Juniper MX204 Hardware Manual page 65

MX204 3D Universal Edge Router Hardware Guide
78
You connect DC power to the router by attaching power cables from the external DC
power sources to the terminal on the power supply faceplate. You must provide the
power cables (the cable lugs are supplied with the router). For power cable specifications,
see "DC Power Cable Specifications for MX204 Router" on page
To connect the DC source power cables to the router for each power supply:
Switch off the dedicated customer-site circuit breakers. Ensure that the voltage across
1.
the DC power source cable leads is 0 V and that there is no chance that the cable
leads might become active during installation.
Attach an ESD grounding strap to your bare wrist and connect the strap to one of the
2.
ESD points on the chassis.
Verify that the DC power cables are correctly labeled before making connections to
3.
the power supply. In a typical power distribution scheme where the return is connected
to chassis ground at the battery plant, you can use a multimeter to verify the resistance
of the and DC cables to chassis ground:
–48V RTN
The cable with very large resistance (indicating an open circuit) to chassis ground
is .
–48V
The cable with very low resistance (indicating a closed circuit) to chassis ground is
.
RTN
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.
Remove the screws from the terminals.
4.
Secure each power cable lug to the terminal with the screws (see
5.
Figure 38 on page 79). Apply between 5 lb-in. (0.6 Nm) and 6 lb-in. (0.7 Nm) of torque
to the screws. Do not overtighten the screws. (Use a socket nut driver.)
a. Secure the positive (+) DC source power cable lug to the
b. Secure the negative (–) DC source power cable lug to the
CAUTION: Ensure that each power cable lug seats flush against the surface
of the terminal block as you are tightening the screws. Ensure that each
nut is properly threaded into the terminal. Applying installation torque to
the screws when improperly threaded can result in damage to the terminal.
53.
and to indicate
(+) (–)
(return) terminal.
RTN
(input) terminal.
–48V
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