The 4NK0AS is an "Orange Line" thermal overload relay designed to protect motors and electrical circuits from overload conditions. It features a 1NO+1NC alarm contact with automatic reset capability, a built-in heater for accurate operation, and a calibrated rated current dial for precise adjustment. The relay includes a manual trip device and open-phase protection to detect phase loss conditions, with ambient temperature compensation that limits ampere value changes to approximately 10% between -5°C and 40°C. The alarm contact is rated for continuous operation at 2.5 A with current-make/break ratings of 15/1.5 A at 110-120V, 7.5/0.75 A at 220-240V, 3.75/0.375 A at 440-480V, and 3.0/0.3 A at 550-600V. This relay is ideal for industrial motor protection applications requiring reliable overload detection and automatic or manual reset functionality.