Allen-Bradley 810-A22A Inverse Time Delay Relay

The Allen-Bradley 810-A22A Inverse Time Current Relay is an open-type timing relay in the Bulletin 810 family that provides inverse-time overcurrent protection for industrial circuits. It uses a timing mechanism powered by a coil that draws 162 A, and its time delay is the inverse function of the fault current, allowing coordination with faster protection devices. The A22A variant sets the trip threshold from 98 to 279 A, enabling adjustment to match motor and feeder protection schemes. The relay timing is provided by a dashpot mechanism, a hallmark of the classic 810 series, and this version is part of the same family as the companion B22A for the enclosed variant. Typical applications include motor protection, feeder protection, and general overcurrent protection in AC circuits where selectivity is important; it is designed to trip when current exceeds the set point and then hold off until the inverse-time curve allows, helping prevent nuisance trips while still isolating faults. This model’s identity as a 162 A coil-current variant with a 98–279 A adjustable trip range aligns with the established 810-A series characteristics used historically in industrial control panels and protection schemes.