Replacing a DC Power Supply on the SRX550 Services Gateway

You can replace the DC power supply on the SRX550 Services Gateway after disconnecting the power cord and removing the power supply already installed. However, redundant DC power supplies are hot-swappble. You need not power off the services gateway for replacing them.

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

This topic describes:

Removing a DC Power Supply from the SRX550 Services Gateway

Up to two power supplies can be installed at the rear of the chassis on the right side. Each DC power supply weighs approximately 2 lb (1.29 kg).

Caution: Do not leave a power supply slot empty for more than 30 minutes while the services gateway is operational. For proper airflow, the power supply must remain in the chassis, or a blank panel must be used in an empty slot.

Note: After powering off a power supply, wait at least 60 seconds before turning it back on.

To remove a DC power supply, see Figure 30.

  1. Switch off the dedicated facility circuit breaker for the power supply. Follow the electrostatic discharge (ESD) and disconnection instructions for your site.
  2. Make sure that the voltage across the DC power source cable leads is 0 V and that there is no chance that the cables might become active during the removal process.
  3. Attach an ESD grounding strap to your bare wrist and connect the strap to one of the ESD points on the chassis. For more information about ESD, see Preventing Electrostatic Discharge Damage to the SRX550 Services Gateway.
  4. Remove the clear plastic cover protecting the terminal studs on the faceplate.
  5. Remove the screws and washers from the terminals. Use a Phillips (+) screwdriver, number 2 to loosen and remove the screws.
  6. Remove the cable lugs from the terminal studs.
  7. Carefully move the power cables out of the way.
  8. Push the tab on the left edge of the power supply to the right.
  9. Pull the power supply straight out of the chassis.

Figure 30: Removing a DC Power Supply from the SRX550 Services Gateway

Removing a DC
Power Supply from the SRX550 Services Gateway

Installing a DC Power Supply on the SRX550 Services Gateway

To install a DC power supply:

  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. To ensure that all power is off, locate the circuit breaker on the panel board that services the DC circuit, switch the circuit breaker to off position (O), and tape the switch handle of the circuit breaker in the off position.
  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. For more information about ESD, see Preventing Electrostatic Discharge Damage to the SRX550 Services Gateway.
  3. Orient the power supply so that the locking lever is on the left, as shown in Figure 31.

    Figure 31: Installing a DC Power Supply on an SRX550 Services Gateway

    Installing a DC Power
Supply on an SRX550 Services Gateway
  4. Using both hands, slide the power supply straight into the chassis until the power supply is fully seated in the chassis slot. The power supply faceplate should be flush with any adjacent power supply faceplate.
  5. Tighten the captive screws on the lower edge of the power supply faceplate.
  6. Remove the clear plastic cover protecting the terminal studs on the faceplate.
  7. 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 large resistance (indicating an open circuit) to chassis ground will be –48V.
    • The cable with very low resistance (indicating a closed circuit) to chassis ground will be RTN.

    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 terminals on the power supply.

  8. Connect DC power cables to the A+ and A- terminals:
    1. Remove the screws and square washers from the A+ and A- terminals. Use a Phillips (+) screwdriver, number 2. The square washers are permanently attached to the screws.
    2. Secure each power cable lug to the appropriate terminal with a screw. Apply between 23 lb-in. (2.6 Nm) and 25 lb-in. (2.8 Nm) of torque to each screw.
      • Secure the positive (+) DC source power cable lug to the A+ (return) terminal.
      • Secure the negative (–) DC source power cable lug to the A- (input) terminal.

    Figure 32: Connecting DC Power Cables

    Connecting DC Power Cables
  9. Replace the clear plastic cover over the terminal studs on the faceplate.
  10. Verify that the power cables are connected correctly, that they are not touching or blocking access to services gateway components, and that they do not drape where people could trip on them.
  11. Remove the tape from the switch handle of the circuit breaker on the panel board that services the DC circuit and switch the circuit breaker to the on position (  |  ). Observe the status LEDs on the power supply faceplate. If the power supply is correctly installed and functioning normally, the POWER LED lights green steadily on the services gateway front panel.

Note: If more than one power supply is being installed, turn on all power supplies at the same time.

Removing a DC Power Supply Cable from the SRX550 Services Gateway

To remove a power supply cable connected to a DC power supply:

  1. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist and connect the strap to an approved site ESD grounding point. For more information about ESD, see Preventing Electrostatic Discharge Damage to the SRX550 Services Gateway.
  2. Switch off the external circuit breakers for all the cables attached to the power supply. Make sure that the voltage across the DC power source cable leads is 0 V and that there is no chance that the cables might become active during the removal process.
  3. Remove the power cable from the DC power source.
  4. Attach an ESD grounding strap to your bare wrist and connect the strap to one of the ESD points on the chassis. For more information about ESD, see Preventing Electrostatic Discharge Damage to the SRX550 Services Gateway.
  5. Make sure the cable is not touching or in the way of any services gateway components and that it does not drape where people could trip on it.
  6. Remove the clear plastic cover protecting the terminal studs on the faceplate.
  7. Attach the power cable to the DC power source.
  8. Verify that the DC source power cabling is correct. If the power cable is correctly installed and the power supply is functioning normally, the POWER LED on the front panel lights green steadily.

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