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Connecting DC Power to an EX 3200 or EX 4200 Switch

The power supply in an EX 3200 or EX 4200 switch is a hot-removable and hot-insertable field-replaceable unit (FRU) located on the rear panel.

Figure 1: DC Power Supply in EX 3200 and EX 4200 Switches

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Warning: DC-powered EX 3200 and EX 4200 switches are intended for installation only in a restricted access location.

Ensure that you have the following parts and tools available to connect DC power to an EX 3200 or EX 4200 switch:

  • Electrostatic discharge (ESD) grounding strap
  • DC power source cables (12–14 AWG) with ring lug (Molex 190700067 or equivalent) (not provided)
  • Phillips (+) screwdriver, number 2

Before you begin connecting DC power to an EX 3200 or EX 4200 switch:

  • Ensure that you have taken the necessary precautions to prevent ESD damage (see Prevention of Electrostatic Discharge Damage on EX-series Switches).
  • Ensure that you have connected the switch chassis to earth ground.

    Caution: Before you connect power to the switch, a licensed electrician must attach a cable lug to the grounding and power cables that you supply. A cable with an incorrectly attached lug can damage the switch (for example, by causing a short circuit).

    To meet safety and electromagnetic interference (EMI) requirements and to ensure proper operation, you must connect EX 3200 and EX 4200 switches to earth ground before you connect them to power. For installations that require a separate grounding conductor to the chassis, use the protective earthing terminal on the switch chassis to connect to the earth ground. For instructions on connecting earth ground, see Connecting Earth Ground to an EX-series Switch.

  • Install the power supply in the chassis. For instructions on installing a power supply in an EX 3200 or EX 4200 switch, see Installing a Power Supply in an EX 3200 or EX 4200 Switch.

To connect DC power to an EX 3200 or EX 4200 switch:

  1. Attach the electrostatic discharge (ESD) grounding strap to your bare wrist, and connect the strap to the ESD point on the chassis.
  2. Ensure that the power supplies are fully inserted in the chassis and the screws on their faceplates are tightened.
  3. Ensure that the input circuit breaker is open so that the voltage across the DC power source cable leads is 0 V and that the cable leads will not become active while you are connecting DC power.

    Note: The DC power supply in EX 3200 and EX 4200 switches has four terminals labeled A+, A–, B+, and B– (see Figure 1) for connecting DC power source cables labeled positive (+) and negative (–). The DC power supplies for EX 3200 and EX 4200 switches are shipped with jumpers from A+ input to B+ input tied together and jumpers from A– input to B– input tied together.

    Note: The A+ and B+ terminals are referred to as +RTN and A– and B– terminals are referred to as –48 V in DC Power Wiring Sequence Warning for EX 3200 and EX 4200 Switches and DC Power Electrical Safety Guidelines for EX 3200 and EX 4200 Switches.

  4. Remove the screw securing the terminal block cover using the Phillips (+) screwdriver, number 2 and remove the terminal block cover (see Figure 2). Save the screw.

    Figure 2: Removing the Terminal Block Cover in a DC Power Supply in EX 3200 and EX 4200 Switches

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  5. Remove the screws on the terminals using the Phillips (+) screwdriver, number 2. Save the screws.

    Warning: Ensure that the power cables do not block access to switch components or drape where people can trip on them.

  6. Connect the power supplies to the power sources. Secure power source cables to the power supplies by screwing the ring lug attached to the cable to the appropriate terminal by using the screw from the terminal (see Figure 3).
    • To connect a power supply to a power source:
      1. Leave the jumpers on the power supply terminals in place.
      2. Secure the ring lug of the positive (+) DC power source cable to the A+ or B+ terminal on the DC power supply.
      3. Secure the ring lug of the negative (–) DC power source cable to the A– or B– terminal on the DC power supply.
      4. Tighten the screws on the power supply terminals until snug using the Phillips (+) screwdriver, number 2. Do not overtighten—apply between 8 lb-in. (0.9 Nm) and 9 lb-in. (1.02 Nm) of torque to the screws.

      If you have a second installed power supply, connect it in the same way you did the first.

    • To connect one power supply to two power sources:
      1. Remove the jumpers on the power supply terminal block.
      2. Secure the ring lug of the positive (+) DC power source cable from the first DC power source to the A+ terminal on the first DC power supply.
      3. Secure the ring lug of the negative (–) DC power source cable from the first DC power source to the A– terminal on the first DC power supply.
      4. Secure the ring lug of the positive (+) DC power source cable from the second DC power source to the A+ terminal on the second DC power supply.
      5. Secure the ring lug of the negative (–) DC power source cable from the second DC power source to the A– terminal on the second DC power supply.
      6. Tighten the screws on the power supply terminals on both the power supplies until snug using the Phillips (+) screwdriver, number 2. Do not overtighten—apply between 8 lb-in. (0.9 Nm) and 9  lb-in. (1.02 Nm) of torque to the screws.

    Figure 3: Securing Ring Lugs to the Terminals on the DC Power Supply in EX 3200 and EX 4200 Switches

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  7. Replace the terminal block cover and secure it using the screw. Use the Phillips (+) screwdriver, number 2 to tighten the screw.
  8. Close the input circuit breaker.
  9. Verify that the LEDs on the power supply are lit green and are on steadily.

DC Power Supply LEDs in EX 3200 and EX 4200 Switches describes the LEDs on the DC power supplies in EX 3200 and EX 4200 switches.

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