Allen-Bradley 1746-P4 Power Supply Designed for SLC 500 modular control systems, the 1746-P4 supplies chassis backplane power and a separate 24V DC user-power output. Manufacturer Discontinued No Planned Direct Replacement Application & System Fit The 1746-P4 supports power distribution within an existing Allen-Bradley SLC 500 modular control system. Common sourcing triggers Power-supply fault indications, suspected loss of chassis power, unstable controller operation, or