Allen-Bradley 810-A04B Magnetic Overload Relay

Allen-Bradley 810-A04B Magnetic Overload Relay is a Bulletin 810 electromagnetic motor-protection device designed to guard motors within control circuits. It delivers inverse-time overload protection by monitoring motor current and tripping the linked contactor when the current exceeds a preset threshold for a short interval, helping prevent overheating and potential damage from stalls or overloads. The 810-A04B variant is documented with a 6 A rating, indicating its nominal load-current characteristic within typical motor-start circuits and its coordination with standard Allen-Bradley contactors. This relay is intended for use with Bulletin 810 motor starters, and it is commonly applied in conveyors, pumps, fans, and machine tools where reliable, straightforward motor protection is essential. As part of the traditional 810 family, the 810-A04B supports rugged performance in industrial environments and integrates with standard control panels that rely on magnetic overload protection for economical, low-maintenance operation. When paired with a compatible contactor, the MOR provides predictable trip behavior to minimize downtime while preserving normal startup sequences under safe electrical conditions.