Redundant Power Sources

ztC Endurance systems require at least two separate and independent AC power sources—an A‐side power source and a B‐side power source—that provide power to the system's power receptacles. Either source must be capable of continuing to provide power if power to the other source is lost.

The A‐side power source provides power to the top power‐supply unit (PSU) in the system. The B‐side power source provides power to the bottom PSU.

Each PSU in the system is capable of providing power to the entire system. When both PSUs have electrical power, they share the load of the system components; however, if one PSU fails or if power is lost to either the A‐ or B‐side power source, the remaining PSU can pick up the full load of the system.

Although either PSU is capable of powering the ztC Endurance system, it is still important to separate power sources as much as possible to maximize redundancy. Furthermore, if you connect user‐supplied peripheral components that also contain two PSUs, attach each side to the independent A‐ and B‐side power sources. For components that do not require two sources of power, such as monitors, management PCs, or other user‐supplied components, you typically attach these components to the A‐side power source.

If provided by the customer, a pair of PDUs may supply power to multiple systems and components in a cabinet. The top PDU in the cabinet typically provides A‐side power. The bottom PDU typically provides B‐side power.