Power Supplies - Juniper M40 Hardware Manual

Power Supplies

Power Supplies
20 M40 Internet Router Hardware Guide
The interface ports with the indicated label function as follows:
MANAGEMENT ETHERNET
to a management LAN (or any other device that plugs into an Ethernet connection) for
out-of-band management. The port uses an autosensing RJ-45 connector to support both
10- and 100-Mbps connections.
—Connects the Routing Engine to a system console through an RS-232
CONSOLE
(EIA-232) serial cable.
AUXILIARY — Connects the Routing Engine to a laptop, modem, or other auxiliary device
through an RS-232 (EIA-232) serial cable.
For information about the pinouts for the connectors, see "Cable Connectors and Pinouts" on
page 207.
The router can use either AC or DC power. In either case, there are two load-sharing power
supplies that install into the bays located at the bottom rear of the chassis, as shown in
Figure 2. As viewed from the rear of the chassis, the supply on the left is referred to as supply
A and the supply on the right as supply B. The power supplies connect to the backplane,
which distributes power to router components according to their individual voltage
requirements. Each power supply has a system ground connector and an integrated fan to
cool the power assembly.
The power supplies are fully redundant. When both power supplies are operational, they
automatically share the electrical load. If one power supply stops functioning for any reason,
the remaining power supply instantly begins providing all the power the router needs for
normal functioning, and can provide full power indefinitely.
Power supplies are hot-removable and hot-insertable, as described in "Field-Replaceable
Units (FRUs)" on page 4. Each power supply has a safety interlock lever that prevents
removal of the supply while it is on, but to avoid electrical injury, carefully follow the
instructions in "Replace an AC Power Supply" on page 136 and "Replace a DC Power Supply"
on page 141.
.
After powering off a power supply, wait at least 60 seconds
before turning it back on. After powering on a power
supply, wait at least 60 seconds before turning it off.
If the router is completely powered down when you power
on a power supply, the Routing Engine boots as the power
supply completes its startup sequence. If the Routing
Engine finishes booting and you need to power down the
router again, first issue the CLI
command.
After a power supply is powered on, it can take up to 60
seconds for status indicators—such as LEDs on the power
supply, show chassis commands, and messages on the
craft interface LCD—to indicate that the power supply is
functioning normally. Ignore error indicators that appear
during the first 60 seconds.
—Connects the Routing Engine through an Ethernet connection
request system halt