Connecting The Srx345 Firewall To A Dc Power Supply - Juniper SRX345 Hardware Manual

Connecting the SRX345 Firewall to a DC Power Supply

You connect DC power to the services gateway by attaching power cables from the external DC power
sources to the terminal studs on the rear panel of the services gateway.
WARNING: To meet safety and electromagnetic interference (EMI) requirements and to
ensure proper operation, you must properly ground the services gateway chassis before
connecting power. See
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WARNING: Before performing the following procedure, ensure that power is removed
from the DC circuit. To ensure that all power is off, locate the circuit breaker on the
panel board that services the DC circuit, switch the circuit breaker to the off position
(0), and tape the switch handle of the circuit breaker in the off position.
CAUTION: Before you connect power to the services gateway, a licensed electrician
must attach appropriate cable lugs to the grounding and power cables that you use. A
cable with an incorrectly attached lug can damage the device (for example, by causing a
short circuit).
To connect the DC source power cables to the services gateway:
1. Switch off the dedicated facility circuit breakers. Ensure that the voltage across the DC power source
cable leads is 0 V and that there is no chance that the cable leads might become active during
installation.
2. Remove the clear plastic cover that protects the terminal studs.
3. 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 ohm output of the -48V and RTN DC cables to chassis
ground. The cable with very large resistance (indicating an open circuit) to chassis ground is -48V, and
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 (+) and (–) to indicate their polarity. There is no
standard color coding for DC power cables. The color coding used by the external DC
"Connecting the SRX345 Services Gateway Grounding Cable"
for instructions.
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