When A Power Supply Fails - ProCurve 6200yl Management And Configuration Manual

Power Over Ethernet (PoE) Operation
Planning and Implementing a PoE Configuration
11-28
Therefore, you can power 17 ports at full power (273 watts - 17 watts = 256
watts ÷ 15.4 watts per port = 16.6 + 1 ports). In actual practice, the PD will
mostly likely use less than 15.4 watts of PoE power, allowing you to attach
more than 17 PDs.
For example, suppose you have 24 identical appliances to connect to a PoE
module receiving 273 watts of PoE power. For this example, each appliance
requires 8.5 watts to operate. In this case, the module would support 24
appliances at any given time because there is enough unused power to meet
the minimum of 17 watts required to support the initial power-up of the 24th
appliance. That is, 273 - (24 x 8.5) = 69 watts of unused power.

When a Power Supply Fails

You must have two power supplies installed to maintain at least some amount
of PoE power or to keep the switch itself operational if one power supply fails.
If you have two J812A power supplies installed supplying 273 watts of PoE
power each (total = 546 watts), then 273 watts of PoE power will be available
to continue supplying PoE power to ports in priority order if one supply fails.
If you have two J8713A power supplies installed supplying 900 watts of PoE
power each (total =1800 watts), then 900 watts of PoE power will be available
to continue supplying PoE power to ports in priority order if one power supply
fails.
If you have a mixed power supply configuration with one J8712A power supply
supplying 273 watts of PoE power, and one J8713A power supply supplying
900 watts of PoE power, a total of 1173 watts of PoE power is available. If a
power supply fails, the switch will continue to supply 273 watts of PoE power
to the ports with the highest priority (if all ports are the same priority level,
power is allocated to the lowest port number first) and power down any ports
using power above the total of 273 watts. The switch then determines which
power supply actually failed, the larger J8713A or the smaller J8712A. If the
smaller power supply failed, the switch restores power to the ports in priority
order until the available 900 watts is used.
If the larger J8713A power supply fails, then only 273 watts of PoE power is
available and the other ports remain shut down in priority order.
For additional information about planning your PoE configuration, refer to
the PoE Planning and Implementation Guide, which is available from the
ProCurve Networking web site at www.procurve.com. (Click on technical
support, then Product manuals (all).)