Juniper T4000 Hardware Manual page 229

Copyright © 2018, Juniper Networks, Inc.
inputs on the DC power supply in slot PEM1 must be powered by dedicated
power feeds derived from feed B. This configuration provides the commonly
deployed A/B feed redundancy for the system.
CAUTION: You must use an appropriate torque-controlled tool to tighten
the nuts. Applying excessive torque damages the terminal studs and the
power supply. The absolute maximum torque that may be applied to this nut
is 45 lb-in. (5.0 Nm).
CAUTION: You must ensure that power connections maintain the proper
polarity. The power source cables might be labeled
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: We recommend that the positive (+) DC source power cables to be
connected to the RTN (return) terminals be 2.6 in. (6.6 cm) longer than the
negative (–) DC source power cables to be connected to the –48 V (input)
terminals.
To connect 80-A DC source power cables to six inputs using a terminal jumper, follow
this procedure for each DC power supply:
Check your planned hardware configuration, and verify that three 80-A DC source
1.
power cables will provide sufficient power. See the DC power requirements for your
router for more information.
Verify that a properly rated customer site circuit breaker for each DC power cable has
2.
been installed. See the DC power electrical safety guidelines for your router for more
information.
Switch off the customer site circuit breakers. Ensure that the voltage across the DC
3.
power source cable leads is 0 V and that there is no chance that the cable leads might
become active during installation.
Verify that a licensed electrician has attached appropriate cable lugs to the DC power
4.
cables. See the DC power cable and lug specifications for your router for more
information.
Switch the power switch on the power supply faceplate to the standby position.
5.
Chapter 22: Connecting the Router to Power
and to indicate
(+) (–)
199