Juniper ACX7100-32C Hardware Manual page 80

• DC power source cables 10-12 AWG (not provided)
• Phillips (+) screwdriver, number 2 (not provided)
• Multimeter (not provided)
The power supply module (PSM) in an ACX7100-32C router is a hot-removable and hot-insertable field-
replaceable unit (FRU). You can remove and replace it without powering off the router or disrupting
routing functions.
WARNING: DC-powered ACX7100-32C routers are intended for installation only in a
restricted-access location.
NOTE: The battery returns of the DC power supply must be connected as an isolated DC return
(DC-I).
To connect DC power to an ACX7100-32C router:
1. Wrap and fasten one end of the ESD grounding strap around your bare wrist, and connect the
other end of the strap to the ESD point on the chassis.
2. Verify that the DC power cables are correctly labeled before making connections to 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 –48V and RTN DC cables
to chassis ground:
• The cable with very low resistance (indicating a closed circuit) to chassis ground is positive (+).
You install this cable on the V+ (return) DC power input terminal.
• The cable with very high resistance (indicating an open circuit) to chassis ground is negative (–).
You install this cable on the V– (input) DC power input terminal.
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 DC power input terminals on each PSM.
3. Ensure that the input 2-pole circuit breaker is open so that the voltage across the DC power source
cable leads is 0 V and that the cable leads do not become active while you are connecting DC
power.
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