DC Bus

For systems with multiple power flows a DC Bus is essential. They provide a structure to connect each branching power line, sometimes including options for branch fusing and monitoring.

A readily accessible DC Bus is also invaluable for testing and maintenance as it allows each separate element of the system to be checked and in some cases isolated individually.

• For a small, simple system you probably don’t!
• A DC Bus should be included when you have multiple cables connecting to a terminal or other termination point. Up to 2 lugs are usually easy to accommodate on a single post bolt, but once you have 3 or more it becomes impractical both for cable control as well as for ensuring secure low-resistance connections. Too many wires ‘ganged up’ on a terminal also makes maintenance and troubleshooting very difficult.

• For a small, simple system you probably don’t!
• But if the system has multiple devices connecting on both the upstream and downstream sides (i.e. multiple charging devices and multiple discharging devices) it is often sensible to use multiple DC Buses to consolidate the separate sides.
• This is even more when using a shunt to monitor battery SOC. Both charging and discharging devices are ‘loads’ as far as the shunt is concerned, so they will connect to the ‘load’ terminal. For a system with a single charge and a single discharge connection, the ‘load’ terminal can be the common point of connection. But as above, any more than 2 connections becomes impractical, so a Bus should be used on any ‘crowded’ section of a DC system.

• System currents can rise very quickly in DC systems, especially at lower voltages. Ensure your DC Bus has sufficient current rating to handle the maximum worstcase current load of all the connected devices – even if that usage case is not supposed to ever happen!

• Consider what size lugs you will use on your cables and what size your Bus will accommodate.
• Consider cable paths and cable entry needs, including any limits on cable gauge/OD for any Bud Covers.
• Consider how many wires/devices you will be connecting to the Bus and ensure that the Bus has sufficient connection points for all the devices (and maybe a few spares – just in case……).

• No: simple Bus models require device fusing be installed separately.
• Partially: some Bus models incorporate mounting bays for fixed POSITIVE fuses.