Compaq AlphaServer GS60E Service Manual page 25

Three-phase AC power enters the system by cable through the AC input box
(see Figure 1-7). The H7506 power supplies convert three-phase AC power to 48
VDC. Three hot-swappable power supplies offer n+1 redundancy; that is, if any
one power supply fails, the remaining two supply the needed power.
Introduction 1-13