EPS 2011-04

5-31

Installing and Connecting the HP Redundant / External Power Supplies

Recommended Connection Topologies

Limitations

EPS ports A1 and A2 share one common internal power supply; ports B1 and

B2 share a second common internal power supply. The maximum power that

can be supplied to each port pair is 408 W. In other words, if both ports in a

pair are connected to PoE switches, then the maximum power that each port

can provide is 204 W; but if only one port in a pair is connected to a PoE switch,

that port can provide up to 408 W.

In the illustration above, the four switches connected to the HP 610 EPS are

limited to 204 W of power on each EPS port. If a switch tries to draw more

than 204 W of power from the HP 610 EPS, an over-current condition occurs

and the EPS port shuts down. To supply more than 204 W on one EPS port,

the other port in the pair must first be disconnected. The maximum power

that can be provided when only one EPS port in a pair is connected to a switch

is 408 W.

Status Indication

The EPS Port Power Status LEDs on the HP 610 EPS indicate if an EPS port

is providing power to the connected device. For example, if four switches are

connected to the HP 610 EPS and the power to the switch on port A1 fails, the

Power Status LED for port A1 turns off, but for ports A2, B1, and B2 it remains

on.

EPS Backup Power

The purpose of the backup power is to provide redundancy to the PoE power

provided by the HP 610 EPS. Redundancy in PoE power can prevent loss of

power to PoE devices in the event of AC power failure or a power supply

failure on a connected HP 610 EPS.

Each HP 610 EPS incorporates a PoE power supply that is connected so it can

provide power to itself or another HP 610 EPS connected by a cable. The back

of the HP 610 EPS has backup power input and output connectors for

connecting multiple units together in a group, to back up each other. There

are two supported configurations for these groups:

■ Daisy chain, sometimes referred to as a string. In this configuration, one

HP 610 EPS provides backup power to all the other connected units.

Therefore, this backup unit must be the first unit in the string.

■ Closed loop, sometimes referred to as a ring. This allows for distributing

loads across all units. See Limitations, see page 5-33. HP recommends the

closed-loop configuration.