HP ProCurve zl Series Planning And Implementation Manual page 33

Figure 4-5. Example of a 5406zl with two power supplies (J8712A and J8713A)
In this example there is one J8712A and one J8713A power supply supplying
1173 watts for PoE usage. This configuration offers 136 ports of which all can
be powered at 7.0 watts each, and offers eight ports for fiber optic gigabit
connectivity. ProCurve Networking highly recommends that the two types of
power supplies are not mixed in the same 5406zl chassis.
Source of Power Watts Available # of Ports Powered and Average Watts/
Two Internal PoE 1173 (without
Power Supplies: redundancy)
one J8712A
one J8713A
Or, one power supply (J8712A) could be used to supply PoE power at 273 watts
and the other power supply (J8713A) could be used as a secondary power
supply. If both power supplies are connected to different power sources, one
could backup the other in case of failure. However, if the J8713A power supply
fails, the J8712A can keep the switch running but cannot supply all the PoE
power that the J8713A was supplying. Therefore you need to plan very
carefully when using this configuration.
In a system with mixed power supplies, failover is calculated based on the
largest power supply failing. If it turns out to be the smaller power supply that
fails, some of the ports that were powered off during the power failure will
come back on. For example, in figure 4-5 there is mixed power supplies
offering 900 W+ 273 W for 1173 W total. Failover power will be calculated at
273 W, so if a power supply fails all the controllers will fall back to a power
level that can be supported by 273 W. If it turns out the 273 W supply failed,
the system will detect that during the power supply polling cycle and increase
power back up to 900 W total. This would result in some load coming back on
if the total power used by all the loads in the box was greater than 273 W.
Front
Port
• 76 @ average 15.4 W each
• 136 @ average 7.0 W each
• 136 @ average 4.0 W each
Planning and Implementation for the Series 5400zl Switch
Planning Your PoE Configuration
273 Watts
for PoE
Power Supply
J8712A
Redundant # of Ports Powered and
Average Watts/Port
• 17 @ average 15.4 W
• 39 @ average 7.0 W each
• 68 @ average 4.0 W each
900 Watts
for PoE
Power Supply
J8713A
4-9