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    Connect Power Cables

    The DC power supply has four terminals on the front panel, covered by a clear plastic cover.

    Warning: You must ground the router before connecting the DC power cables.

    Table 1: ACX2000 DC Power System Input Voltage

    Nominal Voltage



    Operating range: +18 to +30 VDC


    Operating range: –39 to –56 VDC


    Operating range: –39 to –72 VDC

    1. Switch off the dedicated customer site circuit breakers. 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. Remove the clear plastic cover protecting the terminal on the faceplate.
    3. Verify that the DC power cables are correctly labeled before making connections to the power supply. In a typical power distribution scheme where the return is connected to chassis ground at the battery plant, you can use a multimeter to verify the resistance of the –48V and RTN DC cables to chassis ground:
      • The cable with very large resistance (indicating an open circuit) to chassis ground is –48V.
      • The cable with very low resistance (indicating a closed circuit) to chassis ground is RTN.
    4. Remove the screws and flat washers from the terminals.
    5. Secure each power cable lug to the terminal with the flat washers and screw (see Figure 8). Apply between 8 lb-in. (0.9 Nm) and 9 lb-in. (1.02 Nm) of torque to each screw. Do not overtighten the screw. (Use a number 2 Phillips screwdriver.)
      1. Secure the positive (+) DC source power cable lug to the RTN (return) terminal.
      2. Secure the negative (–) DC source power cable lug to the –48V (input) terminal.

      Caution: Ensure that each power cable lug seats flush against the surface of the terminal block as you are tightening the screws. Ensure that each screw is properly threaded into the terminal. Applying installation torque to the screw when improperly threaded may result in damage to the terminal.

      Caution: The maximum torque rating of the terminal screws on the DC power supply is 9 lb-in. (1.02 Nm). The terminal screws may be damaged if excessive torque is applied. Use only a torque-controlled driver to tighten screws on the DC power supply terminals. Use an appropriately-sized driver, with a maximum torque capacity of 9 lb-in. or less. Ensure that the driver is undamaged and properly calibrated and that you have been trained in its use. You may wish to use a driver that is designed to prevent overtorque when the preset torque level is achieved.

    6. Replace the clear plastic cover over the terminals on the faceplate.
    7. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist, and connect the strap to an approved site ESD grounding point. See the instructions for your site.
    8. Connect each DC power cable to the appropriate external DC power source.

      Note: For information about connecting to external DC power sources, see the instructions for your site.

    9. Switch on the external circuit breakers to provide voltage to the DC power source cable leads. Observe the system LED on front of the router. If the DC power cable is correctly installed and functioning normally, the system LED lights green steadily. If the status LED indicates that the power supply is not functioning normally, repeat the installation and cabling procedures.

    Figure 8: Connecting DC Power to the Router

    Connecting DC Power
to the Router

    Modified: 2016-04-11