M120 Power Supplies Description; M120 Ac Power Supply Description - Juniper M120 Hardware Manual

M120 Power Supplies Description

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M120 AC Power Supply Description

Copyright © 2010, Juniper Networks, Inc.
M120 AC Power Supply LEDs on page 30
M120 DC Power Supply Description on page 31
M120 DC Power Supply LEDs on page 32
The M120 router is configurable with either one or two AC or DC power supplies. The
power supplies connect to the midplane, which distributes the different output voltages
produced by the power supplies to the router components, depending on their voltage
requirements.
All power supplies are hot-removable and hot-insertable.
NOTE: To maintain proper cooling and prevent thermal shutdown of the
operating power supply unit, each power supply slot must contain either a
power supply or a blank panel. If you remove a power supply, you must install
a replacement power supply or a blank panel shortly after the removal.
CAUTION: Mixing AC and DC power supplies is not supported. The first power
supply powered on will electrically disable the second power supply without
damaging any components in the system.
Power Supply LEDs on the M120 Craft Interface on page 28
M120 AC Power Supply Description on page 29
M120 DC Power Supply Description on page 31
Connecting Power to an AC-Powered M120 Router on page 89
Connecting Power to a DC-Powered M120 Router on page 91
Maintaining the M120 Power Supplies on page 115
In the AC power configuration, the router contains two AC power supplies (see Figure 14
on page 30), located vertically at the rear of the chassis in slots
to right). Each AC power supply provides power to all components in the router. When
two power supplies are present, they share power almost equally within a fully populated
system.
Two AC power supplies provide full power redundancy. If one power supply fails or is
removed, the remaining power supply instantly assumes the entire electrical load without
interruption. One power supply provides the maximum configuration with full power for
as long as the router is operational.
Chapter 2: M120 Hardware Components
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PEM0 PEM1
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