Decapede and fuse ratings
Posted by bobc
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Decapede and fuse ratings January 26, 2014 10:20AM |
Registered: 14 years ago Posts: 1,236 |
I am working on a revision of the Decapede board [reprap.org].
The Decapede is spec'ed for 24A total continuous at 24V. I think that is doable with 2oz copper and generous traces (rule of thumb, 100 mil is good for 10A).
The board has a single fuse, rated up to 60A. I think that is a bit optimistic, but even with a smaller fuse it means that up to 24A could be dumped into any output (hotend heater, stepper driver) before the main fuse blows. I would think that there is a lot of melting that could take place before the main fuse provides protection.
So I am thinking some smaller fuses wold be a good idea to limit current, either singly in groups. As usual, space and cost are issues. I see there are surface mount fuses which are small but not very cheap. Dare I say, PTCs?
Can suggest anything that is small, cheap and effective, or maybe should I try something else/not bother?
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The Decapede is spec'ed for 24A total continuous at 24V. I think that is doable with 2oz copper and generous traces (rule of thumb, 100 mil is good for 10A).
The board has a single fuse, rated up to 60A. I think that is a bit optimistic, but even with a smaller fuse it means that up to 24A could be dumped into any output (hotend heater, stepper driver) before the main fuse blows. I would think that there is a lot of melting that could take place before the main fuse provides protection.
So I am thinking some smaller fuses wold be a good idea to limit current, either singly in groups. As usual, space and cost are issues. I see there are surface mount fuses which are small but not very cheap. Dare I say, PTCs?
Can suggest anything that is small, cheap and effective, or maybe should I try something else/not bother?
What is Open Source?
What is Open Source Hardware?
Open Source in a nutshell: the Four Freedoms
CC BY-NC is not an Open Source license
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Re: Decapede and fuse ratings January 26, 2014 10:50AM |
Registered: 12 years ago Posts: 466 |
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Re: Decapede and fuse ratings January 27, 2014 05:24PM |
Registered: 14 years ago Posts: 1,236 |
Yep, the mini auto fuses seem like a decent compromise. They are cheap and relatively compact.
There are fuses and PTCs in surface mount 1206 sizes, the fuses are one shot, so maybe not so useful. There are some "nano" fuse holders in small size, little more expensive though. The nano fuses would be awkward for the user to replace.
So I think mini auto fuses to protect the outputs with 20A for the heat bed output, 20A combined for the heaters and 20A for the stepper drivers. I might also put in 1206 PTCs for individual outputs, they could trip around 4A and hold at 40A, so hopefully should cause the 20A fuse to blow.
Adding fuses now will need a bit of rework, so I might play with the layout later.
If interested is interested in reviewing some schematics, all the files are here [github.com]
Comments welcome!
What is Open Source?
What is Open Source Hardware?
Open Source in a nutshell: the Four Freedoms
CC BY-NC is not an Open Source license
There are fuses and PTCs in surface mount 1206 sizes, the fuses are one shot, so maybe not so useful. There are some "nano" fuse holders in small size, little more expensive though. The nano fuses would be awkward for the user to replace.
So I think mini auto fuses to protect the outputs with 20A for the heat bed output, 20A combined for the heaters and 20A for the stepper drivers. I might also put in 1206 PTCs for individual outputs, they could trip around 4A and hold at 40A, so hopefully should cause the 20A fuse to blow.
Adding fuses now will need a bit of rework, so I might play with the layout later.
If interested is interested in reviewing some schematics, all the files are here [github.com]
Comments welcome!
What is Open Source?
What is Open Source Hardware?
Open Source in a nutshell: the Four Freedoms
CC BY-NC is not an Open Source license
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