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Calculating DC Power Requirements for MX2010 Routers

 

The information in this topic helps you determine which PSMs are suitable for various configurations, as well as which PSMs are not suitable because output power is exceeded. You determine suitability by subtracting the total power draw from the maximum output of the PSMs. Afterward, you calculate the required input current. Finally, you calculate the thermal output. A sample configuration is provided in Table 1.

We recommend that you provision power according to the maximum input current listed in the power system electrical specifications (see MX2010 DC Power (-48 V) System Electrical Specifications ).

Use the following procedures to calculate the power requirement:

  1. Calculate the power requirement.
  2. Evaluate the power budget.
  3. Calculate input power.
  4. Calculate thermal output (BTUs) for cooling requirements.

The MX2010 DC power system provides power to the FRUs in the chassis (see Table 1 for information about power). Each power system is made up of two DC PDMs, nine PSMs, ten MPCs, four fan trays, eight SFBs, and two Control Board and Routing Engines (CB-REs).

When calculating power requirements, be sure that there is adequate power for the system.

Table 1: MX2010 DC Power System Sample Configuration

Chassis Power Configuration

Power Distribution Modules (PDMs)

Power Supply Modules (PSMs)

Description

3 PSMs, 2 CB-REs, 8 SFBs, and 4 fan trays (no line cards installed)

PDM 0 and 1

3 PSMs

The power consumed by CB-REs and SFBs is 250 W each.

The power consumed by 2 CB-REs and 8 SFBs is 2.5 KW.

The power consumed by fan trays 0 and 1 is 2 KW and fan trays 2 and 3 is 1 KW.

The total Kilowatts of power consumed is 5.5 KW.

10 Line cards

PDM 0 and 1

5 PSMs

Each line card consumes up to 1 KW. One PSM is needed for every set of 2 line cards.

N+1 redundant system with N+N redundancy for SFBs, CB-REs, and 1 out of 2 fan trays.

PDM 0 and 1

9 PSMs

This provides N+N redundnacy for critical FRUs (CB-REs, SFBs, and fan trays) and N+1 redundancy for line cards.

  1. Calculate the power requirements (usage) using the values in MX2010 DC Power Requirements as shown in Table 2.

    Table 2: Typical DC Power Requirements for MX2010 Router

    Component

    Model Number

    Power Requirement (Watts) with 91% Efficiency

    Base chassis

    CHAS-BP-MX2010-BB

    Fan trays (upper and lower)

    MX2000-FANTRAY-BB

    1700 * 2 + 500* 2 W = 4400 W

    MPC

    MPC-3D-16XGE-SFPP

    440 W * 10 = 4400 W

    ADC

    ADC

    150 W * 10 = 1500 W

    CB-RE

    RE-MX2000-1800X4-S

    250 W * 2 = 500 W

    SFB—slots 0 through 7

    MX2000-SFB-S

    220 W * 8 = 1760 W

    MX2010 DC power system ( 60 A feeds to each PDM input)

    MX2010 DC power system ( 80 A feeds to each PDM input)

    2100 W * 8 PSMs=16,800 W (+ 1 PSM@2100 W redundant capacity)

    2500 W * 8 PSMs=20,000 W (+ 1 PSM@2500 W redundant capacity)

  2. Evaluate the power budget, including the budget for each configuration if applicable, and check the required power against the maximum output power of available PDM options.

    Table 3 lists the PSMs, their maximum output power, and unused power (or a power deficit).

    Table 3: Calculating DC Power Budget

    Power Supply Module

    Maximum Output Power of Power Supply Module (Watt)

    Maximum Output Power for System (Watt)—Including Redundant Capacity

    MX2010 DC PSM 60 A (feed to each input)

    2100

    18,900

    MX2010 DC PSM 80 A or DC PSM (240 V China) (feed to each input)

    2500

    22,500

  3. Calculate input power. Divide the total output requirement by the efficiency of the PSM as shown in Table 4.

    Table 4: Calculating DC Input Power

    Power Supply Module

    Power Supply Module Efficiency

    Output Power Requirement (Watt)—per PSM

    Input Power Requirement (Watt)—per PSM

    MX2010 DC PSM 60 A

    91%

    2100

    2307

    MX2010 DC PSM 80 A or DC PSM (240 V China)

    91%

    2500

    2747

  4. Calculate thermal output (BTUs). Multiply the input power requirement (in watts) by 3.41 as shown in Table 5.

    Table 5: Calculating DC Thermal Output

    Power Distribution Module

    Thermal Output (BTUs per hour)

    MX2010 DC PDM

    34.5 KW divided by 0.91 * 3.41 = 129,280 BTU/hr.

    34.5 KW of output power consumed by the chassis. This is the maximum output the chassis can consume in a redundant configuration. The input power is 16.5 divided by 0.91 = 37.9 KW.