EPS 2011-04

5-34

Installing and Connecting the HP Redundant / External Power Supplies

Recommended Connection Topologies

There is a need for some way to ensure this requirement is met. There are two

ways to do this:

■ Sum up all the loads and divide by 850 W (round up to next whole number),

this gives you the required number of HP 610 EPS units. Now for backup

redundancy add one more HP 610 EPS unit.

■ Do not put any load on ONE of the HP610 EPS units, (in a string this must

be the “First” unit). See the illustration and note on page 5-32.

For example, you have 150 phones at 8 W each and 10 wireless access points

at 12 W each, this totals 1320 W. Now you must divide 1320 W by 850 W (the

power of one HP 610 EPS) to get the number of units you will need to support

the 1320 W. 1320 W divided by 850 W equals 1.55. Therefore, you need two

HP 610 EPS units to support these devices. You must round up to the next

whole number. For full backup redundancy, you will need to add one more

HP 610 EPS for a total of three units.

The loads do not have to be distributed equally, for example:

■ With four HP 610 EPS units in a ring, redundancy is achieved if unit A has

a full single load, and B, C, and D each have 2/3 of a maximum single load.

■ With four HP 610 EPS units in a ring, redundancy is achieved if A, B, C,

and D each have 3/4 of a maximum single load.

■ With five HP 610 EPS units, redundancy is achieved if four units have the

maximum single load, and one unit has zero load.

■ With five HP 610 EPS units, redundancy is achieved if all five units have

4/5 of a maximum single load.

All the preceding examples require a closed-loop configuration. If any unit in

the chain fails, all units then share their power to support the failed unit.

Status Indication

The backup power connector status LEDs indicate if an HP 610 EPS is

connected to another HP 610 EPS unit, and the other unit is powered on. On

the front of the HP 610 EPS there are two LEDs indicating the status of the

backup power. One LED is labeled “IN,” and when it is ON it indicates the

backup power input is connected to another live HP 610 EPS backup power

output.

The other LED is labeled “Out,” and when it is on, it indicates the backup

power output is connected to another HP 610 EPS backup power input.