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DC Power Supply in EX4300 Switches

The DC power supply in EX4300 switches is a hot-insertable and hot-removable field-replaceable unit (FRU): You can install it without powering off the switch or disrupting the switching function.

All the EX4300 switches that are powered by DC power supplies except EX4300-24T-S, EX4300-24P-S, EX4300-32F-S, EX4300-48T-S, and EX4300-48P-S switches are shipped with one DC power supply pre-installed in the rear panel of the switches. EX4300-24T-S, EX4300-24P-S, EX4300-32F-S, EX4300-48T-S, and EX4300-48P-S switches are not shipped with pre-installed power supplies; you must order them separately.

This topic describes the DC power supplies.

Caution: Do not mix:

  • AC and DC power supplies in the same chassis
  • Power supplies with different airflow labels (AIR IN (AFI) and AIR OUT (AFO)) in the same chassis.
  • Fan modules with different airflow labels (AIR IN (AFI) and AIR OUT (AFO)) in the same chassis.
  • Power supplies and fan modules with different airflow labels (AIR IN (AFI) and AIR OUT (AFO)) in the same chassis.

This topic includes:

Characteristics of a DC Power Supply

EX4300 switches support 550 W DC power supply (see Figure 23). The DC power supplies support Power over Ethernet (PoE+) in EX4300-24P, EX4300-24P-S, EX4300-48P, and EX4300-48P-S models.

Figure 23: DC Power Supply for an EX4300 Switch

DC Power Supply for
an EX4300 Switch

You can install up to two DC power supplies in an EX4300 switch. Power supplies are installed in the power supply slots labeled PSU 0 and PSU 1 in the rear panel of the chassis.

Table 29 lists the details of the 550 W DC power supplies used in EX4300 switches.

Table 29: Details of the DC Power Supplies in EX4300 Switches

Details

550 W DC Power Supply

Model number

  • JPSU-550-DC-AFO-A
  • JPSU-550-DC-AFI-A

Field-replaceable unit (FRU) type

Hot-insertable and hot-removable

Power supply weight

2.43 lb (1.1 kg)

Minimum installed in chassis

1

Maximum installed in chassis

2

Power supply slots

Install in power supply slots labeled PSU 0 and PSU 1 in the rear panel of the chassis.

Fans

Internal

Airflow

  • Front-to-back, indicated by label AIR OUT (AFO)
  • Back-to-front, indicated by label AIR IN (AFI)

Power supply status LEDs

IN OK and OUT OK

DC input current rating

4 A

Operating range

–38 through –60 VDC

Note: The minimum input power required to power on the switch is –43.5 +/– 0.5 VDC. After the switch is powered on, the operating range is –38 through –60 VDC.

To prevent electrical injury while installing or removing DC power supplies, carefully follow instructions in Installing a DC Power Supply in an EX4300 Switch and Removing a DC Power Supply from an EX4300 Switch.

DC Power Supply Airflow

Each power supply has its own fan and is cooled by its own internal cooling system.

Each power supply has a label AIR OUT (AFO) or AIR IN (AFI) on the faceplate of the power supply that indicates the direction of airflow in the power supply.

Table 30 lists the DC power supply models and the direction of airflow in them.

Table 30: Airflow Direction in DC Power Supply Models for EX4300 Switches

Model

Label on Power Supply

Direction of Airflow

JPSU-550-DC-AFO-A

AIR OUT (AFO)

Front-to-back—that is, air intake to cool the chassis is through the vents on the front panel of the chassis and hot air exhausts through the vents on the rear panel of the chassis.

JPSU-550-DC-AFI-A

AIR IN (AFI)

Back-to-front—that is, air intake to cool the chassis is through the vents on the rear panel of the chassis and hot air exhausts through the vents on the front panel of the chassis.

N+0 Redundancy Configuration of DC Power Supplies

In an N+0 redundancy configuration, no power is reserved for resiliency regardless of number of power supplies installed in the switch.

Depending on the power supplies installed in the switch, you can determine the system power budget.

  • If one power supply is installed in the switch:

    System power budget = Output wattage of the installed power supply (PSU(W))

  • If two power supplies are installed in the switch:
    System power budget = (Sum of the output wattage of the two power supplies) – (10% of the output wattage of the installed power supply)

    System power budget = PSU0(W) + PSU1(W) – (0.10 x (PSU(W))

Table 31 lists the N+0 power calculation for EX4300 switches that use 550 W DC power supplies.

Table 31: N+0 DC Power Calculations for EX4300 Switch Configurations

Switch Configuration

Number of Power Supplies

Total Power (in watts)

System Power Budget (in watts)

Backup Power (in watts)

Base Power (in watts)

Available PoE Power (in watts)

Ports Enabled for PoE+

24-port EX4300 switch

1

550

550

0

150

400

13

2

1100

1045

0

150

895

24

32-port EX4300 switch

1

550

550

0

149

N/A

N/A

2

1100

550

550

160

N/A

N/A

48-port EX4300 switch

1

550

550

0

175

375

12

2

1100

1045

0

175

870

29

N+N Redundancy Configuration of DC Power Supplies

You can configure your switch for N+N redundancy, in which N power supplies can be removed or fail and the remaining N power supplies continue to supply power for the switch without interruption.

You can configure the power management software to manage switch power for N+N redundancy. When you configure power management for N+N redundancy, half of the total power available (N) is held as reserve power while the other half (N) is available for immediate consumption. If the switch configuration changes and requires additional power, then additional power is drawn from the reserve power, and the switch no longer has N+N power supply redundancy. This condition raises a minor alarm. If the condition is not corrected within 5 minutes, then a major alarm is issued.

For more information about how power management allocates power to chassis components when power is insufficient, see Understanding Power Management on EX Series Switches.

Depending on the power supplies installed in the switch, you can determine the system power budget.

  • If one power supply is installed in the switch:
    • System power budget = Output wattage of the installed power supply (PSU(W))
    • Backup power available = 0 W

    A minor alarm is raised as switch has no N+N power supply redundancy.

  • If two power supplies are installed in the switch:
    • System power budget = (Output wattage of one power supply) – (5% of the output wattage of one power supply)

      System power budget = PSU(W) – (0.05 x PSU(W))

    • Backup power available = (Output wattage of one power supply) – (5% of the output wattage of one power supply)

      System power budget = PSU(W) – (0.05 x PSU(W))

Table 32 lists the N+N power calculation for EX4300 switches that use 550 W DC power supplies.

Table 32: N+N DC Power Calculations for EX4300 Switch Configurations

Switch Configuration

Number of Power Supplies

Total Power (in watts)

System Power Budget (in watts)

Backup Power (in watts)

Base Power (in watts)

Available PoE Power (in watts)

Ports Enabled for PoE+

24-port EX4300 switch

1

550

550

0

150

400

13

2

1100

522.5

522.5

150

372.5

12

32-port EX4300 switch

1

550

550

0

149

N/A

N/A

2

1100

550

550

160

N/A

N/A

48-port EX4300 switch

1

550

550

0

175

375

12

2

1100

522.5

522.5

175

347.5

11

Related Documentation

Modified: 2015-06-23