Installing An Acx4000 Dc Power Supply - Juniper ACX4000 Hardware Manual

Installing an ACX4000 DC Power Supply

WARNING: Before performing DC power procedures, 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,
and tape the switch handle of the circuit breaker in the off position.
To install a DC power supply (see
1. 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 ESD grounding strap to your bare wrist, and connect the other end of the strap to an ESD
grounding point.
3. Using both hands, slide the power supply straight into the chassis until the power supply is fully
seated in the chassis slot. The power supply faceplate should be flush with any adjacent power
supply faceplate or blank installed in the power supply slot.
4. Remove the clear plastic cover protecting the terminal on the faceplate.
5. Remove the screws from the terminals.
6. 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 DC cables to chassis
ground:
For –48V and –60V:
a. The cable with very large resistance (indicating an open circuit) to chassis ground is the DC input
cable (–).
b. The cable with very low resistance (indicating a closed circuit) to chassis ground is the return
cable (+).
For +24V:
a. The cable with very low resistance (indicating a closed circuit) to chassis ground is the DC input
cable (–).
b. The cable with very large resistance (indicating an open circuit) to chassis ground is the return
cable (+).
7. Remove the screws and flat washers from the terminals.
8. Secure each power cable lug to the terminal with the flat washers and screw (see
between 8 lb-in. (0.9 Nm) and 9 lb-in. (1.02 Nm) of torque to each screw. Do not overtighten the
screw. (Use a number 2 Phillips screwdriver.)
a. Secure the positive DC source power cable lug to the return (+) terminal.
Figure 16):
Figure 17). Apply
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