Hitachi COMPUTE BLADE 500 SERIES Management Module Setup Manual page 248

The power supply expansion function protects the power facilities, such as
circuit breakers and power distribution units (PDU), and power supply
modules in the system unit from the power overload beyond the allowable
value by the high speed power capping on the server blades. Power supply
module that is power receiving performance improved is adopted to realize
the power supply expansion function.
Disabled power supply expansion
Normal operation of redundant power supply
(Maximum supply power: 4200W)
Failure of redundant power supply
(Maximum supply power: 4200W)
2-224
Hitachi Compute Blade 500 Series Management Module Setup Guide
Functional detail