GT400S400A is a bimetallic thermal overload relay designed to protect AC circuits and motors against overloads, phase failure, long starting times, and prolonged stalling. This 400AF contactor-mounted relay features a setting range of 260–400A with Class 10 differential protection and screw clamp terminals. The relay operates at rated voltages up to 690V with a 6kV impulse withstand capability, IP 20 enclosure rating, and temperature range of -5°C to +40°C. It includes auxiliary contacts (1NO+1NC), a trip indicator, stop/test button, and manual/automatic reset selector for flexible motor protection in industrial applications.