Allen-Bradley 810-A15C Series B Inverse Time Overload Relay

The 810-A15C is an inverse time relay from Allen-Bradley's Bulletin 810 line, designed for overload protection of AC and DC motors. The Series B version features improved thermal memory and ambient temperature compensation. The relay is adjustable over a current range of 1.5 to 15 A, making it suitable for small to medium-sized motors. It provides inverse time trip characteristic (Class 10, 20, or 30 selectable), meaning the trip time decreases as the current increases, closely matching motor heating curves.

Electrical Specifications

• Current Setting Range: 1.5 – 15 A (adjustable via dial)

• Trip Class: 10, 20, or 30 (selectable via DIP switch)

• Voltage Rating: 600 VAC max (or 250 VDC for DC applications)

• Contact Configuration: 1 N.O. (alarm) and 1 N.C. (trip) – both are mechanical contacts rated 5 A at 250 VAC

• Thermal Memory: Yes (retains thermal state after power-off for 15 minutes)

• Ambient Temperature Compensation: -20°C to +70°C

Features and Functions

The relay provides phase loss detection (for three-phase motors) and phase imbalance protection. It also includes a manual reset button (push) and an automatic reset option (selectable). An LED indicator shows trip status and power-on. The relay has a test function that simulates overload to verify the trip circuit. It also offers a remote reset capability via a separate terminal.

Physical and Environmental

Dimensions: 65 mm × 45 mm × 45 mm (H × W × D). Weight: 0.15 kg. Mounting: DIN rail or panel mount with screws. Operating temperature: -20°C to +70°C; storage: -40°C to +85°C. The relay is enclosed in a self-extinguishing plastic housing (UL 94 V-0) and rated for pollution degree 3. It is CE, UL, and CSA certified.

Compatibility

The 810-A15C is compatible with Allen-Bradley contactors (e.g., Bulletin 100-C, 100-D) via direct mount or separate mounting. It can be used with any motor starter that accepts a separate overload relay. The relay connects in series with the motor power circuit via its terminals.

Applications

Typical uses include protection of conveyor motors, pumps, fans, and compressors. The inverse time characteristic prevents nuisance tripping during normal starting currents while providing timely protection against sustained overloads.