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Solar fuse for 48v system

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hbl

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Mar 18, 2022
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I have a 48v system and I need to add a few DC-DC converter to get 13.8, 19 and 24 volt output. They are each around 400-700watt output. So on the 48v side they will use around 12-15Amp at max load

I already have 20A circuit breaker, but its a good Idea to also add a fuse, so if the DC-DC converter make a complete short circuit and the breaker dosnt trip, then the fuse hopefully save the rest of the system. Might be overdoing things, but thats not the question.

The question is, can you use solar fuse to protect the system from a short circuit, not from solar panels, but from small unit connected in the same way as a solar panel, except the voltage is not 1000v, but more like 48v. Like this one: NQFU2Z-63. Below is the spec for it and it can be seen here on the manufactors webpage:


and it on sale on Aliexpress: https://www.aliexpress.com/item/1005004226887709.html

1702227072025.png
 
SeaGal said:
Fuses are required to protect the wires, so first check the wire gauges to the buck converters and fuse accordingly. A specialist high-voltage solar fuse is not required for 48V dc - a regular glass / ceramic or midi type fuse would be appropriate, provided it is rated for up to about 60V for a nominal 48V system.

A good guide to DC wiring and fuses can be found here...
Click to expand...
I do get the fuses is to protect the wire, but in order to protect the 2.5mm2 wires on the buck converter (yes they cant be changed) I need a fuse that is sized accordingly to the wire on buck converter 48v volt side. My question is can the above solar fuse at 10Amp be used in this case, its rated for up to 1000v DC and comes in many sized?
 
hbl said:
My question is can the above solar fuse at 10Amp be used in this case, its rated for up to 1000v DC and comes in many sized?
Click to expand...

My question would be why would you want to use a fuse class of gPV that is specifically designed for the characteristics of protecting PV panels, rather than just use a general purpose gG class fuse? The gG category of fuse is more appropriate for your application (protection of 48V to a DC-DC converter) and will likely cost less than a gPV class fuse which may not have the most appropriate characteristics.

Maybe you just have a lot of spare gPV fuses, so are looking to save money?
 
SeaGal said:
My question would be why would you want to use a fuse class of gPV that is specifically designed for the characteristics of protecting PV panels, rather than just use a general purpose gG class fuse? The gG category of fuse is more appropriate for your application (protection of 48V to a DC-DC converter) and will likely cost less than a gPV class fuse which may not have the most appropriate characteristics.

Maybe you just have a lot of spare gPV fuses, so are looking to save money?
Click to expand...
I dont have any gPV fuses, I just wanted to use the DIN RAIL fuse mount instead of an Inline cable fuse. But from what I can see it should be possible to use the DIN RAIL fuse mount and just change the gPV fuse (10x38mm) to a gG fuse at a given Amp-rating that is within the spec. of the DIN RAIL fuse mount, in this case max is 63Amp fuse.

I had to look up the gG fuse and found this doc: https://docs.rs-online.com/59f1/0900766b8002f039.pdf but I cant figure out if its AC or DC voltage rating, as I understand AC Rating cant be used on DC, because of the way an Arc can form compared to AC and that require specific DC fuse to handle this. Im I missing something here ?
 
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