This power supply system is comprised of up to five rugged, industrial quality AC-DC plug-in modules. It uses field-proven topology with a track record in numerous applications to generate the required output power. Each module has a built-in redundancy diode that allows for an unlimited number of units to be paralleled for higher output power and N+1 redundant operation. The built-in redundancy also allows battery connection to the output for back-up purposes. The modules are hot insertable. Modules with different outputs can be combined into one shelf to create a multi-output system. The plug-in modules are cooled by natural air convection. Heat generating components are installed on an aluminum heatsink block that are connected to a large heatsink on the side of each module. This also provides exceptional mechanical ruggedness. The input and output are filtered for low noise. Full electronic protection, low component count, large design headroom, and the exclusive use of components with established reliability contribute to a high MTBF. The system is manufactured at our plant under strict quality control.