Allen-Bradley 156-B20CB1 Programmable Logic Controller Module

The Allen-Bradley 156-B20CB1 is a solid‑state contactor used to switch AC loads in industrial control systems, delivering 20 A of load current in a compact, module‑style package that fits within the 156‑B series family. It supports a broad line‑voltage range of 24 to 480 VAC and accepts a DC control coil in the 5–24 V range, providing single‑phase switching for standard motor and heater control applications. As part of Rockwell Automation’s legacy 156‑B line, this model was discontinued on August 15, 2017, with the recommended direct replacement 156‑C1P20NCD for new installations or modernization projects. In practice, engineers choose this device in control panels and automation equipment when quiet operation, reduced wear compared with mechanical relays, and fast switching are advantageous, especially in environments where reliable AC load control is essential.