Juniper M7i User manual

Connecting Power to a DC-Powered M7i Router
Connect DC power to the router by inserting power cables into the field-wiring
terminals on the faceplate of each power supply. Power and grounding cables are
not supplied with the router. For information about the required cable type, see M7i
Chassis Grounding, Connection, and Cable Specifications.
NOTE: The router must be connected to at least two separate external DC power
sources.
CAUTION: 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.
You must ensure that power connections maintain the proper polarity. The power
source cables might be labeled (+) and (–)to indicate their polarity.
To connect DC power to the router (see Figure 1):
1. Verify that there is no power flowing from either external power source, so that
the 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.
2. For each power supply, verify that the power switch on the power supply faceplate
is in the OFF (O) position.
3. Connect the grounding cable to a proper earth ground for each external DC
power sources, if it is not already.
4. Verify that a licensed electrician has attached the cable lug provided with the
router to the grounding cable.
5. Using a number 2 Phillips screwdriver, remove the screws next to the grounding
symbol above the power supplies on the chassis rear. Secure the grounding cable
lug to the chosen grounding point by reinstalling and tightening the screws.
6. Verify that a licensed electrician has attached a listed power cable lug to each
power source cable.
7. Loop the power cables through the hook located on the faceplate to the right of
the field-wiring terminals.
8. Depending on the type of power cable lugs used, loosen or remove the screws
on the field-wiring terminals.
9. Insert the power cable lugs into the appropriate field-wiring terminals. Using a
number 1 Phillips screwdriver, turn the screw on each field-wiring terminal
clockwise to secure the power cable lug. Apply between 8 lb-in. (.9 Nm) and 9
lb-in. (1.02 Nm) of torque to each screw.
a. Insert the positive (+) source cable into the return terminal, which is labeled
RTN.
Connecting Power to a DC-Powered M7i Router ■1

b. Insert the negative (–) source cable into the input terminal, which is labeled
–48V.
10. Verify that the DC source power cabling and the grounding cabling are correct,
that they are not touching or blocking access to router components, and that
they do not drape where people could trip on them.
Figure 1: Connecting DC Power and Grounding Cables
Related Topics M7i Router DC Power Supply Specifications■
■M7i DC Power Electrical Safety Guidelines
■DC Power Wiring Sequence Warning for M Series, MX Series, and T Series Routers
Published: 2009-08-03
2■Connecting Power to a DC-Powered M7i Router