CHAPTER 11
DC Power Requirements and
Specifications
•
M120 DC Power, Connection, and Cable Specifications on page 97
•
Electrical Specifications for the M120 DC Power Supply on page 100
M120 DC Power, Connection, and Cable Specifications
In the DC power configuration, the router contains two DC power supplies (see Figure 20
on page 72), located in the right rear of the chassis in slots PEM0 and PEM1 (left to right).
A single DC power supply provides sufficient power for a fully configured router.
Two DC power supplies share power almost equally within a fully populated system. If
either power supply fails, the remaining power supply takes over without interruption.
Each DC power supply has a single DC input (–48 VDC and return) that requires a
dedicated 60 A (–48 VDC) circuit breaker for the maximum router hardware configuration.
Most sites distribute DC power through a main conduit that leads to frame-mounted DC
power distribution panels, one of which might be located at the top of the rack that
houses the router. A pair of cables (one input and one return) connects each set of
terminal studs to the power distribution panel.
NOTE: If you plan to operate a maximally configured DC-powered router, we
recommend that you provision at least 60 A @ –48 VDC for the system. Use
a facility circuit breaker rated for 60 A (–48 VDC) minimum for each DC
power supply. Doing so enables you to operate the router in any configuration
without upgrading the power infrastructure.
If you plan to operate a DC-powered router at less than the maximum
configuration and do not provision a 60 A (–48 VDC) circuit breaker, we
recommend that you provision a circuit breaker for each DC power supply
rated for at least 125% of the continuous current that the system draws at
–48 VDC.
97Copyright © 2018, Juniper Networks, Inc.
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