Juniper Networks MX960 User Manual 2

MX960 Ethernet Services Router
DC Power Supply
Installation Instructions

19 October 2007
Part Number: 530-017577-01
Revision 2

This document describes how to remove and replace a DC power supply on a Juniper
Networks MX960 Ethernet Services Router.

Contents

DC Power Supply ............................................................................................2

DC Power Supply Electrical Specifications ................................................2

DC Power Supply LEDs .............................................................................3

Replacing a DC Power Supply .........................................................................4

Removing a DC Power Supply ..................................................................4

Installing a DC Power Supply ....................................................................7

List of Technical Publications ........................................................................10

Requesting Support .......................................................................................16

Revision History ............................................................................................16

■ 1

MX960 Ethernet Services Router DC Power Supply Installation Instructions

DC Power Supply

In the DC power configuration, the router contains either two or four DC power
supplies (see Figure 1 on page 2), located at the lower rear of the chassis in
slots PEM0 through PEM3 (left to right). You can upgrade your DC power system from
two to four power supplies. The DC power supplies in slots PEM0 and PEM2 provide
power to the lower fan tray, DPC slots 6 through 11, and SCB slots 1 and 2. The DC
power supplies in slots PEM1 and PEM3 provide power to the upper fan tray, DPC
slots 0 through 5, and SCB slot 0.

Four power supplies provide full redundancy. If a DC power supply fails, its redundant
power supply takes over without interruption.

Each DC power supply has a single DC input (–48 VDC and return) that requires a
dedicated 80 A (–48 VDC) circuit breaker for the maximum router hardware
configuration. For information about site power preparations and connecting the
router to power and ground, see the MX960 Ethernet Services Router Hardware Guide.

For DC power supply and power system electrical specifications, see Table 1 on page
3 and the MX960 Ethernet Services Router Hardware Guide.

Figure 1: DC Power Supply

DC Power Supply Electrical Specifications

2 ■ DC Power Supply

Table 1 on page 3 lists the DC power supply electrical specifications. For DC power
system electrical specifications, see the MX960 Ethernet Services Router Hardware
Guide.

Table 1: DC Power Supply Electrical Specifications

SpecificationItem

2800 WMaximum output power

DC Power Supply

DC Power Supply LEDs

Each DC power supply faceplate contains three LEDs that indicate the status of the
power supply (see Table 2 on page 3). The power supply status is also reflected in
two LEDs on the craft interface (see the MX960 Ethernet Services Router Hardware
Guide). In addition, a power supply failure triggers the red alarm LED on the craft
interface.

DC input voltage

Protector

Minimum: –40 VDC

Nominal: –48 VDC

Operating range: –40 to –72 VDC

NOTE: If the input voltage from the DC power source drops below

-37.5 to -39.5 VDC, the routing platform automatically shuts down.
During automatic shutdown, the circuit remains active. When the
input voltage returns to –43.0 to –44.00 VDC, the router
automatically starts up again and the system returns to normal
operation within 30 minutes. No operator intervention is required.

70 A maximum @ –48 VDC (nominal operating voltage)DC input current rating

80 AInternal Supplementary

Table 2: DC Power Supply LEDs

PWR OK

BREAKER
ON

INPUT OK

OffGreen

DescriptionStateColorLabel

Power supply is not functioning normally. Check the INPUT OK LED for more
information.

Power supply is functioning normally.On

DC power supply circuit breaker is turned off.OffGreen

DC power supply circuit breaker is turned on.On

DC input to the PEM is not present.OffGreen

DC input is present, and is connected in correct polarity.On

DC input is present, but connected in reverse polarity.OnAmber

DC Power Supply ■ 3

MX960 Ethernet Services Router DC Power Supply Installation Instructions

Replacing a DC Power Supply

To replace a DC power supply, use the following procedures:

■ Removing a DC Power Supply on page 4

■ Installing a DC Power Supply on page 7

Removing a DC Power Supply

The power supplies are located at the rear of the chassis. Each DC power supply
weighs approximately 3.8 lb (1.7 kg).

CAUTION: Do not leave a power supply slot empty for more than 30 minutes while
the router is operational. For proper airflow, the power supply must remain in the
chassis or a blank panel must be used in an empty slot.

NOTE: After powering off a power supply, wait at least 60 seconds before turning it
back on.

To remove a DC power supply, follow this procedure:

1. Make sure that the voltage across the DC power source cable leads is 0 V and

that there is no chance that the cables might become active during the removal
process.

2. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist and

connect the strap to one of the ESD points on the chassis. For more information
about ESD, see the MX960 Ethernet Services Router Hardware Guide.

3.

Switch the circuit breaker on the power supply faceplate to the OFF position.

4. Remove the clear plastic cover protecting the terminal studs on the faceplate.

5. Remove the nuts and washers from the terminal studs (see Figure 2 on page 5).

(Use a 3/8–in. nut driver or pliers.)

4 ■ Replacing a DC Power Supply

Replacing a DC Power Supply

Figure 2: Disconnecting Power Cables From the DC Power Supply

6. Remove the cable lugs from the terminal studs.

7. Loosen the captive screw on the cable restraint on the lower edge of the power

supply faceplate.

8. Carefully move the power cables out of the way.

9. While grasping the handle on the power supply faceplate with one hand, use

your other hand to pull the spring-loaded locking pin in the release lever away
from the chassis and turn the release lever counterclockwise until it stops (see
Figure 3 on page 6).

10. Let go of the locking pin in the release lever. Ensure that the pin is seated inside

the corresponding hole in the chassis.

11. Pull the power supply straight out of the chassis.

WARNING: Do not touch the power connector on the top of the power supply (see
Figure 4 on page 6). It can contain dangerous voltages.

Replacing a DC Power Supply ■ 5