3Com 3CR17251-91 - Switch 5500G-EI Stackable Gigabit Ethernet - Specifying the Redundant Power System

36 CHAPTER 2: INSTALLING THE SWITCH
Specifying the
Redundant Power
System
3Com’s redundant power solution allows the use of any off-the-shelf
-48V DC RPS that meets the requirements defined in Appendix C
on
page 127
.
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 10
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 10 Power Availability
The unearthed -48V DC power distribution provides the mechanism to
connect to the Switch 5500. The distribution consists of a number of
circuit breakers and connection terminals for the positive (common) and
negative -48V outputs. Each Switch 5500 must be individually connected
to a circuit breaker terminal.
A battery can also be connected to battery terminals prior to the DC
power distribution to provide uninterrupted power in order to protect
against the loss of AC mains power.
Rectifiers
1 2 3 4 5 6
No Rectifier
Redundancy
1500W 3000W 4500W 6000W 7500W 9000W
N+1 Rectifier
Redundancy
- 1500W 3000W 4500W 6000W 7500W