Figure 17: Connecting The Ground Cable To The Mx104 Dc Power Supply - Juniper MX104 Hardware Manual

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To connect the power cables:
Switch off the dedicated customer site circuit breakers. Ensure that the voltage across
1.
the DC power source cable leads is 0 V and that there is no chance that the cable
leads might become active during installation.
Ground the DC power supply (see
2.
Remove the nut and washer from the grounding point on the power supply.
a.
Secure each grounding cable lug to the grounding point with the washer and nut.
b.

Figure 17: Connecting the Ground Cable to the MX104 DC Power Supply

Remove the plastic cover protecting the terminal on the faceplate.
3.
Verify that the DC power cables are correctly labeled before making connections to
4.
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 –48V and return DC cables to chassis ground:
For –48V and –60V:
a. The cable with very high 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 high resistance (indicating an open circuit) to chassis ground
is the return cable ( +
Remove the screws and washers from the terminals.
5.
Chapter 8: Grounding and Providing Power to the MX104 Router
Figure 17 on page
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