Cutler Hammer 9-1875-3 Size 6 Contactor: High Current Definite Purpose Contactor with 480V Coil

Product Overview

The Cutler Hammer 9-1875-3 is a Size 6 definite purpose contactor manufactured by Eaton Corporation under the Cutler Hammer brand. This contactor is designed for high-current switching applications, typically used in motor control centers, industrial machinery, HVAC systems, and lighting control panels. The device features a 480 V AC coil and is rated for continuous current handling consistent with NEMA Size 6 standards, making it suitable for controlling large motors or resistive loads in demanding environments. The contactor employs a solenoid-operated mechanism with silver-alloy contacts to ensure reliable make and break of power circuits, even under high inrush currents. The open-style construction allows for easy inspection and maintenance, while compact dimensions relative to its current rating enable efficient use of panel space.

Key Features of Cutler Hammer 9-1875-3

The Size 6 rating indicates that this contactor is capable of starting and stopping NEMA standard motors up to approximately 150 horsepower at 480 V, depending on the specific motor code and duty cycle. The contactor features three main power poles configured as normally open, with heavy-duty silver-alloy contacts that resist welding and erosion under high current conditions. The 480 V AC coil is designed for continuous duty operation and includes built-in transient suppression to protect the control circuit from voltage spikes generated when the coil is de-energized. The contactor mechanism includes an magnet frame and armature with low-friction bearings, providing consistent pickup and dropout voltages over millions of mechanical operations.

The 9-1875-3 incorporates an auxiliary contact block that provides one normally open and one normally closed contact for status indication or interlocking purposes. The main contacts are easily accessible for inspection and can be replaced if worn, extending the service life of the contactor. The unit is designed for panel mounting using through-panel screws, with clear marking of line and load terminals for proper wiring. The contactor is rated for AC-3 utilization category for motor starting applications, and AC-1 for resistive loads. The product complies with applicable UL, CSA, and IEC standards for industrial control equipment.

Technical Specifications

• Manufacturer: Cutler Hammer (Eaton Corporation)

• Part Number: 9-1875-3

• Contactor Size: NEMA Size 6

• Coil Voltage: 480 V AC, 60 Hz

• Number of Poles: 3 normally open main poles

• Auxiliary Contacts: 1 normally open + 1 normally closed

• Continuous Current Rating: Consistent with NEMA Size 6 (see manufacturer datasheet)

• Horsepower Rating at 480V: Approx. 150 HP (typical for Size 6)

• Utilization Category: AC-3 (motor starting), AC-1 (resistive)

• Contact Material: Silver-alloy

• Coil Duty: Continuous

• Coil Transient Suppression: Built-in

• Mounting: Panel mount, through-panel screws

• Terminal Type: Lug type for main wires, screw for auxiliaries

• Operating Temperature: -20 to +40 °C typical

• Certifications: UL Listed, CSA Certified

Functional Description

When control voltage of 480 V AC is applied to the coil terminals of the Cutler Hammer 9-1875-3 contactor, the magnetic field generated by the coil attracts the armature toward the magnet frame. This mechanical motion closes the main power contacts, completing the circuit between the line and load terminals. The auxiliary contacts simultaneously change state: the normally open contact closes, and the normally closed contact opens. When the coil is de-energized, a spring returns the armature to its rest position, opening the main contacts and restoring the auxiliary contacts to their normal states. The transient suppression device across the coil prevents high-voltage inductive kickback from damaging sensitive PLC outputs or relay contacts that control the contactor. The contactor can be mechanically latched if required using external hardware, though the standard version is electrically held. The silver-alloy contacts are designed to withstand the arc produced during switching, with arc chutes extending into the contact area to quench the arc rapidly and minimize contact erosion.

Applications

The Cutler Hammer 9-1875-3 Size 6 contactor is deployed in industrial applications requiring reliable switching of high-current circuits. Typical uses include motor starters for large pumps, compressors, and fans in manufacturing plants; lighting contactors for high-wattage industrial lighting systems; power switching for electric furnaces and ovens; and as a main disconnect or line contactor in heavy machinery. The contactor is also used in air conditioning and refrigeration systems for large commercial buildings, where it controls the compressor motors. For maintenance and electrical service providers, the 9-1875-3 provides a direct replacement for failed contactors in existing equipment, minimizing downtime. Panel builders specify this contactor when a NEMA Size 6 rating with a 480V coil is required for applications subject to the demanding start cycles typical of heavy industrial motors.