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Connect the QFX5120 to Power

 

Connect the QFX5120 Switch to Earth Ground

To ensure proper operation and to meet safety and electromagnetic interference (EMI) requirements, you must connect the switch to earth ground before you connect power to the switch. You must use the protective earthing terminal on the switch chassis to connect the switch to ground.

Note

A ground connection to the protective earthing terminal is not required for an AC-powered switch. The AC power cords provide adequate grounding when you connect the power supply in the switch to a grounded AC power outlet by using the AC power cord appropriate for your geographical location.

Warning

The switch is installed in a restricted-access location.

Caution

If an external ground connection is required, ensure that a licensed electrician has attached an appropriate grounding lug to the grounding cable that you supply. Using a grounding cable with an incorrectly attached lug can damage the switch.

Note

The protective earthing terminal on QFX5120-48Y or QFX5120-48T switches mounted flush with the front posts of a rack is accessible through the slot on the left rear bracket only if the distance between the front posts and the rear posts is between 27.50 in. (69.9 cm) and 30.5 in. (77.5 cm). The protective earthing terminal on QFX5120-48Y or QFX5120-48T switches mounted in a recessed position from the front posts of a rack is accessible through the slot on the left rear bracket only if the distance between the front posts and the rear posts is between 29.50 in. (75 cm) and 32.5 in. (82.6 cm).

Before you begin connecting earth ground to a QFX5120 switch, ensure that you have the following parts and tools available:

  • Grounding cable

    • QFX5120-32C: 12 AWG (1.5 mm²), minimum 90° wire, or as permitted by the local code—not provided

    • QFX5120-48Y and QFX5120-48T: 14 AWG (2 mm²), minimum 90° C wire, or as permitted by the local code—not provided

  • Grounding lug

    • QFX5120-32C: 4.3-mm circular lug—not provided

    • QFX5120-48Y and QFX5120-48T: Panduit LCD10-10A-L or equivalent—not provided

  • Screws to secure grounding lug

    • QFX5120-32C: 8-mm screw—not provided

    • QFX5120-48Y and QFX5120-48T: Two 10-32 x .25 in. screws with #10 split-lock washers—not provided

  • Number 2 Phillips (+) screwdriver—not provided

  • ESD grounding strap—not provided

To ground the QFX5120:

  1. Connect one end of the grounding cable to a proper earth ground, such as the rack in which the switch is mounted.
  2. Place the grounding lug attached to the grounding cable over the protective earthing terminal (see Figure 1 and Figure 2). The protective earthing terminal is on the rear panel on a QFX5120-32C switch and on the left panel on a QFX5120-48Y switch and a QFX5120-48T switch.
    Figure 1: Connect a Grounding Cable to a QFX5120-32C Switch
    Connect a Grounding Cable
to a QFX5120-32C Switch
    Figure 2: Connect a Grounding Cable to a QFX5120-48Y or QFX5120-48T Switch
    Connect
a Grounding Cable to a QFX5120-48Y or QFX5120-48T Switch
  3. Secure the grounding lug to the protective earthing terminal with the washers and screws.
  4. Dress the grounding cable and ensure that it does not touch or block access to other switch components.Warning

    Ensure that the cable does not drape where people could trip over it.

Connect Power to an AC-Powered QFX5120 Switch

We ship the QFX5120 switches with two power supplies preinstalled. Each power supply is a hot-removable and hot-insertable field-replaceable unit (FRU) when the second power supply is installed and running: You can install power supplies in the slots next to the fan modules without powering off the switch or disrupting switch functions.

Before you begin connecting AC power to the switch:

  • Ensure that you have a power cord appropriate for your geographical location available.

  • Ensure that you have the power cord retainer shipped with the switch.

  • Ensure that you have taken the necessary precautions to prevent electrostatic discharge (ESD) damage (see Prevention of Electrostatic Discharge Damage).

