Square D DD250.0 Three-Phase Industrial Contactor With Overload Relay

The Square D DD250.0 is a melting-alloy thermal overload unit (Class 20) designed for use with Square D DD-series three‑phase motor starters. It provides overload protection for motor circuits via a melting alloy element that trips when current reaches 176–184 A. The unit is specified for 480 V systems and supports a maximum system voltage up to 600 V in standard motor‑control configurations. As part of the DD250.0 family, it is intended to be paired with DD-series contactors and magnetic motor starters to safeguard three‑phase motors in industrial control panels. This thermal overload unit serves as the overload component within a DD starter assembly, delivering reliable protection in applications where motors are subject to overcurrent conditions in three‑phase, four‑wire configurations.