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Connecting the EX4650 to Power

Connect the EX4650 Switch to Earth Ground

Before you connect earth ground to a EX4650 switch, ensure that you have the following parts and tools available:

  • Grounding cable:

    • 14 AWG (1.5 mm²), minimum 90° C wire, or as permitted by the local code—not provided

  • Grounding lug:

    • Panduit LCD10-10A-L or equivalent—not provided

  • Screws to secure the grounding lug:

    • 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 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 install the switch in a restricted-access location and ensure that the chassis is properly grounded at all times.

EX4650 switches have one 2-hole protective earthing terminal on the left panel. The preferred method to ground the EX4650 chassis is to use the protective earthing terminal on the switch chassis. Alternatively, you can use any additional grounding method, such as the grounding wire in the AC power cord if it is available. EX4650 switches are tested to meet or exceed all applicable EMC regulatory requirements with the 2-hole protective grounding terminal connected correctly as described in this topic.

CAUTION:

Ensure that a licensed electrician has attached the 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 EX4650 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 23 in. (58.5 cm) through 30.25 in. (76.8 cm). The protective earthing terminal on EX4650 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 25 in. (63.5 cm) through 32.25 in. (81.9 cm). AC-powered switches gain 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. For DC-powered EX4650 switches, if you are unable to access the protective earthing terminal, you can connect the grounding cable to the earth ground terminal on the DC power supply.

To ground the EX4650:

  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. The protective earthing terminal is located on the left panel (see Figure 1).
    Figure 1: Connect a Grounding Cable to the EX4650Connect a Grounding Cable to the EX4650
  3. Secure the grounding lug to the protective earthing terminal with the 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.

Connecting AC Power to an EX4650 Switch

Ensure that you have a power cord appropriate for your geographical location available to connect AC power to the switch.

Before you begin connecting AC 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.

    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. For instructions on connecting earth ground, see Connecting Earth Ground to an EX4650. 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.

The EX4650 is shipped with two 650 W power supplies pre-installed. 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 replacement power supplies in the two slots next to the fan modules without powering off the switch or disrupting switch functions.

To connect AC power to an EX4650:

  1. Attach the grounding strap to your bare wrist and 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 blank cover panel 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. Connect each power supply to the power sources. Insert the coupler end of the power cord into the AC power cord inlet on the AC power supply faceplate.
  5. Push the power cord retainer onto the power cord (see Figure 2).
    Figure 2: Connecting an AC Power Cord to an AC Power Supply in an EX4650Connecting an AC Power Cord to an AC Power Supply in an EX4650
      1

    Power cord retainer

     
  6. The switch powers on as soon as power is provided to the power supply. There is no power switch on the device.
  7. Insert the power cord plug into an AC power source outlet.
  8. Verify that the AC and DC LEDs on each power supply are lit green.

    If the amber fault LED is lit, remove power from the power supply, and replace the power supply. Do not remove the power supply until you have a replacement power supply ready: the power supplies or a blank cover panel must be installed in the switch to ensure proper airflow.

    CAUTION:

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

Connecting DC Power to an EX4650 Switch

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.

    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. For instructions on connecting earth ground, see Connecting Earth Ground to an EX4650.

  • Install the power supply in the chassis.

Ensure that you have the following parts and tools available. Also, the grounding cable must be 14 AWG (2 mm²), minimum 90° C wire, or as permitted by the local code.

  • Grounding lug for your grounding cable—The grounding lug required is a Panduit LCD10-10A-L or equivalent.

  • • Two M4 HEX nuts with integrated washers—Two nuts and washers are used to secure the grounding lug to the grounding lug bracket protective earthing terminal. Four nuts are provided in the accessory kit.

  • • 7-mm wrench or a socket with driver to attach the two nuts.

The EX4650 is shipped from the factory with two 650 W power supplies. 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 replacement power supplies in the two slots next to the fan modules without powering off the switch or disrupting the switching function.

Warning:

A DC-powered EX4650 is intended for installation only in a restricted access location.

Note:

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

To connect DC power to a EX4650:

  1. Attach the grounding strap to your bare wrist and 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 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 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 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 (see Figure 3).
  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 (seeFigure 3 and Figure 4).

    The EX4650 is designed to operate with a DC power supply that has a single, non-redundant, feed input. For source redundancy, two DC power supplies must be installed in the EX4650; 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 in-lb (0.56 Nm) and 6 in-lb (0.68 Nm) of torque to the screws.
    Figure 3: DC Power Supply Faceplate for an EX4650DC Power Supply Faceplate for an EX4650
      1

    Shunt negative input terminals (+RTN)

      5

    ESD grounding point

      2

    Shunt positive input terminals (-48V)

      6

    Fault LED

      3

    Terminal block

      7

    Output LED

      4

    Ejector lever

      8

    Input LED

    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 4: Securing Ring Lugs to the Terminals on the EX4650 DC Power SupplySecuring Ring Lugs to the Terminals on the EX4650 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 device.

  10. Verify that the IN and OUT LEDs on the power supply are lit green and are on steadily.