Siemens S30122-K5490-X-2 Power Supply Unit

Siemens S30122-K5490-X-2 Power Supply Unit is a Siemens Building Technologies ONAN power supply module identified by the part numbers S30122-K5490-X-2 and 3-70538-0000, indicating they refer to the same unit in Siemens’ legacy parts catalog. The S30122-K5490-X-2 designation appears in repair and procurement listings that reference a Siemens Building Technologies ONAN power supply 3-70538-0000. This unit is sold by multiple third‑party sellers as a replacement component for compatible Siemens equipment; listings exist on marketplaces such as eBay and various distributors offer refurbished units under this model. Because it is a dedicated Siemens part, it is typically used within Siemens building automation or HVAC control hardware that requires a dedicated power supply module. Buyers seeking this part should verify compatibility with their Siemens system by matching the exact model numbers S30122-K5490-X-2 or 3-70538-0000 to their equipment catalog.