Overview
The Allen-Bradley W66 is a Type W eutectic alloy heater element designed for thermal overload relays and magnetic motor starters in industrial automation and control applications. This heater element is used in Bulletin 500 line starters with Trip Class 20 operation, and is recommended for general applications. The W66 provides proven, cost-effective motor protection across a wide range of motor sizes and operating conditions.
Key Features
- Current rating of 35.5–43 Amps
- Eutectic alloy type overload relay construction
- Class 20 operation for standard industrial motor protection
- Suitable for Bulletin 100/500/609/1200 starters and overload relays
- Manual reset type
- Meets CCC and KC standards
Technical Specifications
The W66 is rated for Size 1 (34.0 Full Load Amps), Size 2 (35.5 FLA), Size 3 (40.0 FLA), and Size 4 (43.0 FLA) applications. Class 20 overload relays trip in 20 seconds or less at 600 percent of rated current, making this element suitable for motors with standard starting characteristics. The heater element operates at ambient temperatures consistent with NEMA standards for indoor industrial control enclosures.
Typical Applications
- 3-phase AC motor protection in industrial manufacturing
- Squirrel cage induction motor overload protection
- Magnetic motor starter thermal backup protection
- General industrial automation and conveyor systems
- HVAC and pump motor control systems
- Factory automation and process control equipment
Compatibility & Replacements
Compatible With
- Allen-Bradley Bulletin 500 motor starters
- Allen-Bradley Bulletin 100 starters
- Allen-Bradley Bulletin 609 motor control components
- Allen-Bradley Bulletin 1200 starters
- Standard NEMA Type W overload relay housings
- Class 20 thermal overload relay bases
Replaces / Drop-In Replacement For
The W66 is positioned in the thermal overload heater element selection table between the W64 and W67. It directly replaces OEM part W66 heater elements in any Bulletin 500/100/609/1200 starter requiring a 32–43 AMP thermal overload element. Engineers selecting overload protection for motors in the 35–43 AMP range should reference the applicable motor full load amperage against the Allen-Bradley heater element selection table.
Works With
- Manual and magnetic motor starters
- Thermal overload relay bases (all standard NEMA frames)
- Electronic overload relays as backup thermal protection
- Standard three-phase AC power distribution systems
- Industrial control circuits and PLC-based motor control systems
