Juniper M40E Hardware Manual page 149

Copyright © 2010, Juniper Networks, Inc.
NOTE: The router must be connected to at least two separate external DC
power sources.
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 the circuit breaker box.
To connect DC power to the router (see Figure 70 on page 122):
Verify that there is no power flowing from either external power source, so that the
1.
voltage across the leads of the power cables is 0 V. Ensure that there is no chance
that the cable leads might become active during the procedure.
For each power supply, verify that the power switch on the circuit breaker box is in the
2.
( ) position.
OFF O
Using a Phillips screwdriver, loosen and remove the screws securing the protective
3.
shield over the terminal studs on the circuit breaker box. Remove the cover.
Install one flat washer and one nut (in that order) on each power terminal stud:
4.
If no washers and nuts are already installed, they should be in the accessory box.
If two pairs of nuts and washers are installed on the studs, use a 7/16-in. nut driver
or wrench to loosen the outer nut on each stud. Remove the outer nuts and washers,
leaving the inner nut and washer on each stud.
CAUTION: The inner washer and nut prevent direct contact between
the power cable lug and the circuit breaker box, which can cause a short
circuit.
Slide the power cable lugs onto the terminal studs. Install another washer and nut (in
5.
that order) on each terminal stud to secure each power cable lug.
a. Connect the positive (+) source cable lugs to the return terminals, which are labeled
RTN(+) .
b. Connect the negative (–) source cable lugs to the input terminals, which are labeled
.
–48V
Using a 7/16-in. nut driver or wrench, tighten the nuts. Apply between 23 lb-in. (2.6
Nm) and 25 lb-in. (2.8 Nm) of torque to each nut.
Bend the power cables at a radius appropriate for the AWG being used and tie them
6.
together to ensure that the power cables do not obstruct any other components. To
identify the minimum bend radius for each type of power cable types, see published
Chapter 12: Providing Power to the M40e Router
and
(+) (–)
to indicate
121