Juniper Networks MX240 manual DC Power Circuit Breaker Specifications

Appendix D: Power Guidelines, Requirements, and Specifications

1.38A + 0.4 A + 3.1 A + 1.9 A + 3(7.6 A) =

1.38A + 0.4 A + 3.1 A + 1.9 A + 22.8 A =

29.58A @ –48 VDC = 1,420 W DC

■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 * 29.58 A

X = 48 * 29.58 A/54 = 26.3 A

■System thermal output (based on maximally configured DC-powered router):

Watts DC * 3.41 = BTU/hr

1,420 * 3.41 = 4,842 BTU/hr

DC Power Circuit Breaker Specifications

Each DC power supply has a single DC input (–48 VDC and return) that requires a dedicated circuit breaker. We recommend that you use a dedicated facility circuit breaker rated for 40 A (–48 VDC) minimum, or as permitted by local code. Doing so enables you to operate the router in any configuration without upgrading the power infrastructure.

If you plan to operate a DC-powered router at less than the maximum configuration and do not provision a 40 A (–48 VDC) circuit breaker, we recommend that you provision a dedicated facility circuit breaker for each DC power supply rated for at least 125% of the continuous current that the system draws at –48 VDC.

DC Power Specifications and Requirements ■ 169