Square D A1.75 Contactor Thermal Overload Unit

Product Description

The SQUARE D A1.75 is a thermal overload unit designed as an accessory for compatible contactors used in motor control and electrical distribution applications. Thermal units sense heat generated by current flow through a bimetallic element, tripping the overload relay when sustained overcurrent conditions are detected. This protects motors and downstream equipment from damage caused by overloads or single-phasing events. The A1.75 is a compact, single-package component intended for installation by licensed electricians or qualified industrial maintenance technicians during contactor assembly or field service of motor control centers and panel-mounted starters.

Thermal units like the A1.75 are used in residential, commercial, and light industrial motor control applications wherever a contactor-based starter requires overload protection. Typical installations include HVAC compressor starters, pump motor panels, conveyor controls, and other fractional to integral horsepower motor circuits. The unit snaps or inserts into the overload relay block mounted on a compatible SQUARE D contactor, allowing field selection of the appropriate heater element for the motor full-load amperage rating.

Key Features

• Thermal overload sensing protects motors from sustained overcurrent and single-phase conditions
• Compact form factor fits within standard contactor overload relay blocks
• Single-unit package quantity supports exact replacement without excess inventory
• Bimetallic thermal element provides reliable trip response proportional to heat buildup
• OEM-style replacement maintains original contactor protection performance

Compatibility

Designed as an OEM-style replacement thermal unit for use with compatible SQUARE D contactor overload relay assemblies. Verify the specific heater element series and amperage range against the motor nameplate full-load amps and the contactor overload relay specifications before installation.

Installation Notes

Installation should be performed by a licensed electrician in accordance with the National Electrical Code (NEC) and applicable local codes. De-energize and lock out the circuit at the disconnect or breaker before accessing the contactor or overload relay block. Confirm the thermal unit amperage designation matches the motor full-load amperage rating as specified on the motor nameplate and the overload relay selection chart. Do not energize the circuit until the overload relay cover is fully seated and all conductors are properly terminated.