Juniper SRX550, Hardware Manual

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Connecting the SRX550 Services Gateway to a DC Power Source
CAUTION: Do not mix AC and DC power supplies within the same services gateway.
Damage to the device might occur.
A 645 W DC power supply with PoE support is available for the SRX550 Services Gateway.
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
(O), and tape the switch handle of the circuit breaker in the off position.
You connect DC power to the device by attaching power cables from the external DC power sources to
the terminals on the power supply faceplate. You must provide the power cables.
The power supply has two sets of terminals, to accommodate a redundant DC power feed. If one feed
fails, the services gateway draws its power from the other feed. The terminals for Feed A are labeled A+
and A-. The terminals for Feed B are labeled B+ and B-. You do not need to use both feeds; if you only
have one DC power source, or if you do not want to use feed redundancy, you can connect just one feed.
To connect the DC source power cables to the services gateway power supply:
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. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist, and connect the strap to
the ESD point on the back panel of the chassis.
3. Remove the clear plastic cover protecting the terminals on the power supply faceplate.
4. 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 large resistance (indicating an open circuit) to chassis ground will be –48V.
•
The cable with very low resistance (indicating a closed circuit) to chassis ground will be RTN.
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