3Com Switch 4500 Family, Getting Started Manual, Page: 31 / 134

Connecting a Redundant Power Supply to your Switch 4500 PWR 31
Table 9 Power Availability
The -48V DC power distribution provides the mechanism to connect to
the Switch 4500 PWR. The distribution consists of a number of circuit
breakers and connection terminals for the positive (common) and
negative -48V outputs. Each Switch 4500 PWR 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.
3Com’s RPS solution uses -48V DC power distribution. The RPS system
provides bulk -48V DC power that is separately distributed to a number
of network switches.
Each RPS consists of a shelf which can house from one to six rectifiers, a
Distribution Module and a Management Module.
Connecting the
Switch to the
Redundant Power
System
When connecting the RPS to the Switch, the circuit breaker and 2-core
cable need to be matched to the power rating of the Switch. Table 10
shows the recommended circuit breaker and cable rating for the Switch
4500. The recommended cable length should not exceed 3 meters (9.84
feet).
Table 10 Switch 4500 Circuit Breaker and Cable Ratings
WARNING: RPS Manufacturers recommendations must be followed
when connecting the cable to the RPS.
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
Circuit Breaker Minimum 2-Core Cable Diameter
Non PoE 6A C type 18 AWG (solid or stranded cable)
PoE 25A C type 12 AWG (solid or stranded cable
)