  • 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 the chassis to earth ground before you connect it to power (see Connect the QFX5120 Switch to Earth Ground). For installations that require a separate grounding conductor to the chassis, use the protective earthing terminal on the switch chassis to connect to earth ground. The switch gains additional grounding when you plug the power supply in the switch into a grounded AC power outlet by using the AC power cord appropriate for your geographical location.

To connect power to an AC-powered QFX5120 switch:

  1. Wrap and fasten one end of the ESD wrist strap around your bare wrist, and connect the other end of the strap to a site ESD point.
  2. Ensure that the power supplies are fully inserted in the chassis and the latches are secure. If only one power supply is installed, ensure that a cover is installed over the second power supply slot.
  3. Locate the power cord or cords shipped with the switch; the cords have plugs appropriate for your geographical location.Warning

    Ensure that the power cord does not block access to device components or drape where people can trip on it.

  4. Push the end of the retainer strip into the hole next to the inlet on the power supply face plate until it snaps into place. Ensure that the loop in the retainer strip faces the power cord.
  5. Press the small tab on the retainer strip to loosen the loop. Slide the loop until you have enough space to insert the power cord coupler into the inlet.
  6. Insert the power cord coupler firmly into the inlet.
  7. Slide the loop toward the power supply until it is snug against the base of the coupler.
  8. Press the tab on the loop and draw out the loop into a tight circle (see Figure 3 and Figure 4).
    Figure 3: Connect Power to an AC-Powered QFX5120-32C Switch
    Connect Power to
an AC-Powered QFX5120-32C Switch
    Figure 4: Connect Power to an AC-Powered QFX5120-48Y or QFX5120-48T Switch
    Connect
Power to an AC-Powered QFX5120-48Y or QFX5120-48T Switch
  9. If the AC power source outlet has a power switch, set it to the off position.Note

    The switch powers on as soon as power is provided to the power supply. There is no power switch on the QFX5120.

  10. Insert the power cord plug into an AC power source outlet.
  11. If the AC power source outlet has a power switch, set it to the on position.
    • If you are connecting the power supply in a QFX5120-32C switch, verify that the LED on the power supply is lit green. If the LED is lit or blinking red, disconnect the power supply from the power source, and replace the power supply (see Remove a Power Supply from a QFX5120 Switch).

    • If you are connecting the power supply in a QFX5120-48Y or QFX5120-48T switch, verify that the AC and DC LEDs on the power supply are lit green. If the fault LED (!) is lit, disconnect the power supply from the power source, and replace the power supply (see Remove a Power Supply from a QFX5120 Switch).

    Do not remove the power supply until you have a replacement power supply ready: you must install the power supplies or a cover in the switch to ensure proper airflow.Caution

    Replace a failed power supply with a cover or a new power supply within one minute of removal to prevent chassis overheating.

Connect Power to a DC-Powered QFX5120 Switch

We ship the QFX5120 switches with two power supplies preinstalled. Each power supply is a hot-removable and hot-insertable field-replaceable unit (FRU) when the second power supply is installed and running: You can install power supplies in the slots next to the fan modules without powering off the switch or disrupting switch functions.

Note

The battery returns of the DC power supply must be connected as an isolated DC return (DC-I).

Before you begin connecting DC power to the switch:

  • Ensure that you have taken the necessary precautions to prevent electrostatic discharge (ESD) damage (see Prevention of Electrostatic Discharge Damage).

  • Ensure that you have connected the switch chassis to earth ground (see Connect the QFX5120 Switch 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 the chassis to earth ground before you connect it 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.

Ensure that you have the following parts and tools available:

  • For the DC-powered models QFX5120-32C-DC-AFO and QFX5120-32C-DC-AFI—DC power cable with a plug—provided

  • For the DC-powered models QFX5120-48Y-DC-AFO2, QFX5120-48Y-DC-AFI2, QFX5120-48T-DC-AFO, and QFX5120-48T-DC-AFI: DC power source cables (14–16 AWG) with ring lug (Molex 190700069 or equivalent)—not provided

  • Number 2 Phillips (+) screwdriver—not provided

  • Multimeter—not provided

To connect power to a DC-powered QFX5120-32C switch:

