HAT903ASAC120 is a heavy-duty electromechanical relay from the HAT-900 series designed for high-current switching applications. The relay features SPDT (Single Pole Double Throw) contact configuration with 40A normally open and 20A normally closed contact ratings, utilizing silver cadmium oxide contacts with copper base for reliable performance. It operates with a DC coil and is sealed for wave soldering and washing, enabling integration into automated assembly lines. The relay maintains contact resistance of 20 mO maximum at initial value, with insulation resistance of 10 MO minimum at 500 VDC and dielectric strength of 2000 VAC between contact and coil, frame and contact, and coil and frame. Operating temperature range spans from -40°C to 85°C (Class B) or -40°C to 105°C (Class F), with pull-in voltage at 75% of nominal and drop-out voltage at 10% of nominal at 25°C. This relay is ideal for industrial control, power distribution, and switching applications requiring sealed construction and high current capacity.