Juniper MX480 Hardware Manual page 393

NOTE: The minimum number of power supplies must be present in the router at all times.
WARNING:
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,
and tape the switch handle of the circuit breaker in the off position.
CAUTION:
power supply unit, each power supply slot must contain either a power supply or a
blank panel. If you remove a power supply, you must install a replacement power
supply or a blank panel shortly after the removal.
NOTE: After powering off a power supply, wait at least 60 seconds before turning it back on.
To remove a DC power supply (see
1. Switch off the dedicated customer site circuit breaker for the power supply being removed. Follow
your site's procedures for ESD.
2. Make sure that the voltage across the DC power source cable leads is 0 V and that there is no chance
that the cables might become active during the removal process.
3. 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.
4. Move the DC circuit breaker on the DC power supply faceplate to the off (O) position.
5. Remove the clear plastic cover protecting the terminal studs on the faceplate.
6. Remove the nut and washer from each of the terminal studs. (Use a 7/16-in. [11 mm] nut driver or
socket wrench.)
7. Remove the cable lugs from the terminal studs.
Before performing DC power procedures, ensure that power is removed
To maintain proper cooling and prevent thermal shutdown of the operating
Figure 141 on page 398):
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