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MX960 AC Power Supply Description

Four types of AC power supplies can be used: normal-capacity, high-capacity, high-capacity second-generation, and high-voltage second-generation universal (HVAC/HVDC) power supplies (for more information on the HVAC/HVDC power supplies, see MX960 High-Voltage Second-Generation Universal (HVAC/HVDC) Power Supply Description. Each of the high-capacity power supplies has a corresponding AC receptacle located in the MX960 chassis directly above the power supply. High-capacity second-generation have two AC receptacles on the power supply itself. Each receptacle requires a dedicated AC power feed and a dedicated breaker. For all power supplies the circuit breaker protection should be designed according to National Electrical Code (NEC) or any similar local standard based on maximum drawn current of the power supply specified in this document. See AC Power Cord Specifications for the MX960 Router for more details.

Normal-capacity AC power supply configurations have one overall zone that provides power to all components in the MX960 chassis. The DC and high-capacity AC, and high-capacity second-generation AC power supply configurations have two zones each of which provide power to specific components in the MX960 chassis.

Figure 1 and Figure 2, Figure 3, and Figure 4 illustrate normal-capacity and high-capacity AC power supplies for the MX960.

Figure 1: MX960 Normal-Capacity AC Power SupplyMX960 Normal-Capacity AC Power Supply
Figure 2: MX960 with High-Capacity AC Power Supplies InstalledMX960 with High-Capacity AC Power Supplies Installed
Note:

The chassis is shown with the extended cable manager.

Figure 3: MX960 High-Capacity Second-Generation AC Power SupplyMX960 High-Capacity Second-Generation AC Power Supply
Figure 4: MX960 with High-Capacity Second-Generation AC Power Supplies InstalledMX960 with High-Capacity Second-Generation AC Power Supplies Installed
  1
Air exhaust
  4
Power supply ejectors
  2
Power distribution unit cover
  5
Grounding points
  3
Power supplies
  6
ESD
Note:

The chassis is shown without the extended cable manager.

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 Model Configuration Minimum Required Number of Power Supplies Model Number

MX960

High-capacity AC

One per zone x two zones = 2 power supplies

PWR-MX960-4100-AC

MX960

Normal-capacity AC

Three power supplies

PWR-MX960-AC

MX960

High-capacity second-generation AC

One per zone x two zones = 2 power supplies

MX960-PSM-5K-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 38 A per feed at 264 VAC.

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 an 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 an AC outlet. Next, plug the second power cord into the AC receptacle on the AC power supply and plug the other end into an 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

High-Capacity Second-Generation AC Power Supplies

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

In the one-feed mode, the power supplies provide power at a reduced capacity (2000 W). In the two-feed mode, the power supplies provide power at full capacity (5100 W). To operate the MX960 at full capacity, you must use the two-feed mode. High-capacity second-generation AC power supplies require one power cord per feed. Therefore, to operate the MX960 at full capacity, you need eight power cords.

Each high-capacity second-generation AC power supply accepts two AC feeds in two C19/C20 AC receptacles, both receptacles are located on the power supply. Do not use the receptacle located on the chassis. For supported power cables, see AC Power Cord Specifications for the MX960 Router.

When using the high-capacity second-generation AC power supplies in one-feed mode, plug one end of the power cord into the corresponding AC receptacle directly on the power supply and the other end into an AC outlet. When using the high-capacity second-generation AC power supply in two-feed mode, you need two power cords. Plug both power cords into the AC receptacles on the power supply the other ends of the cable into AC outlets.

In high-capacity second-generation AC power supply configurations, there are two zones that provide power to specific components in the MX system. Redundancy is 1+1 per zone. Table 2 lists the components that receive power for each zone in a high-capacity AC power supply configuration.

Table 3: Zoning for High-Capacity Second-Generation Power Supplies in an MX960

Chassis Power Configuration

Zone

Power Supply (PEM)

Components Receiving Power

High-capacity second-generation AC power supplies

Zone 0

PEM 0 or 2

  • Lower fan tray

    DPC/MPC slots 6 through 11

  • SCB slots 1 through 2

High-capacity second-generation AC 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 or high-capacity second-generation 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 5.

Figure 5: Setting the Input Mode Switch (DIP Switch)Setting the Input Mode Switch (DIP Switch)
Figure 6: Setting the Input Mode Switch (DIP Switch) on High-Capacity Second-Generation AC PSMSetting the Input Mode Switch (DIP Switch) on High-Capacity Second-Generation AC PSM
  1
Position 1 indicates two AC feeds are present
  2
Position 0 indicates one AC feeds is present

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

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

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.