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islander avatar image
islander asked

Lynx Distributor 24V fuse sizing?

Hi! I'm about to purchase a Lynx Distributor, but the Mega fuse sizing is giving me trouble. I've already checked these sources ...

- https://www.victronenergy.com/upload/documents/Wiring-Unlimited-EN.pdf

- https://community.victronenergy.com/questions/56077/lynx-distributor-usages-clarifications.html

... but I want people to check my math. The system has a 24V flooded lead acid battery. After I've found out current, do I choose a 32V fuse for the same current?


Lynx Distributor:

Slot 1/ Multiplus II 24V 3000VA

- Maximum load is 5500W / 24V = 229A

- Mega fuse 225-250A/32V ?


Slot 2/ Solar charge controller

- Maximum inflow is 1440W / 24V = 60A

- Mega fuse 60-70A/32V?

Slot 3/ Wind charge controller

- Maximum inflow is 800W (actually less than 30W...) / 24V = 33A

- Mega fuse 35A/32V ?

Slot 4/ Victron non-isolated DC-DC converter 24V->12V

- Maximum load is 200W / 24V = 8A

- Mega fuse 8-10A/32V ?


Also, in the left side of the distributor I will be connecting the battery bank with external fuse and SmartShunt. I also need to power the Cerbo GX. The manual says it is preferred to be powered by the bus bar instead of a conveter. Can I connect it to the left side also with the battery, because it has it's own slow blow 3.1A fuse?

The final problem is that 60A/32V are smallest Mega fuses widely available. I've seen a few 50A/32V. Is there anything smaller for my case for slot 4? Thanks!

fuses
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1 Answer
seb71 avatar image
seb71 answered ·

You select the fuse rating to protect the wire (the fuse must blow at a current which the wire can still safely carry).

And you select the wire cross section to be able to safely carry the required current.


If the smallest fuse you can find in a certain format is 32A, you can use that 32A fuse for a 8A load as long as the wire can safely withstand a current greater than 32A.


The voltage the fuse is rated for must be higher than the highest voltage you will have on that wire. Otherwise, even if the fuse blows due to a shortcircuit for instance, it might not be able to extinguish the electric arc and you will still have a closed circuit.


-------

All negative wires from loads and chargers, including the one powering the Cerbo GX must be on the "Load Minus" side of the SmartShunt.

Edit:
Deleted last part. I was thinking of the SmartShunt positive wire.

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