3Com 4500 Getting Started Manual page 24

24 C 2: I
HAPTER NSTALLING THE
Specifying the
Redundant Power
System
S
WITCH
Table 7 Switch Power Inputs
Table 8
Power Input before Power Input after
User Intervention User Intervention
AC mains and RPS RPS only
AC mains and RPS AC mains only
RPS only AC mains and RPS
AC mains AC mains and RPS
3Com's redundant power solution allows the use of any off-the-shelf -48V DC RPS
that meets the requirements defined in Appendix E "Technical Specifications"
on page 79.
For an approved vendor list, more details about purchasing the 3Com
recommended RPS and a full set of requirements go to:
http://www.3Com.com/RPS
The 3Com recommended RPS generates -48V DC power using power supply units
(or rectifiers). The outputs of the rectifier(s) are connected together so that the
total -48V power available can be increased by adding additional rectifiers. For
example, three 1500W rectifiers can provide up to 4500W. Hot removal or
insertion of a rectifier will not affect the -48V DC output voltage.
Table 9 shows an example of the total power available from a number of 1500W
rectifiers.
A minimum of two rectifiers are required for each shelf to provide N+1 rectifier
redundancy.
Table 9 Power Availability
Table 10
1
No Rectifier 1500W
Redundancy
N+1 Rectifier -
Redundancy
Correct Response
The unit remains powered by the RPS.
The unit is powered by the AC mains.
PoE dropped on all ports, however
the unit does not reset. PoE restarts
powered by the remaining power
from the AC mains. PoE ports will be
dropped depending on their preset
priority level.
The total power available to the
Switch may be less than when
powered from the RPS. Some PoE
ports may be dropped as they are
unable to obtain the power they
require.
The unit remains powered by the RPS.
The unit is powered by the RPS. PoE
ports can be added.
Rectifiers
2 3 4
3000W 4500W 6000W
1500W 3000W 4500W
5 6
7500W 9000W
6000W 7500W