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

The T640 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 Three-Input 240-A DC Power Supply
2. Setting the Input Mode Switch on a Three-Input 240-A DC Power Supply for a T640 Router
3. Installing a T640 Three-Input 240-A DC Power Supply
4. Replacing the T640 Cable Restraint on a Three-Input 240-A DC Power Supply
5. Connecting DC Power to a Three-Input 240-A DC Power Supply in a T640 Router
6. Powering On a T640 Replacement Three-Input 240-A DC Power Supply

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

1. Switch off the external 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).

   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 or wrench, remove the nuts and washers from the terminal studs (see Figure 1).

   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 1: Disconnecting Power Cables from the 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 three-input 240-A DC power supply weighs approximately 25 lb (11.3 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.

    Warning: Do not touch the power connectors on the rear of the power supply (see Figure 2). They can contain dangerous voltages.

    Figure 2: Rear of the Power Supply Showing Midplane Connectors

    

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

Setting the Input Mode Switch on a Three-Input 240-A DC Power Supply for a T640 Router

Note: Do not set the input mode switch if the power supply is installed in the chassis. If the power supply is already installed, you must disconnect all cables and remove the power supply before setting the input mode switch.

1. Using a screwdriver, loosen the captive screw holding the metal cover over the input mode switch (see Figure 4).
2. Rotate the metal cover away from the input mode switch to expose the switch.
3. Check the setting of the input mode switch. Use a flashlight, if necessary. In 2-INPUT mode, the switch must be located all the way to the right.
4. If the input mode switch is not set correctly, use a sharp, nonconductive object to slide the switch all the way to the right to set the power supply to 2-INPUT.

   Caution: Do not use a pencil, because fragments can break off and cause damage to the power supply.

5. Rotate the metal cover over the input mode switch, and use a screwdriver to tighten the captive screw.

Figure 4: Three-Input 240-A DC Power Supply

Installing a T640 Three-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 5).
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.

Figure 5: Installing a Three-Input 240-A DC Power Supply

Replacing the T640 Cable Restraint on a Three-Input 240-A DC Power Supply

Each three-input 240-A DC power supply is shipped with the standard cable restraint, as shown in Figure 6. Two optional cable restraints are shipped in the accessory box.

If your DC power cables are too large or inflexible to fit into the standard cable restraint, we recommend that you remove the standard cable restraint and install the optional cable restraint (see Figure 7) on each three-input 240-A DC power supply.

Note: Before you remove a chassis from a rack or cabinet, you must remove the optional cable restraint from the three-input 240-A DC power supply.

To replace the cable restraint on a three-input 240-A DC power supply, perform the following tasks:

• Removing the T640 Standard Cable Restraint from a Three-Input 240-A DC Power Supply
• Installing the T640 Optional Cable Restraint on a Three-Input 240-A DC Power Supply

Removing the T640 Standard Cable Restraint from a Three-Input 240-A DC Power Supply

1. Loosen the captive screw on the standard cable restraint or captive screws on the optional cable restraint.
2. Remove the cable restraint from the power supply.

Figure 6: Standard Cable Restraint on a Three-Input 240-A DC Power Supply

Installing the T640 Optional Cable Restraint on a Three-Input 240-A DC Power Supply

1. Align the two captive screws on the optional cable restraint with the two threaded holes located at the right edge of the power supply faceplate.
2. Fasten the captive screws.

Figure 7: Optional Cable Restraint on a Three-Input 240-A DC Power Supply

Connecting DC Power to a Three-Input 240-A DC Power Supply in a T640 Router

1. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist, and connect the strap to one of the ESD points on the chassis.
2. Verify that a licensed electrician has attached cable lugs to the power cables that you supply.
3. Verify that the voltage across the DC power source cables leads is 0 V and that there is no chance that the cables might become active during installation. If needed, switch off the customer site circuit breakers.
4. Verify that the circuit breakers on the power supply faceplate are in the OFF position (O).
5. Remove the clear plastic cover protecting the terminal studs on the faceplate.
6. 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.

7. Secure the cable lugs to the terminal studs, first with a washer, then with a nut (see Figure 8).
   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.

   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.

   Note: For power supplies set to 2-INPUT mode (required for the T640 router and TX Matrix router), connect two DC power cables, one for RETURN and one for –48 V to INPUT 0 and two DC power cables, one for RETURN and one for –48 V to INPUT 1.

   Note: INPUT 0 and INPUT 1 on the three-input 240-A DC power supply in slot PEM0 must be powered by dedicated power feeds derived from feed A, and INPUT 0 and INPUT 1 on the three-input 240-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.

8. Loosen the captive screw or screws on the cable restraint on the right edge of the power supply faceplate.
9. Route the DC power cables through the cable restraint.
10. Tighten the cable restraint captive screw or screws to hold the power cables in place.
11. Verify that the power cabling is correct, that the power cables are not touching or blocking access to other hardware components, and that they do not drape where people could trip on them.
12. Replace the clear plastic cover over the terminal studs on the faceplate.

Figure 8: Connecting Power Cables to the Power Supply

Powering On a T640 Replacement Three-Input 240-A DC Power Supply

1. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist, and connect the strap to one of the ESD points on the chassis.
2. Switch on the customer site circuit breakers to provide voltage to the DC power source cables.
3. Verify that the INPUT PRESENT LEDs on the power supply faceplate are lit steadily, indicating that the inputs are receiving power.
4. 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.

5. Verify that the CB ON LEDs on the power supply faceplate are lit steadily. The CB ON LEDs blink momentarily, then light steadily to indicate that the circuit breakers are on.
6. 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.

Note: After powering on a power supply, wait at least 60 seconds before turning it off. If the system is completely powered off when you power on the power supply, the Routing Engine boots as the power supply completes its startup sequence. If the Routing Engine finishes booting and you need to power off the system again, first issue the CLI request system halt command. After powering off a power supply, wait at least 60 seconds before turning it back on.