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• Mulmeter (not provided)

Connecng DC Power to a QFX5200-32C-DC

To connect DC power to a QFX5200-32C:

1. Aach the grounding strap to your bare wrist and to a site ESD point.

2. Verify that the DC power cables are correctly labeled before making connecons to the power

supply. In a typical power distribuon scheme where the return is connected to chassis ground at

the baery plant, you can use a mulmeter to verify the resistance of the –48V and RTN DC cables

to chassis ground:

• The cable with very low resistance (indicang a closed circuit) to chassis ground is posive (+)

and will be installed on the V+ (return) DC power input terminal.

• The cable with very high resistance (indicang an open circuit) to chassis ground is negave (–)

and will be installed on the V– (input) DC power input terminal.

CAUTION: You must ensure that power connecons maintain the proper polarity.

The power source cables might be labeled (+) and (–) to indicate their polarity.

There is no standard color coding for DC power cables. The color coding used by

the external DC power source at your site determines the color coding for the leads

on the power cables that aach to the DC power input terminals on each power

supply.

3. Ensure that the input circuit breaker is open so that the voltage across the DC power source cable

leads is 0 V and that the cable leads do not become acve while you are connecng DC power.

NOTE: The V+ terminals are referred to as +RTN, and V– terminals are referred to as –48 V

in "DC Power Wiring Sequence Warning" on page 201 and "DC Power Electrical Safety

Guidelines" on page 197.

4. Ensure that the power supplies are fully inserted in the chassis.

5. Remove the terminal block cover. The terminal block cover is a piece of clear plasc that snaps into

place over the terminal block (see Figure 52 on page 119).

6. Remove the screws on the terminals using the screwdriver. Save the screws.

WARNING: Ensure that the power cables do not block access to device

components or drape where people can trip on them.

117

Juniper QFX5200 User Manual

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