Maintaining the T640 Power Supplies

Purpose

For optimum router performance, verify the condition of the power supplies.

Action

• Make sure that the power and grounding cables are arranged so that they do not obstruct access to other router components.

• The power supplies require an unobstructed airflow at both the front and rear of the chassis. Periodically check the site to ensure that both the air intake at the bottom front of the chassis and the exhaust from the power supply faceplates are unobstructed.

• Periodically inspect the site to ensure that the grounding and power cables connected to the router are securely in place and that no moisture is accumulating near the router. To review grounding and site wiring requirements for the router, see T640 Chassis Grounding Cable and Lug Specifications and Site Electrical Wiring Guidelines for Juniper Networks Devices.

• Regularly inspect the air filters on each power supply for dust and debris, and replace the side filter on AC power supplies or front filter element on AC and DC power supplies every 6 months. To replace a power supply front air filter element, see Replacing a Front Air Filter Element on a T640 AC or DC Power Supply. To replace a side air filter, see Replacing a Side Air Filter on a T640 AC Power Supply .

• Routinely check the LEDs on the DC power supply faceplates.

  For a two-input 160-A DC power supply:

  • The blue DC OK LEDs light to indicate that the power supplies are functioning normally.

  • The CB ON LED is lit, indicating that the circuit breaker is on.

  • For a three-input 240-A DC power supply or four-input 240-A DC power supply:

    • The blue DC OK LED is on, the power source is good and the power supplies are functional.

    • Each INPUT PRESENT LED is lit, indicating that the input is receiving source DC power.

    • The CB ON LED is lit, indicating that the circuit breaker is on.

  • For a six-input DC power supply:

    • The blue DC OK LED is on, the power source is good and the power supplies are functional.

    • Each INPUT PRESENT LED is lit, indicating that the input is receiving source DC power.

• Routinely check the LEDs on the AC power supply faceplates. For a three-phase delta or wye AC power supply:

  • The green AC OK LED lights to indicate that the power supply is receiving source AC power.

  • The blue DC OK LED lights to indicate that the power supply is functioning normally.

• Check the red and yellow alarm LEDs and the LCD on the craft interface. Power supply failure or removal triggers an alarm that causes one or both of the LEDs to light and an error message to appear on the LCD. You can display the associated error messages by issuing the CLI command:

  user@host> show chassis alarms

  For a list of possible alarm messages, see Troubleshooting the T640 Power System.

• Issue the show chassis environment pem command to check the status of the power supplies.

  For further description of the output from the commands, see show chassis environment pem.

  • user@host> show chassis environment pem

    For DC-powered routers with two-input 160-A DC power supplies, three-input 240-A DC power supplies or four-input 240-A DC power supplies, the output is similar to the following:

    For two-input 160-A DC power supplies, three-input 240-A DC power supplies in 2–INPUT mode, and four-input 240-A DC power supplies, the current sharing between DC power supplies relies on equal voltages at the input terminals of the power supplies. However, if the voltages do not match, the router operates normally as long as the DC input voltages are within the operating range provided in T640 DC Power System Electrical Specifications .

  • For DC-powered routers with six-input DC power supplies, the output is similar to the following:

    user@host> show chassis environment pem

  • For AC-powered routers, the output is similar to the following:

    user@host> show chassis environment pem