257150 - Miller 60A 3-Pole Contactor with 120V Coil

Technical Overview of the Miller 257150 Contactor

The Miller 257150 is a Definite Purpose (DP) contactor engineered specifically for the rigorous demands of industrial equipment, including heavy-duty welding power sources. As an electromechanical switch, this component is critical for managing the high-current power supply to the transformer or inverter stages of the machine. It features a 60 Ampere inductive load rating, making it suitable for medium-to-heavy industrial applications where reliable load breaking and making are essential.

This unit utilizes a 3-Pole configuration, allowing it to simultaneously switch three separate power lines. This is particularly common in three-phase power input systems or for isolating multiple circuit legs within a single-phase system. The contactor is actuated by a 120 VAC coil, which integrates seamlessly with standard 110V/120V control circuits found in most North American industrial machinery. The magnetic coil, when energized, pulls the contacts closed to complete the circuit, and releases them when de-energized to cut power.

A key feature of the Miller 257150 is its termination style. It is equipped with Box Lugs, which provide a superior mechanical and electrical connection compared to standard screw terminals or spade connectors. Box lugs allow for the insertion of stripped wire ends directly into the lug, where they are clamped down by a set screw. This ensures a high-pressure contact area that minimizes resistance and heat generation, a critical factor when handling 60 amps of current. The device is housed in a durable casing designed to resist the vibration and thermal cycling common in welding environments.

Technicians replacing this part should verify the control voltage matches the 120 VAC specification to prevent coil burnout or failure to actuate. As a genuine Miller Electric component, it meets strict manufacturing tolerances, ensuring it fits the mounting footprint and electrical characteristics required by the host machine without modification.