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MX960 AC Power Supply Description

 

The MX960 requires special power supplies that are not interchangeable with the MX240, MX480, or the MX2000 series routers. Two types of AC power supplies can be used: normal-capacity or high-capacity. Each AC power supply has a corresponding AC appliance inlet located in the MX960 chassis directly above the power supply. Additionally, high-capacity AC power supplies have an AC appliance inlet on the power supply itself. Each inlet requires a dedicated AC power feed and a dedicated 15 A (250 VAC) circuit breaker for the normal-capacity power supply and 38 A (264 VAC) circuit breaker for the high-capacity power supply. One power cord per feed is required. See AC Power Cord Specifications for the MX960 Router for more details.

Normal-capacity and high-capacity AC power supply configurations are zoned meaning that certain components in the MX960 chassis are powered by specific power supplies. Normal-capacity AC power supply configurations have one overall zone that provides power to all components in the MX960 chassis. High-capacity AC power supply configurations have two zones that provide power to specific components in the MX960 chassis.

Figure 1 and Figure 2 illustrate normal-capacity and high-capacity AC power supplies for the MX960.

Figure 1: MX960 Normal-Capacity AC Power Supply
MX960 Normal-Capacity
AC Power Supply
Figure 2: MX960 with High-Capacity AC Power Supplies Installed
MX960 with High-Capacity
AC Power Supplies Installed

The minimum number of power supplies must be present in the router at all times. Refer to Table 1.

Table 1: Minimum Number of Power Supplies Required for the MX960

Router ModelConfigurationMinimum Required Number of Power SuppliesModel Number

MX960

High-capacity AC

One per zone x two zones = 2 power supplies

PWR-MX960-4100-AC

MX960

Normal-capacity AC

2

PWR-MX960-AC

Normal-Capacity AC Power Supplies

The MX960 can be powered by three normal-capacity AC power supplies (non-redundant configuration) or four normal-capacity AC power supplies (redundant configuration). In a non-redundant configuration, the three AC power supplies share power almost equally within a fully-populated MX960 system. In a redundant configuration there is full power redundancy meaning if one power supply fails or is removed, the remaining power supplies instantly assume the entire electrical load without interruption and provide full power for the maximum configuration for as long as the router is operational.

Note

Each normal-capacity power supply must be connected to a dedicated AC power feed and a dedicated customer site circuit breaker. Juniper recommends that you use a 15 A (250 VAC) minimum, or as required by local code.

High-Capacity AC Power Supplies

The MX960 can also be powered by two high-capacity AC power supplies. The high-capacity power supplies must be installed in adjacent slots in the chassis. They can operate in one-feed mode or two-feed mode. The maximum inrush current for a high-capacity AC power supply is 38A per feed at 264VAC.

In one-feed mode, the power supplies output power at a reduced capacity (1700W). In two-feed mode, the power supplies provide power at full capacity (4100W). To operate the MX960 at full capacity, you must use two-feed mode. High-capacity power supplies require one power cord per feed. Therefore, to operate the MX960 at full capacity, you will need four power cords.

Each high-capacity AC power supply accepts two AC feeds in two unique AC receptacles, one receptacle located on the chassis and the other on the power supply.

When using the high-capacity AC power supplies in one-feed mode, plug one end of the power cord into the corresponding AC receptacle directly above the power supply in the chassis and the other end into a AC outlet. When using the high-capacity power supply in two-feed mode, you need two power cords. Plug one power cord into the AC receptacle on the chassis and then plug the other end into a AC outlet. Next, plug the second power cord into the AC receptacle on the AC power supply and plug the other end into a AC outlet.

In high-capacity AC power supply configurations, there are two zones that provide power to specific components in the MX system. No current sharing between power supplies is needed with the high-capacity system because the redundancy changes from 3+1 per system to 1+1 per zone.Table 2 lists the components that receive power for each zone in a high-capacity AC power supply configuration.

Table 2: Zoning for High-Capacity Power Supplies in an MX960

Chassis Power Configuration

Zone

Power Supply (PEM)

Components Receiving Power

MX960 AC high-capacity power supplies

Zone 0

PEM 0 or 2

  • Lower fan tray

  • DPC/MPC slots 6 through 11

  • SCB slots 1 through 2

MX960 AC high-capacity power supplies

Zone 1

PEM 1 or 3

  • Upper fan tray

  • DPC/MPC slots 0 through 5

  • SCB slot 0

Understanding Input Mode Switch (DIP Switch) Settings

Each PSM has two input mode switches (DIP switches) on the faceplate. The DIP switches provide critical information to the power management subsystem to help generate alarms in case of a feed failure or a wrong connection. Each PSM has an LED per feed indicating whether the feed is active and whether the feed is properly connected. You must set the DIP switch on each high-capacity AC power supply according to how many feeds are connected. When one feed is connected, the system is running in reduced capacity mode. When two feeds are connected the system is running in full-capacity mode. Use these DIP switch settings:

  • Position-0 indicates one AC feed is present

  • Position-1 indicates two AC feeds are present

Refer to Figure 3.

Figure 3: Setting the Input Mode Switch (DIP Switch)
Setting the Input Mode Switch
(DIP Switch)

Use the show chassis power command to verify that the DIP switch settings on the high-capacity AC power supplies are set to the correct position. Here are examples of the command output:

Example 1: Proper setting of the DIP switch

user@host>show chassis power

In Example 1, PEM 0 is running at full capacity (4100 W) with two AC feeds expected and two AC feeds connected. This indicates that the DIP switch is properly set to Position 1 since two AC feeds are connected. The example also shows that PEM 1 is running at reduced capacity (1700W) with one AC feed expected and one AC feed connected. This indicates that the DIP switch is correctly set to Position 0 since one feed is present.

Example 2 shows the show chassis power command output when the DIP switch is set improperly:

Example 2: Improper Setting of the DIP Switch

user@host>show chassis power

The PEM 0 status indicates the system is Online, the AC Input is OK, is running at full capacity (4100 W) with two AC feeds expected and two AC feeds connected. But notice the status for PEM 1. The State is Present and the AC input is Check (2 feed expected, 1 feed connected). This indicates there is a mismatch between the DIP switch setting and the number of feeds connected. Therefore, the power supply is running at reduced capacity (1700 W). If PEM 1 should be running at full-capacity, verify that there are two feeds connected to the power supplies and the DIP switch is set to position 1.