Connecting Power to a DC-Powered MX80 Router
 | Caution: Do not mix AC and DC power supplies within the same router. Damage to the router might occur. |
 | Warning: Before performing DC power procedures, ensure that power is removed from the DC circuit. To ensure that all power is off, locate the circuit breaker on the panel board that services the DC circuit, switch the circuit breaker to the off position, and tape the switch handle of the circuit breaker in the off position. |
You connect DC power to the router by attaching power cables from the external DC power sources to the terminal on the power supply faceplate. You must provide the power cables (the cable lugs are supplied with the router). For power cable specifications, see DC Power Cable Specifications for the MX80 Router.
To connect the DC source power cables to the router for each power supply:
- 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.
- Attach an electrostatic discharge (ESD) grounding strap to your bare wrist, and connect the strap to one of the ESD points on the chassis.
- Switch the DC circuit breaker on the power supply faceplate to the off (O) position.
- Remove the clear plastic cover protecting the terminal on the faceplate.
- 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.
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.
- Remove the screws from the terminals.
- Secure each power cable lug to the terminal with
the screw (see Figure 1).
Apply between 5 lb-in. (0.6 Nm) and 6 lb-in. (0.7 Nm) of torque to
screw. Do not overtighten the nut. (Use a number 2 Phillips screwdriver.)
- Secure the positive (+) DC source power cable lug to the RTN (return) terminal.
- 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: 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.
Note: For information about connecting to DC power sources, see MX80 Router DC Power Specifications.
- Replace the clear plastic cover over the terminals on the faceplate.
- Verify that the power cables are connected correctly, that they are not touching or blocking access to router components, and that they do not drape where people could trip on them.
- If you are installing two power supplies, repeat Steps 3 through 9 for the other power supply.
Figure 1: Connecting DC Power to the Router
