The BPAs support 2- or 4-line cords with a single universal type of 3-phase 200 - 480 V AC. The power supply units convert the regulated high-voltage DC power (supplied by BPA) to DC  power that is used as input for the Points of Load (POLs) in the CPC drawer and the PCIe+  I/O drawers. The power requirements depend on the number of CPC drawers (1 - 5), number of PCIe I/O  drawers (0 - 11), and I/O features that are installed in the PCIe+ I/O drawers. A schematic view of a maximum configured system with BPA power is shown in Figure 2-31. Each BPA installed requires a customer supplied power feed. The number of power cords that  are required depends on the system configuration. The total loss of one BPA has no effect on  system operation. Note:  For initial installation, all power sources are required to run the system checkout  diagnostics successfully. BPAs are installed in pairs 2 or 4 depending on the configuration. Consider the following  points: GLYPH<SM590000> BPA1 and BPA2 are always installed initially in Frame A GLYPH<SM590000> BPA3 and BPA4 are installed to support more components for larger configurations (CPC  and I/O drawers) GLYPH<SM590000> BPA1/BPA2 and BPA3/BPA4 for paired redundancy GLYPH<SM590000> From the rear of the system, the odd-numbered BPAs are above the even-numbered BPAs  in both frames GLYPH<SM590000> The total loss of one BPA in a pair has no effect on system operation Chapter 2. Central processor complex hardware components  79 Figure 2-31 Rear view- maximum configured system BPA power