Direct replacement for Allen-Bradley Bulletin 500 line starters, Sizes 0–3
- Temperature-Compensated Design: Inherent ambient temperature compensation protects motors whether controller and motor are at same or different ambient temperatures
Technical Specifications
The W64 heater element is engineered to precise thermal tolerances. Key operating characteristics include manual reset action, eutectic alloy thermal sensor, and NEMA standardization for integration into Bulletin 500 motor starters, Size 0 (28.5 A), Size 1 (30.0 A), Size 2 (30.5 A), and Size 3 (33.5 A) frames.
Typical Applications
- General Motor Protection: Three-phase AC squirrel-cage induction motors in continuous or intermittent duty
- Industrial Motor Starters: Thermal overload element in Bulletin 500 magnetic motor starters
- Pump & Fan Motors: Centrifugal and axial-flow equipment in HVAC and water-handling systems
- Machine Tool Motors: Lathe, mill, and drill press drive motors requiring reliable thermal protection
- Standard Ambient Installations: Motors and controllers at similar temperatures (±10 °C difference)
Compatibility & Replacements
Compatible With
- Allen-Bradley Bulletin 500 Line Motor Starters (all sizes)
- Type W thermal overload relay assemblies
- NEMA-compliant thermal overload protection circuits
- AC motor control systems using eutectic alloy trip elements
- Manual and magnetic motor starters with thermal overload coils
Replaces / Drop-In Replacement For
The W64 is the standard Type W heater element for Bulletin 500 motor starters rated in the 27.2–36.9 A range. Verify the full-load amperage (FLA) of your motor nameplate and ambient temperature conditions at both controller and motor locations before ordering. If motor FLA falls between two heater element ratings, consult Allen-Bradley selection tables or your system integrator to confirm the correct element size.
Works With
- Type W heater element thermal overload relays
- Manual reset mechanisms in Bulletin 500 starters
- Three-phase AC power systems (standard industrial 208V, 240V, 460V, 575V)
- NEMA Class 20 overload protection standard
- Temperature-compensated motor protection circuits
