I have a DC-DC converter (50v to 5v) and have it connected to my 50v inverter battery circuit (200a capacity). The device consumes less than 1a. I'd like to use an in-line barrel fuse or other suitable fuse but am struggling to find something low current in the 50v DC range. What should I be using?

 

5x20mm cartridge fuse.
Available down to 100mA
breaking capacity 10kA

 

Check with Digikey (or similar):

https://www.digikey.com/en/products...AgxqYW1rYOTgQuEQBqnkqSvJrqAbx6IlBgovmQ5LxqakA

Lots of options all the way down to 20 mA.

You need to decide things like: What is the max current, what size do you want the fuse, do you want fast-blow or slow-blow.

Remember that you don't need to choose a fuse that is rated at 50 V, just one that is rated at 50 V or more. So using a 250 V rated fuse is perfectly fine.

 

Check with Digikey (or similar):

https://www.digikey.com/en/products/filter/fuses/139?s=N4IgjCBcpgbFoDGUBmBDANgZwKYBoQB7KAbRACYAWADgHZqBmEAqu685kSy2gVgYgBdAgAcALlBABlMQCcAlgDsA5iAC+LAAzVqCEOMkBVRfLEB5FAFkcaLAFdZOTnckBBTgFs0AD0kQNFGCUTND6EpAgxqYW1rYOTgQuEQBqnkqSvJrqAbx6IlBgovmQ5LxqakA

Lots of options all the way down to 20 mA.

You need to decide things like: What is the max current, what size do you want the fuse, do you want fast-blow or slow-blow.

Remember that you don't need to choose a fuse that is rated at 50 V, just one that is rated at 50 V or more. So using a 250 V rated fuse is perfectly fine.

Thanks, just taken a look and it looks like there's only 1 rated at 125v DC. Will that be OK on a 50V system?

 

When you say that there's only one rated at 125 V, what is it that you are narrowing things down with? What current? What size? How fast?

Using a fuse rated for 125 V DC in a circuit that can see, at most, 50 VDC across the fuse when it opens is just fine.

This is akin to needing a string can withstand 50 lb of force and using one that can withstand 125 lb.

 

A good option would be a 1A or 2A fuse, which should provide ample protection without risking damage to your setup. You can check online or visit an electronics store to find suitable options, and don't hesitate to ask for help from a salesperson or expert if you're unsure.