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26 CHAPTER 2: INSTALLING THE SWITCH
1500W rectifiers can provide up to 4500W. Hot removal or insertion of a rectifier
does not affect the -48V DC output voltage.
Table 7 shows an example of the total power available from several 1500W
rectifiers.
A minimum of two rectifiers are required for each shelf to provide N+1 rectifier
redundancy.
Table 7 Power Availability
The unearthed -48V DC power distribution provides the mechanism to connect to
the Switch 4500G. The distribution consists of several circuit breakers and
connection terminals for the positive (common) and negative -48V outputs.
Individually connect each Switch 4500G to a circuit breaker terminal.
You can also connect a battery to battery terminals prior to the DC power
distribution to provide uninterrupted power and to be protected 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 that 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 cables need
to be matched to the switch’s power rating.
Table 8 shows the recommended
circuit breaker and cable rating for the Switch 4500G. The recommended cable
length should not exceed three metres (9.84 feet).
Table 8 Switch 4500G Circuit Breaker and Cable Ratings
WARNING: Make sure to follow the RPS Manufacturers recommendations when
connecting the cable to the RPS.
WARNING: Ensure that the circuit breaker in the RPS is in the open (off) position
when connecting the cable to the RPS and the cable and connector to the switch.
WARNING: Ensure that the positive terminal on the switch is connected to the
positive (common) terminal of the RPS and that the negative terminal on the
switch is connected to the negative (circuit breaker) terminal of 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
PoE 25A C type 12 AWG (solid or stranded cable)