Connecting DC Power to a T640 Router with Four-Input 240-A DC Power Supplies

You connect DC power to the router by attaching power cables from the DC power sources to the terminal studs on the power supply faceplates. You must provide power cables (the cable lugs are supplied with the router).

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.

   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.

2. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist, and connect the strap to one of the ESD points on the chassis.
3. Switch the circuit breakers on the power supply faceplate to the OFF position (O).
4. Remove the clear plastic cover protecting the terminal studs on the faceplate.
5. 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.
6. Attach the lugs on the DC source power cables to the terminal studs. Secure the cable lugs to the terminal studs, first with the washers, then with the nuts.
   1. Attach the positive (+) DC source power cable lugs to the RTN (return) terminals.
   2. Attach the negative (–) DC source power cable lugs to the –48V (input) terminals.

   Using a 7/16-in. (11 mm) nut driver, tighten the nuts (see Figure 1). Apply between 23 lb-in. (2.6 Nm) and 25 lb-in. (2.8 Nm) of torque to each nut.

   Caution: You must use an appropriate torque-controlled tool to tighten the nuts. Applying excessive torque damages the terminal studs and the power supply. The absolute maximum torque that may be applied to this nut is 45 in-lb (5.0 Nm).

   Caution: All inputs on the DC power supply in slot PEM0 must be powered by dedicated power feeds derived from feed A, and all inputs on the 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.

7. Loosen the captive screws on the cable restraint on the right edge of the power supply faceplate (using a Phillips (+) screwdriver, number 2).
8. Route the positive and negative DC power cables through the cable restraint.
9. Tighten the cable restraint captive screws to hold the power cables in place.
10. 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.
11. Replace the clear plastic cover over the terminal studs on the faceplate.

Figure 1: Connecting Power to the Four-Input 240-A DC Power Supply