3com Switch 4500G 24-Port Switch 4500G 48-Port Switch 4500G PWR 24-Port Switch 4500G PWR 48-Port Manual De Usuario

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C
HAPTER
 2: I
NSTALLING
 
THE
 S
WITCH
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
)