User's Manual

248 Power Management
belongs to a different AC power grid and must be cabled as such for proper
AC Redundant mode of operation. The load is shared across all active PSUs.
The load on a single PSU never exceeds 50 percent of its capacity.
With AC redundancy, the system can tolerate the loss of an entire AC power
grid or up to 50 percent of its capacity with failures of individual PSUs. The
system continues to supply adequate power to the modular enclosure system.
The AC Redundancy mode is the factory-default setting for 6 PSU
configuration and indicates the chassis is configured for AC Redundancy.
NOTE: A system will operate in an AC Redundant mode only if the required
conditions have been met. Specifically, each AC power grid must be populated with
matched PSUs and the overall load must not exceed the capacity of a single grid.
AC Redundancy Levels
CMC supports three levels of N+N AC Redundancy—1+1, 2+2, and 3+3.
In AC redundancy, the CMC reports all active power supplies as online. This
is done to ensure that the system does not experience downtime in the event
of a power failure to a grid. If any of the N PSUs in a grid fail, the CMC
reports the Enclosure Redundancy Status as No Redundancy. E-mail and/or
SNMP alerts are sent to administrators if you have configured the
Redundancy Lost event for alerting.
• 1+1 AC Redundancy Level — at least one PSU is connected to
each AC grid.
Figure 8-1. 1+1 Redundancy Level
Power
Supply
#1
Empty
Slot
#2
Empty
Slot
#3
Power
Supply
#4
Empty
Slot
#5
Empty
Slot
#6
AC Power Grid #1
AC Power Grid #2
Chassis DC Power Bus