Installing An Mx2020 Dc Power Supply Module (-48 V) - Juniper MX2020 Hardware Manual

Installing an MX2020 DC Power Supply Module (-48 V)

Before you install a PSM, be aware of the following:
NOTE: The DC PSM is hot-swappable when a minimum number of PSMs installed and operational.
WARNING:
current from the router. After DC feeds have been connected to the PDM, the DC
voltage is always present on the power midplane and is distributed to the PSM
connectors on the power midplane.
CAUTION:
PSM, each PSM slot must contain either a PSM or a blank panel. If you remove a PSM,
you must install a replacement PSM or a blank panel shortly after the removal.
NOTE: After powering on a PSM, wait at least 60 seconds before turning it back off.
To install a DC PSM (see
1. With one PSM installed and operational, install an additional PSM with the power supply switch in the
off (O) or in the on (|) position.
CAUTION:
switch must be placed in the off (O) position.
2. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist, and connect the strap to
one of the ESD points on the chassis.
3. While grasping the handle on the PSM faceplate with one hand, use your other hand to guide the power
supply module into the chassis.
4. Tighten the captive screws on the PSM faceplate. Apply between 10 lb-in. (1.13 Nm) to 12 lb-in.
(1.35 Nm) of torque to each screw. Do not overtighten the screws.
The DC PSMs have no circuit breakers that can physically disconnect DC
To maintain proper cooling and prevent thermal shutdown of the operating
Figure 199 on page 407):
If there is only one PSM installed and operational, the power supply
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