Juniper-networks MX480 Manual de usuario descargar pdf (Pagina 257)

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: Ensurethat each powercablelug 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.

CAUTION: The maximum torque rating of the terminal studs on the DC

power supply is 36 lb-in. (4.0 Nm). The terminal studs may be damaged

if excessive torque is applied. Use only a torque-controlled driver or socket

wrench to tighten nuts on the DC power supply terminal studs.

CAUTION: You must ensure that power connections maintain the proper

polarity. The power source cables might be labeled (+) and (–) to indicate

their polarity. There is no standard color coding for DC power cables. The

color coding used by the external DC power source at your site determines

the color coding for the leads on the power cables that attach to the

terminal studs on each power supply.

NOTE: The DC power supplies in PEM0 and PEM1 must be powered by

dedicated power feeds derived from feed A, and the DC power supplies

in PEM2 and PEM3 must be powered by dedicated power feeds derived

from feedB. This configuration provides the commonly deployedA/B feed

redundancy for the system.

NOTE: For information about connecting to DC power sources, see “DC

Power Supply Electrical Specifications for theMX480 Router” on page301.

9. Replace the clear plastic cover over the terminal studs on the faceplate.

10. Route the power cables along the cable restraint toward the left or right corner of the

chassis. If needed to hold the power cables in place, thread plastic cable ties, which

you must provide, through the openings on the cable restraint.

Chapter 14: Replacing MX480 Hardware Components

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Juniper-networks MX480 Manual de usuario Pagina 257