Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?

 

Maintaining the T1600 Power Supplies

 

Purpose

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

Action

On a regular basis:

  • 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 accumulating near the router. To review grounding and site wiring requirements for the router, see T1600 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 air filter element, see the following topics:

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

    During normal operation:

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

    • For DC power supplies, each green INPUT PRESENT LED on a DC power supply lights when the input is receiving source DC power.

    • For three-input 240 -A power supplies and four-input 240 -A DC power supplies, each CB ON LED on a DC power supply lights when the circuit breaker is on.

  • Routinely check the LEDs on the AC power supply faceplates. If the AC OK LEDs are lit, the AC terminal blocks are receiving power. If the DC OK LEDs are lit, the AC power supplies are 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 following CLI command:

    user@host> show chassis alarms
  • Issue the show chassis environment pem command to check the status of the power supplies.

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

      user@host> show chassis environment pem

      If 0 is displayed for the SCG/CB/SIB in the Current, Power, and Load fields for a PEM, and the voltage field does not match the other PEM, it might indicate a difference between the DC input voltages applied to PEM0 and PEM1. Consider checking your DC power network for unintended voltage drops to the router (see Typical DC Source Cabling to the Router for a typical DC source cabling arrangement).

      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 Power System Electrical Specifications.

      • For the three-input 240-A DC power supplies, system power is divided into two load zones. One load zone consists of INPUT 0 of PEM0 and PEM1. The other load zones consist of INPUT 1 and INPUT 2 of PEM0 and PEM1. Load sharing occurs between the two power supplies for each load zone. Therefore, the input voltage for the inputs in each load zone must be equal in both power supplies for current sharing. For example, the input voltage for INPUT 0 of PEM0 and the input voltage for INPUT 0 of PEM1 must be the same for current sharing to occur within that load zone.

      • For the four-input 240-A DC power supplies, system power is divided into four load zones. One load zone consists of INPUT 0 of PEM0 and PEM1. The other load zones consist of INPUT 1, INPUT 2 and INPUT 3 of PEM0 and PEM1. Load sharing occurs between the two power supplies for each load zone. Therefore, the input voltage for the inputs in each load zone must be equal in both power supplies for current sharing. For example, the input voltage for INPUT 0 of PEM0 and the input voltage for INPUT 0 of PEM1 must be the same for current sharing to occur within that load zone.

    • 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

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