Juniper QFX3500, Hardware Documentation

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CAUTION: The DC power supply has four terminals labeled V+, V+, V–, and V–
for connecting DC power source cables labeled positive (+) and negative (–). The
V+ terminals are shunted internally together, as are the V- terminals. The same
polarity terminal can be wired together from the same source to provide an
additional current path in a higher power chassis. Do not connect the terminals to
different sources. For example, connect –48 V from DC source feed A to the input
terminals of one power supply and connect –48 V from feed B to the input terminals
of the second power supply on the other side of the chassis. This configuration
provides the commonly deployed A/B feed redundancy for the system.
a. Secure the ring lug of the positive (+) DC power source cable to the V+ terminal on the DC power
supply.
b. Secure the ring lug of the negative (–) DC power source cable to the V– terminal on the DC power
supply.
c. Tighten the screws on the power supply terminals until snug using the screwdriver. Do not
overtighten—apply between 5 in-lb (0.56 Nm) and 6 in-lb (0.68 Nm) of torque to the screws.
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