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The W77 thermal overload relay heater element from Allen Bradley is designed for effective protection in electrical systems. This eutectic alloy heater is rated for use with 600 V AC, primarily intended for continuous duty motors with a service factor equal to or greater than 1.15.
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Technical specifications for W77
| Manufacturer | Allen Bradley |
|---|---|
| Product Type | Thermal Overload Relay Heater Element |
| Product Line | Bulletin 500 Accessories |
| Part Number | W77 |
| Weight | 0.13 lbs (0.06 kg) |
| UPC | 781180512896 |
| Heater Element Type | W (Eutectic Alloy) |
| Trip Class | 20 |
| Size 00–0 Full Load Amperes (FLA) | 6.33 A |
| Size 1 Full Load Amperes (FLA) | 6.28 A |
| Rated Voltage Compatibility | 600 V AC |
| Relay Class Compliance | NEMA ICS 2, Part 4 |
| Overload Relay Type | Eutectic Alloy Overload Relay |
| Trip Time at 600% Rated Current (Class 20) | ≤ 20 seconds |
| Trip Time at 600% Rated Current (Class 10) | Not applicable (Type J only) |
| Trip Time at 600% Rated Current (Class 30) | Not applicable (Type WL only) |
| Motor Duty Compatibility | Continuous duty motors with service factor ≥ 1.15 |
| Controller Size Compatibility | Size 00, Size 0, Size 1 |
The Allen Bradley W77 is a thermal overload relay heater element, crafted for use within Bulletin 500 accessories. This heater element is part of the eutectic alloy type, designed specifically for reliability and quick response to overload scenarios. It comes with a Universal Product Code (UPC) of 781180512896.
Rated for a maximum voltage of 600 V AC, the W77 effectively meets the demands of various continuous duty motors that have a service factor of 1.15 or higher. In terms of current ratings, the device accommodates sizes 00 and 0 at 6.33 A and size 1 at 6.28 A under Full Load Amperes (FLA) specifications. This flexibility allows for a broad application range involving different motor sizes.
The trip classification is classified as Class 20, providing robust protection against overloads. When subjected to a rated current of 600%, the trip time is guaranteed to be ≤ 20 seconds, ensuring safety and system integrity in demanding operating conditions. Compliance with NEMA ICS 2, Part 4 establishes the W77 as an industry-standard component for overload relay applications. Additional trip class capacities for Class 10 and Class 30 are not applicable to this type, noting the specific design confines of Type J and Type WL respectively. Overall, the W77 element is engineered to provide efficient protection for compatible controllers sized 00, 0, and 1.