Installing an MX2020 Three-Phase Wye AC Power Distribution Module

Each three-phase wye AC PDM weighs approximately 12 lb (5.44 kg). To install a three-phase wye AC PDM:

Warning: Before performing AC power procedures, disconnect all power sources. To ensure that all power is off, locate the circuit breaker on the panel board that services the AC circuit, switch the circuit breaker to the off position, and tape the switch handle of the circuit breaker in the off position.

Caution: To maintain proper cooling and prevent thermal shutdown of the operating power supply unit, each PDM slot must contain either a PDM or a blank panel. If you remove a PDM, you must install a replacement PDM or a blank panel shortly after the removal.

Note: After powering off a PDM, wait at least 60 seconds before turning the circuit breaker back on.

Note: The PDMs are hot swappable in a redundant configuration. However, you cannot switch from one type of PDU (AC or DC) to another while the system is on.

1. Make sure that the voltage across the AC power source cord is 0 V and that there is no chance that the cord might become active during the installation process.
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. Switch off (O) the AC PSMs and disengage all AC PSMs.
4. Pull the locking levers on either side of the faceplate away until they stop.
5. Using both hands, slide the PDM into the chassis until you feel resistance (see Figure 1).
6. Push the lock levers completely into until they make contact with the PDM faceplate.
7. Tighten the two captive screws on the locking levers of the PDM faceplate to secure the PDM in the chassis.
8. Using a number 2 Phillips (+) screwdriver, loosen the four screws on the cover of the metal wiring compartment that protects the AC terminal block.

   Figure 1: Installing a Three-Phase Wye AC Power Distribution Module

   
9. Remove the cover of the metal AC wiring compartment.
10. Unscrew the retaining nut from the AC power cord.
11. Place the retaining nut inside the metal wiring compartment.
12. Put the wires of the AC power cord through the hole of the retaining nut and rubber grommet.
13. Put the wires of the AC power cord through the hole of the metal wiring compartment.
14. Connect the wires to the AC terminal block on the three-phase delta AC PDM (see Figure 2). Loosen each of the input terminals or grounding point screws, and insert the wire into the grounding point or input terminal, and tighten the screw (see Table 1 for approved AC wire gauge).

    To insert wires into the terminal block that serves six PSMs:

    1. Insert the grounding wire into the grounding point labeled GND.
    2. Insert the wire labeled L1 into the input terminal labeled A1.
    3. Insert the wire labeled L2 into the input terminal labeled B1.
    4. Insert the wire labeled L3 into the input terminal labeled C1.
    5. Insert the wire labeled N into the input terminal labeled N1.

    Figure 2: Connecting Power to a Three-Phase Wye AC Power Distribution Module

    

    Note: The three-phase wye AC PDM terminal blocks will be flipped depending on which slot the PDM gets plugged into.

    Note: The color of each AC power wire might vary. The MX2020 chassis is not sensitive to phase rotation sequence—either CW or CCW will operate correctly.

    Caution: Wire label configuration is for Juniper Networks supplied cable only. If using your own cable, make sure you use the proper connections.

    To insert wires into the terminal block that serves three PSMs:

    1. Insert the grounding wire into the grounding point labeled GND.
    2. Insert the wire labeled L1 into the input terminal labeled A2.
    3. Insert the wire labeled L2 into the input terminal labeled B2.
    4. Insert the wire labeled L3 into the input terminal labeled C2.
    5. Insert the wire labeled N into the input terminal labeled N2.

    Note: The terminal connections have either slotted screws or hex screws. Use a 1/4-in. slotted screwdriver for the slotted screws. Use a 5/32-in. (4 mm) Allen wrench for the 5/16-in. hex screws.

    Warning: To protect power supplies from input voltage that may be caused by miswired PDMs, before reinstalling the metal cover to the wiring compartment apply AC voltage to the PDM (with disengaged PSM) to make sure that two LEDs on the PDM are lit green and that the AC voltage between AC terminal blocks A1-N1, B1-N1, C1-N1, A2-N2, B2-N2, and C2-N2 for three-phase wye PDM is not more than 264VAC when measured with a DVM. Then turn off the AC breaker de-energizing the PDM and install the metal cover and engage all AC PSMs.

    Note: Three-phase wye AC wire assembly kits can be purchased from Juniper Networks.

    Table 1: Supported Three-Phase Wye AC Wire Gauge

    Wire Gauge	Description
    5 x 10-AWG or equivalent	5 conductor wires, each wire is 10-AWG

    Note: We recommend that you use the proper gauge wire in order for the cable clamps to hold the AC cables. Using smaller gauge wiring will result in the cable clamps not tightening properly.

    Warning: Power connections must be performed by a licensed electrician only.

15. Verify that the power cord wire connections are correct.
16. Screw the retaining nut onto the AC power cord to secure it to the metal wiring compartment.
17. Using a number 2 Phillips (+) screwdriver, tighten the four captive screws on the metal AC wiring compartment.
18. Verify that the AC power cord is not touching or blocking access to router components, and that it does not drape where people could trip on it.
19. Remove the ESD grounding strap from the ESD points on the chassis. Connect the strap to an approved site ESD grounding point. See the instructions for your site.
20. Connect the AC power cord plug to the power source.
21. Switch on the customer site circuit breakers to provide voltage on the AC power cord.
22. Remove the ESD grounding strap from the approved site ESD grounding point. See the instructions for your site. Reconnect the strap to one of the ESD points on the chassis.
23. Verify that the LED on the PDM faceplate is lit steadily, indicating that the AC terminal block is receiving power.
24. Switch the power switches on all the PSMs to the on (|) position to provide power to the router components.