Juniper QFX3500, Hardware Documentation

Page: 315 / 669

The terminal block of the 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.
CAUTION: The connection between each power source and power supply must
include a circuit breaker.
Do not connect two sources to a single power supply because doing so can
potentially cause circulating current in feed wires whenever there is any difference
in the voltage of the two sources.
NOTE: For QFX5100-96S installations using battery backup, a single 15 A circuit breaker is
recommended.
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.
291