Connecting DC Power to the Router

Connect DC power to the router by attaching a grounding cable to the chassis grounding points and attaching power cables from external power sources to the terminal studs on the power supply faceplate. Power and grounding cables are not supplied with the router. For cable specifications, see Chassis Grounding.

Note: The router must be connected to at least two separate external DC power sources.

Caution: 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 the power supply faceplate. You must ensure that power connections maintain the proper polarity. The power source cables might be labeled (+) and (–) to indicate their polarity.

To connect DC power to the router, follow this procedure (see Figure 75):

1. Verify that there is no power flowing from either external power source, so that the voltage across the leads of the power cables is 0 V. Ensure that there is no chance that the cable leads might become active during the procedure.
2. For each power supply, verify that the power switch on the power supply faceplate is in the OFF (O) position.
3. Connect the grounding cable to a proper earth ground.
4. Verify that a licensed electrician has attached the cable lug provided with the router to the grounding cable.
5. Make sure that grounding surfaces are clean and brought to a bright finish before grounding connections are made.
6. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist and connect the strap to one of the ESD points on the chassis. For more information about ESD, see Preventing Electrostatic Discharge Damage.
7. Place the grounding cable lug over the grounding points.The grounding points are sized for 1/4-20 UNC screws.
8. Secure the grounding cable lug to the grounding points, first with the washers, then with the screws.
9. Verify that the grounding cabling is correct, that the grounding cable does not touch or block access to router components, and that it does not drape where people could trip on it.
10. Using a Phillips screwdriver, loosen and remove the screws securing the protective shield over the terminal studs on the power supply faceplate. Remove the cover.
11. Install one flat washer and one nut (in that order) on each power terminal stud:
    • If no washers and nuts are already installed, they should be in the accessory box.
    • If two pairs of nuts and washers are installed on the studs, use a 7/16-in. nut driver or wrench to loosen the outer nut on each stud. Remove the outer nuts and washers, leaving the inner nut and washer on each stud.

      Caution: Do not substitute a metric nut driver or wrench. A tool that does not fit the nuts exactly can damage them.

      Caution: The inner washer and nut prevent direct contact between the power cable lug and the power supply faceplate, which can cause a short circuit.

12. Slide the power cable lugs onto the terminal studs. Install another washer and nut (in that order) on each terminal stud to secure each power cable lug.
    1. Connect the positive (+) source cable lugs to the return terminals, which are labeled RTN.
    2. Connect the negative (–) source cable lugs to the input terminals, which are labeled –48V.

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

13. Bend the power cables at a radius appropriate for the AWG being used and tie them together to ensure that the power cables do not obstruct any other components. To identify the minimum bend radius for each type of power cable types, see published industry standards, such as the National Electrical Code (NEC) and Insulated Cable Engineers Association (ICEA). Do not bend a power cable beyond the specified minimum bend radius.
14. Verify that the source power cabling and the grounding cabling are correct, that they are not touching or blocking access to router components, and that they do not drape where people could trip on them.
15. Replace the protective shield over the terminal studs and use a Phillips screwdriver to tighten the screws.
16. Turn on the DC power source so that voltage flows to the router.
17. Turn on the power to a management device that is connected to the master Routing Engine (through the craft interface port labeled AUX/MODEM, CONSOLE, or MGMT). For more information on connecting management devices, see Connecting the Router to Management and Alarm Devices.
18. Press the power switch on one power supply faceplate to the ON position. Verify that the green OK LED eventually lights steadily and the amber FAULT LED does not light.

    Note: After powering off a power supply, wait at least 60 seconds before turning it back on. After powering on a power supply, wait at least 60 seconds before turning it off. If the router 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 router again, first issue the CLI request system halt command. For more information, see Disconnecting AC Power from the Router or Disconnecting DC Power from the Router. After a power supply is powered on, it can take up to 60 seconds for status indicators—such as LEDs on the power supply and show chassis commands—to indicate that the power supply is functioning normally. Ignore error indicators that appear during the first 60 seconds.

19. Press the power switch for the second power supply to the ON ( | ) position and observe the LEDs on the second power supply faceplate. They should light as described in the previous step.

    If the LEDs are not lit in the appropriate pattern after 60 seconds, repeat the power supply installation procedures in Installing a DC Power Supply and the cable attachment steps in this section.

    Note: When two power supplies are installed, at least one Routing Engine and one FPC must also be installed for both power supplies to power on. In the absence of this minimum load, only one power supply starts. (The router powers on and operates correctly with one power supply, but without the redundancy benefit of a second power supply.)

20. On the external management device connected to the master Routing Engine, monitor the startup process to verify that the system has booted properly.

Figure 75: Connecting DC Power and Grounding Cables