Installing the MX240 and MX480 DC High-Capacity Power Supplies
NOTE: During the upgrade process, you can simultaneously run existing and
high-capacity power supplies. However, it is recommended to upgrade all
power supplies to high-capacity power supplies.
WARNING: Before performing DC power procedures, ensure that power is
removed from the DC circuit. To ensure that all power is off, locate the circuit
breaker on the panel board that services the DC circuit, switch the circuit
breaker to the off position, and tape the switch handle of the circuit breaker
in the off position.
To install a DC power supply (see Figure 16 on page 21):
1. Ensure that the voltage across the DC power source cable leads is 0 V and that there
is no chance that the cable leads might become active during installation.
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.
3. Move the DC circuit breaker on the power supply faceplate to the off (O) position.
4. Using both hands, slide the power supply straight into the chassis until the power
supply is fully seated in the chassis slot. The power supply faceplate should be flush
with any adjacent power supply faceplate or blank installed in the power supply slot.
5. Tighten the captive screws on the lower edge of the power supply faceplate.
6. Remove the clear plastic cover protecting the terminal studs on the faceplate.
7. Remove the nut and washer from each of the terminal studs.
8. Secure each power cable lug to the terminal studs, first with the flat washer, then
with the split washer, and then with the nut (see Figure 17 on page 22). Apply between
23 lb-in. (2.6 Nm) and 25 lb-in. (2.8 Nm) of torque to each nut. Do not overtighten the
nut. (Use a 7/16-in. [11 mm] torque-controlled driver or socket wrench.)
a. Secure the positive (+) DC source power cable lug to the RTN (return) terminal.
b. Secure the negative (–) DC source power cable lug to the –48V (input) terminal.
CAUTION: Ensure that each power cable lug seats flush against the surface
of the terminal block as you are tightening the nuts. Ensure that each nut
is properly threaded onto the terminal stud. The nut should be able to spin
freely with your fingers when it is first placed onto the terminal stud.
Applying installation torque to the nut when improperly threaded may
result in damage to the terminal stud.
19Copyright © 2010, Juniper Networks, Inc.
Installing the MX240 and MX480 DC High-Capacity Power Supplies
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