Technical Documentation

Power Consumption for a DC-Powered SRX5800 Services Gateway

We recommend that you provision at least 116 A  (58 A per feed) @ –48 VDC (nominal) for the system.

If you do not plan to provision at least 116 A  (58 A per feed) @ –48 VDC (nominal) for the system, you can use the information in Table 1 and Table 2 to calculate the power consumption @ –48 VDC and thermal output for your hardware configuration.

Table 1 lists the power requirements for base DC-powered services gateways operating under typical voltage conditions and includes nonredundant and redundant power supply configurations.

Note: The base DC-powered services gateway includes the midplane, craft interface, and fan trays running at normal speed.

Table 1: DC Base Services Gateway Power Requirements

DC Power Supply Configuration

Power Requirement (Watts)

Current Requirement (Amps @ –48 VDC)

Nonredundant DC configuration includes two DC power supplies, the midplane, craft interface, and fan trays running at normal speed.

400 W (approximate)

8.3 A (approximate)

Redundant DC configuration includes four DC power supplies, the midplane, craft interface, and fan trays running at normal speed.

400 W (approximate)

8.3 A (approximate)

Table 2: Component DC Power Requirements

Component

Power Requirement (Watts)

Current Requirement (Amps @ –48 VDC)

SCB

150 W

3.1 A

Routing Engine

90 W

1.9 A

Cooling system (full speed – normal speed)

600 W – 400 W = 200 W

4.2 A

IOC—Generalized typical value

312 W

6.5 A

IOC—Generalized maximum value

365 W

7.6 A

SPC—Generalized typical value

213 W

4.4 A

SPC—Generalized maximum value

351 W

7.3 A

These examples use generalized values for DPCs.

Typical power consumption for DC-powered devices:

  • Power consumption for minimum configuration:
    Base device and two power supplies + 2 SCBs + 1 Routing Engine + 1 IOC + 1 SPC—Generalized typical value =
    8.3 A +2( 3.1) A + 1.9 A + 6.5 A + 4.4  A = 27.3 A @ –48 VDC = 1310 W
  • Power consumption for maximum configuration:
    Base device and four power supplies + fan tray at full speed + 2 SCBs + 1 Routing Engine + 10 IOCs + 1 SPC—Generalized maximum value =
    8.3 A + 4.2 A + 2(3.1 A) + 1.9 A + 10(7.6 A) + 7.3 A = 8.3 A + 4.2 A + 6.2 A + 1.9 A + 76 A + 7.3 A = 103.9 A @ –48 VDC = 4987 W
  • Current requirement adjustment for fans running at full speed (high temperature environment or cooling component failure):
    Calculated system current (X) – Cooling (normal) + Cooling (full speed) =
    X A – 8.3 A + 12.5 A =
    X A + 4.2  A
  • Input current from a DC source other than –48 VDC (based on maximum configuration; applies to DC power supply only):
    (–54 VDC input) * (input current X) = (–48 VDC input) * (input current Y)
    54 * X = 48 * 103.9 A
    X = 48 * 103.9 A/54 = 92.4 A
  • System thermal output for maximally configured DC-powered services gateway:
    Watts DC * 3.41 = BTU/hr
    4987 * 3.41= 17,006 BTU/hr

Published: 2009-11-03