Replacing a T640 Four-Input 240-A DC Power Supply

The router has either one nonredundant power supply or two redundant, load-sharing power supplies. Each redundant power supply is hot-insertable and hot-removable. When a redundant power supply is powered down or removed, the other power supply automatically assumes the entire electrical load for the router. If you have only one power supply, you must power off the system before removing the power supply.

1. Removing a T640 Four-Input 240-A DC Power Supply
2. Installing a T640 Four-Input 240-A DC Power Supply

Removing a T640 Four-Input 240-A DC Power Supply

1. Switch off the customer site circuit breakers to the power supply being removed. Make sure that the voltage across the DC power source cable leads is 0 V and that there is no chance that the cables might become active during the removal process.
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).

   Figure 1: Four-Input 240-A DC Power Supply

   

   Note: After powering off a power supply, wait at least 60 seconds before turning it back on.

4. Remove the clear plastic cover protecting the terminal studs on the faceplate.
5. Using a 7/16-in. (11 mm) nut driver, remove the nuts and washers from the terminal studs (see Figure 2).

   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.

   Figure 2: Disconnecting Power Cables from the Four-Input 240-A DC Power Supply

   
6. Remove the cable lugs from the terminal studs.
7. Loosen the captive screw or screws on the cable restraint on the right edge of the power supply faceplate.
8. Carefully move the power cables out of the way.
9. Loosen the captive screws on the lower corners of the power supply faceplate completely.
10. Twist the ejector handles on the upper corners of the faceplate counterclockwise to unseat the power supply.
11. Grasp the handle on the power supply faceplate and pull firmly. Slide it halfway out of the chassis (see Figure 3).

    Caution: Each four-input 240-A DC power supply weighs approximately 26.6 lb (12.0 kg). Be prepared to support the full weight of the power supply as you remove it from the router.

12. Place one hand underneath the power supply to support it and slide it completely out of the chassis.

    Figure 3: Removing a Four-Input 240-A DC Power Supply

    

    Warning: Do not touch the power connectors on the rear of the power supply (see Figure 4). They can contain dangerous voltages.

    Figure 4: Rear of the Power Supply Showing Midplane Connectors

    

Installing a T640 Four-Input 240-A DC Power Supply

1. Make sure that the voltage across the DC power source cable leads is 0 V and that there is no chance that the cables might become active during installation.
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. Using both hands, slide the power supply into the chassis until you feel resistance (see Figure 6).
5. Twist the ejector handles at the upper corners of the power supply faceplate clockwise until they stop.
6. Tighten the captive screws at the lower corners of the power supply faceplate to secure the power supply in the chassis.
7. Verify that a licensed electrician has attached cable lugs to the power cables that you supply.
8. Remove the clear plastic cover protecting the terminal studs on the faceplate.
9. Remove the nut and washer from each power terminal stud.

   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.

10. Attach the lugs on the DC source power cables to the terminal studs.
    1. Attach the positive (+) DC source power cable lugs to the RETURN (return) terminals.
    2. Attach the negative (–) DC source power cable lugs to the –48V (input) terminals.

    Secure the cable lugs to the terminal studs, first with a washer, then with a nut (see Figure 5). Use a 7/16-in. (11 mm) nut driver to tighten the nut. 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).

    Figure 5: Connecting a Power Cable to a Four-Input 240-A DC Power Supply

    
11. Loosen the captive screws on the cable restraint on the right edge of the power supply faceplate.
12. Route the DC power cables through the cable restraint.
13. Tighten the cable restraint captive screws to hold the power cables in place.
14. Verify that the power cabling is correct, that the power cables do not touch or block access to other hardware components, and that they do not drape where people could trip on them.
15. Replace the clear plastic cover over the terminal studs on the faceplate.
16. Switch on the customer site circuit breakers to provide voltage to the DC power source cables.
17. Verify that the INPUT PRESENT LEDs on the power supply faceplate are lit steadily, indicating that the inputs are receiving power.
18. Switch the circuit breakers on the power supply to the ON position (|).

    Note: After a power supply is powered on, it can take up to 60 seconds for status indicators—such as the LEDs on the power supply, the command output displays, and messages on the LED display on the craft interface—to indicate that the power supply is functioning normally. Ignore error indicators that appear during the first 60 seconds.

19. Verify that the CB ON LEDs on the power supply faceplate are lit steadily, indicating that the circuit breakers are on.
20. Verify that the DC OK LED on the power supply faceplate is lit steadily, indicating that the power supply is correctly installed and is functioning properly. The DC OK LED blinks momentarily, then lights steadily.

Figure 6: Installing a Four-Input 240-A DC Power Supply