Siemens 500-650217 PAD-4 Main Board Assembly

Siemens 500-650217 PAD-4 Main Board Assembly is the PAD-unit main board (PAD-4-MB) that serves as the central NAC power-supply interface inside Siemens PAD-4 distributed power units used for fire alarm systems. Designed to fit inside the PAD-4 unit enclosure (500-050081), it mounts in the enclosure via four bottom mounting holes, secured with four screws during installation. The board is designed to work with Siemens FP-series power supplies, specifically FP2011-U1 (170 W) or FP2012-U1 (300 W), enabling scalable NAC power distribution to notification appliances and NAC expanders as needed. Siemens documents label this component as the PAD-4 NAC Power Supply Main Board, and the PAD-4 data sheets include diagrams showing the general layout of the main board. Official configurations include the 6A PAD-4 kit, which comprises the PAD-4 enclosure, the PAD-4 main board, and a 170 W power supply, with other kits offering additional power options and accessories such as the Class A adapter card (PAD-4 CLSA) for expanded compatibility. In practice, the PAD-4 main board forms the backbone of the PAD-4 system’s NAC power distribution within Desigo Fire Safety installations, supporting expansion via NAC extenders and compatible adapters as described in Siemens documentation. When paired with the enclosure and the appropriate power supply, the PAD-4 Main Board Assembly provides reliable interface and power delivery to notification devices across the building’s fire alarm network.