Connecting DC Power to a T640 Router with Two-Input 160-A DC Power Supplies

To connect the DC source power cables to each power supply in the T640 router:

1. Switch off the dedicated customer site circuit breakers. Follow the instructions for your site. 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. Switch the circuit breakers on the power supply faceplate to the off position (O).
3. Remove the clear plastic cover protecting the terminal studs on the faceplate.
4. Remove the nut and washer from each power terminal stud. If no washers and nuts are already installed, they should be in the accessory box.
5. Secure the cable lug on the DC power cable to the terminal stud, first with a washer, then with a nut (see Figure 1). Use a 7/16-in. (11 mm) nut driver or wrench to tighten the nut. Apply between 23 lb-in. (2.6 Nm) and 25 lb-in. (2.8 Nm) of torque to each nut:
   1. Secure each positive (+) DC source power cable lug to a RTN (return) terminal.
   2. Secure each negative (–) DC source power cable lug to a –48V (input) terminal.

   Note: All inputs on the two-input 160-A DC power supply in slot PEM0 must be powered by dedicated power feeds derived from feed A, and all inputs on the two-input 160-A DC power supply in slot PEM1 must be powered by dedicated power feeds derived from feed B. This configuration provides the commonly deployed A/B feed redundancy for the system.

   Caution: You must ensure that power connections 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 attach to the terminal studs on each power supply.

6. Loosen the captive screws on the cable restraints on the right edge of the power supply faceplate.
7. Route the positive and negative DC power cables through the top and bottom of each cable restraint.
8. Tighten the cable restraint captive screws to hold the power cables in place.
9. Verify that the power cabling is correct, that the power cables are not touching or blocking access to router components, and that they do not drape where people could trip on them.
10. Replace the clear plastic cover over the terminal studs on the faceplate.

Figure 1: Connecting DC Power to a Two-Input 160-A DC Power Supply