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.

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.