MX2010 DC Power Distribution Description (-48 V)

Most sites distribute DC power through a main conduit that leads to frame-mounting DC power distribution panels, one of which might be located at a location near the rack that houses the router. A pair of cables (one input and one return) connects each set of PDM input terminal studs to the power distribution panel.

The PSMs can be connected to two separate feeds from different sources that are used for feed redundancy. There are two PDMs located in slots PDM0/Input0 and PDM1/Input1 that are capable of carrying seven to nine feeds each. Each feed is connected from one source to one PDM and feeds from the other source to the second PDM of the DC power system. This configuration balances power draw for the system by using the commonly deployed A/B feed redundancy.

Each system provides N+1 PSM redundancy along with N+N feed redundancy. If both DC feeds are available, operating power draws from the feed with higher voltage. These feeds are set by the input mode DIP switch located on the DC PSM (see MX2010 DC Power Supply Module (-48 V) Description). Each set of power cables powers a single DC PSM and is capable of delivering 2500 W of power if 80-A feeds are connected. If feeds that connect to one PDM fail in a redundant configuration, the other feed starts to provide full power.

Figure 1 shows a typical DC source cabling arrangement.

Figure 1: Typical DC Source Cabling to the Router

All DC PSMs in a subsystem share the load. If one PSM fails in a redundant configuration, the remaining PSMs provide power to FRUs. Up to nine PSMs might be required to supply power to a fully configured router. A portion of power from each zone is reserved to power critical FRUs. These FRUs allow the system to operate even if power to a complete zone fails.