  1. Wrap and fasten one end of the ESD wrist strap around your bare wrist, and connect the other end of the strap to a site ESD point.
  2. 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 do not become active while you are connecting DC power.
  3. Ensure that the power supplies are fully inserted in the chassis.
  4. Connect each power supply to the power source by inserting the DC connector of the provided power cable into the power supply (see Figure 5).
    Figure 5: Connect Power to a DC-Powered QFX5120-32C Switch
    Connect
Power to a DC-Powered QFX5120-32C Switch
  5. Connect each power cable to the power sources. Secure power source cables to the power supplies by screwing the ring lugs attached to the cables to the appropriate terminals.
    • Connect the ring lug of the green-yellow cable to earth ground.

    • Connect the ring lug of the black cable to the negative (–) DC power source.

    • Connect the ring lug of the red cable to the positive (+) DC power source.

    The QFX5120-32C is designed to operate with a DC power supply that has a single, nonredundant, feed input. For source redundancy, you must install two DC power supplies in the QFX5120-32C; connect source (A) to one power supply and connect source (B) to the second power supply. This configuration provides the commonly deployed A/B feed redundancy for the system.

    Caution

    The connection between each power source and power supply must include a circuit breaker. Do not connect two sources to a single power supply because doing so can potentially cause circulating current in feed wires whenever there is any difference in the voltage of the two sources.

  6. Close the input circuit breaker.Note

    The switch powers on as soon as power is provided to the power supply. There is no power switch on the QFX5120.

  7. Verify that the LED on the power supply is lit green. If the LED is lit or blinking red, disconnect the power supply from the power source, and replace the power supply (see Remove a Power Supply from a QFX5120 Switch).

    Do not remove the power supply until you have a replacement power supply ready: you must install the power supplies or a cover in the switch to ensure proper airflow.

    Caution

    Replace a failed power supply with a cover or a new power supply within one minute of removal to prevent chassis overheating.

To connect DC power to a QFX5120-48Y or QFX5120-48T switch:

  1. Wrap and fasten one end of the ESD wrist strap around your bare wrist, and connect the other end of the strap to a site ESD point.
  2. 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 low resistance (indicating a closed circuit) to chassis ground is positive (+) and will be installed on the V+ (return) DC power input terminal.

    • The cable with very high resistance (indicating an open circuit) to chassis ground is negative (–) and will be installed on the V– (input) DC power input 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 coding for DC power cables. The coding used by the external DC power source at your site determines the coding for the leads on the power cables that attach to the DC power input terminals on each power supply.

  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 do not become active while you are connecting DC power.Note

    The V+ terminals are referred to as +RTN, and the V– terminals are referred to as –48 V in DC Power Wiring Sequence Warning and DC Power Electrical Safety Guidelines.

  4. Ensure that the power supplies are fully inserted in the chassis.
  5. Remove the terminal block cover. The terminal block cover is a piece of clear plastic that snaps into place over the terminal block.
  6. Remove the screws on the terminals using the screwdriver. Save the screws.Warning

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

  7. Connect each power supply to the power sources. Secure power source cables to the power supplies by screwing the ring lugs attached to the cables to the appropriate terminals by using the screw from the terminals (see Figure 6).

    We’ve designed the QFX5120-48Y or QFX5120-48T switch to operate with a DC power supply that has a single, nonredundant, feed input. For source redundancy, you must install two DC power supplies in the QFX5120-48Y or QFX5120-48T switch; connect source (A) to one power supply and connect source (B) to the second power supply. This configuration provides the commonly deployed A/B feed redundancy for the system.

    The terminal block of the power supply has four terminals labeled V+, V+, V–, and V– for connecting DC power source cables labeled positive (+) and negative (–). The V+ terminals are shunted internally together, as are the V– terminals.

    Caution

    The connection between each power source and power supply must include a circuit breaker.

    Do not connect two sources to a single power supply because doing so can potentially cause circulating current in feed wires whenever there is any difference in the voltage of the two sources.

