Connecting Power to a Three-Input 240-A Power Supply In 2-INPUT Mode in a TX Matrix Router

1. 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. 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. Verify that the input mode switch is correctly set to 2-INPUT mode. See Setting the Input Mode Switch on a Three-Input 240-A DC Power Supply for the TX Matrix Router.
4. Replace the cable restraint, if needed. See Replacing a Cable Restraint on a TX Matrix Three-Input 240-A DC Power Supply.
5. Switch the circuit breakers on the power supply faceplate to the OFF position (O).
6. Remove the clear plastic cover protecting the terminal studs on the faceplate.
7. Remove the nut and washer from the power terminal studs for INPUT O and INPUT 1. INPUT 2 is not supported for the TX matrix router. If no washers and nuts are already installed, they should be in the accessory box.
8. Secure the cable lug on the DC power cable to the terminal studs for INPUT O and INPUT 1, first with a washer, then with a nut (see Figure 1):
   1. Attach the positive (+) DC source power cable lugs to the RTN (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 (see Connect DC Power to the Two-Input 160-A DC Power Supplies). Apply between 23 lb-in. (2.6 Nm) and 25 lb-in. (2.8 Nm) of torque to each nut.

   Caution: Each power supply must be connected to one dedicated DC power source for each set of return and input terminals.

   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.

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

Figure 1: Connecting DC Power to a Three-Input 240-A Power Supply in Two-Input Mode