Technical Documentation

Connecting Power to a DC-Powered M7i Router

Connect DC power to the router by inserting power cables into the field-wiring terminals on the faceplate of each power supply. Power and grounding cables are not supplied with the router. For information about the required cable type, see M7i Chassis Grounding, Connection, and Cable Specifications.

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 each power supply. 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 (see Figure 1):

  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 for each external DC power sources, if it is not already.
  4. Verify that a licensed electrician has attached the cable lug provided with the router to the grounding cable.
  5. Using a number 2 Phillips screwdriver, remove the screws next to the grounding symbol above the power supplies on the chassis rear. Secure the grounding cable lug to the chosen grounding point by reinstalling and tightening the screws.
  6. Verify that a licensed electrician has attached a listed power cable lug to each power source cable.
  7. Loop the power cables through the hook located on the faceplate to the right of the field-wiring terminals.
  8. Depending on the type of power cable lugs used, loosen or remove the screws on the field-wiring terminals.
  9. Insert the power cable lugs into the appropriate field-wiring terminals. Using a number 1 Phillips screwdriver, turn the screw on each field-wiring terminal clockwise to secure the power cable lug. Apply between 8 lb-in. (.9 Nm) and 9 lb-in. (1.02 Nm) of torque to each screw.
    1. Insert the positive (+) source cable into the return terminal, which is labeled RTN.
    2. Insert the negative (–) source cable into the input terminal, which is labeled –48V.
  10. Verify that the DC 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.

Figure 1: Connecting DC Power and Grounding Cables

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Published: 2009-08-03