Figure 39: Connecting A Dc Power Supply Grounding Cable - Juniper MX104 Hardware Manual

MX104 3D Universal Edge Router Hardware Guide
102

Figure 39: Connecting a DC Power Supply Grounding Cable

Remove the screws and washers from the DC terminals.
6.
Verify that the DC power cables are correctly labeled before making connections to
7.
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 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 (
+
Secure each power cable lug to the terminal with the flat washers and screw (see
8.
Figure 41 on page 104). Apply up to 27.4 lb-in. (3.1 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 (
b. Secure the negative DC source power cable lug to the input (
CAUTION: Ensure that each power cable lug seats flush against the surface
of the terminal block as you are tightening the screws. Ensure that each
screw is properly threaded into the terminal. Applying installation torque
to the screw when improperly threaded may result in damage to the
terminal.
).
–
).
– ).
).
) terminal.
+
– ) terminal.
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