    1. Secure the ring lug of the positive (+) DC power source cable to the V+ terminal on the DC power supply.
    2. Secure the ring lug of the negative (–) DC power source cable to the V– terminal on the DC power supply.
    3. Tighten the screws on the power supply terminals until snug using the screwdriver. Do not overtighten; apply between 5 lb-in. (0.56 Nm) and 6 lb-in. (0.68 Nm) of torque to the screws.
    Caution

    The V+ terminals are shunted internally together, as are the V- terminals. The same polarity terminal can be wired together from the same source to provide an additional current path in a higher power chassis. Do not connect the terminals to different sources.

    Figure 6: Secure Ring Lugs to the Terminals on the QFX5120-48Y or QFX5120-48T DC Power Supply
    Secure
Ring Lugs to the Terminals on the QFX5120-48Y or QFX5120-48T DC Power
Supply
  8. Replace the terminal block cover.
  9. Close the input circuit breaker.Note

    The switch powers on as soon as power is provided to the power supply. There is no power switch on the QFX5120.

  10. Verify that the IN and OUT LEDs on the power supply are lit green. If the fault LED (!) is lit, disconnect the power supply from the power source, and replace the power supply (see Remove a Power Supply from a QFX5120 Switch).

    Do not remove the power supply until you have a replacement power supply ready: you must install the power supplies or a cover in the switch to ensure proper airflow.

    Caution

    Replace a failed power supply with a cover or a new power supply within one minute of removal to prevent chassis overheating.

Connect Power to a QFX5120-48T Switch Powered by a High-Voltage Power Supply

We ship the QFX5120 switches with two AC or DC power supplies preinstalled. You must order a high-voltage power supply separately. Each power supply is a hot-removable and hot-insertable field-replaceable unit (FRU) when the second power supply is installed and running: You can install power supplies in the slots next to the fan modules without powering off the switch or disrupting switch functions.

Before you begin connecting power to a QFX5120-48T switch powered by a high-voltage power supply:

  • Ensure that you have a power cord appropriate for your geographical location and power input available. You must order the power cord separately.

  • Ensure that you have taken the necessary precautions to prevent electrostatic discharge (ESD) damage (see Prevention of Electrostatic Discharge Damage).

  • 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 the chassis to earth ground before you connect it to power (see Connect the QFX5120 Switch to Earth Ground). For installations that require a separate grounding conductor to the chassis, use the protective earthing terminal on the switch chassis to connect to earth ground. The switch gains additional grounding when you plug the power supply in the switch into a grounded AC power outlet by using the AC power cord appropriate for your geographical location.

To connect power to a QFX5120-48T switch powered by a high-voltage power supply:

  1. Wrap and fasten one end of the ESD wrist strap around your bare wrist, and connect the other end of the strap to a site ESD point.
  2. Ensure that the power supplies are fully inserted in the chassis and the latches are secure. If only one power supply is installed, ensure that a cover is installed over the second power supply slot.
  3. Locate the power cord appropriate for your geographical location and power input.Warning

    Ensure that the power cord does not block access to device components or drape where people can trip on it.

  4. Insert the coupler end of the power cord into the power cord inlet on the power supply faceplate (see Figure 7).
    Figure 7: Connect Power to a QFX5120-48T Switch Powered by a High-Voltage Power Supply
    Connect
Power to a QFX5120-48T Switch Powered by a High-Voltage Power Supply
    Note

    The switch powers on as soon as power is provided to the power supply. There is no power switch on the QFX5120.

  5. Connect power to the switch:

    • AC power input:

      1. If the AC power source outlet has a power switch, set it to the off position.
      2. Insert the power cord plug into an AC power source outlet.
      3. If the AC power source outlet has a power switch, set it to the on position.

      DC power input:

      1. Switch the circuit breaker on the panel board that services the DC circuit to the off position.
      2. Connect the power cables to the terminals on the power source.
      3. Close the input circuit breaker.
  6. Verify that the AC and DC LEDs on the power supply are lit green. If the fault LED (!) is lit, disconnect the power supply from the power source, and replace the power supply (see Remove a Power Supply from a QFX5120 Switch).