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Which fuses can be used for protection in the DC area for two directions
#1
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Which fuses can be used for protection in the DC area for two directions

We are having a little discussion right now.
Which safeguards should best be used for protection. I am currently using Schneider 64A and 32A DC fuses for the PCM60 and the solar strings. And for the 5048 PIP and as backup fuse for the batteries, the TOMZN DC TOB1Z-125 C125 (2P 125A DC 600V).

Now "ajw22" had drawn my attention to the fact that there were apparently fire-dangerous problems when using the DC fuses in two directions.

You can find information about the superstructures and the safety devices and also about the discussion here

https://secondlifestorage.com/showthread...265&page=5

What experiences have you had with securing the batteries and systems.
Or what solutions do you have in use with you.

Huh

** Please reply here in the thread. **
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#2
Interesting topic - never gave it a thought before this post.   I use Midnite Solar circuit breakers (15, 30, 80, and 250a) for my off-grid solar system + an ABB SACE S5 as main battery shunt-trip.     Here's an interesting discussion about Midnite Solar circuit breakers that there is indeed a recommended DC 'direction'.....

https://forum.solar-electric.com/discuss...ontroller.

However, it sounds like things will work in the reverse direction? but maybe not as well?
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#3
It sounds like you are referring to a breaker, not a fuse. They are two very different things and one is not a replacement for the other. Where a breaker would fail, a fuse would not.

There are DC and AC breakers, make sure you are looking at a DC breaker.

Tomzn are directional / polarized breakers. Many bi-directional breakers to choose from and in UL 1077 and UL 489, along with the various trip curves for your type of load.

Here is an application guide to bring you up to speed.
https://www.eaton.com/content/dam/eaton/...01009e.pdf
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#4
It's not about breakers.
It's about fuse.

And that there are apparently problems with DC fuses when used in two directions as we always have with island systems and batteries.

I have a breaker as a glow fuse with 160A. Or just use ABB SACE S3, S4 or S5 ... as a breaker.

No We seem to have problems with DC fuses that are of interest to everyone because it represents a fire-dangerous safety risk.
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#5
(06-06-2020, 06:57 AM)Walde Wrote: It's not about breakers.
It's about fuse.

And that there are apparently problems with DC fuses when used in two directions as we always have with island systems and batteries.
The thread you linked is about polarized breakers & in that thread ajw22 actually says fuses are NOT polarized.
I have never heard of directional fuses. I have heard of directional DC breakers.
HRC, automotive & marine fuses are definitely NOT polarized.

Did you have a link to a manufacturer with a polarized fuse product? Or some other links?
Running off solar, DIY & electronics fan :-)
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#6
(06-05-2020, 03:15 PM)Walde Wrote: Now "ajw22" had drawn my attention to the fact that there were apparently fire-dangerous problems when using the DC fuses in two directions.

The issue I mentioned is with DC breakers with polarity, not fuses.  I don't know if there even are directional fuses.
Modular PowerShelf using 3D printed packs.  60kWh and growing.
https://secondlifestorage.com/showthread.php?tid=6458
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#7
(06-06-2020, 09:15 AM)ajw22 Wrote:
(06-05-2020, 03:15 PM)Walde Wrote: Now "ajw22" had drawn my attention to the fact that there were apparently fire-dangerous problems when using the DC fuses in two directions.

The issue I mentioned is with DC breakers with polarity, not fuses.  I don't know if there even are directional fuses.


There are no polarity with fuses that I've seen but there's AC and DC fuses. All has to do with the way it's designed to make it not arc at high voltages.
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#8
Now it's getting exciting.

But let's get to the point.

Are they DC breakers or DC fuses?

Schneider C65H-DC C32A (2P 32A DC 250V)
Schneider C65H-DC C63A (2P 63A DC 250V)
TOMZN DC TOB1Z-125 C125A (2P 125A DC 600V)

According to the imprint, they have a characteristic curve "C" and so I understand it should be fuses.
Please correct me if I am wrong. Am open to learn.


"ajw22" showed me videos that make me a little scared and also thoughtful.


(06-02-2020, 10:44 PM)ajw22 Wrote: Just a FYI:
Those TOMZN DC breakers have a polarity ( ie. flow direction of electrons matters ), thus are theoretically not suitable for use on batteries that can get charged or discharged (thus the direction of current flow can switch).  It's probably ok in this case, considering you're operating at less than 1/10 the rated voltage.  In the worst case, the breaker on tripping will not be able to kill the electric arc inside, and start to catastrophically burn/melt.  A little demonstration:
https://www.youtube.com/watch?v=Oaq2cvoPBRk&t=186s



(06-05-2020, 01:11 PM)ajw22 Wrote: Here's another video showing the dangers of wiring a polarized DC breaker the wrong way.
https://www.youtube.com/watch?v=Cup5fMGaE2g

Now, personally, I assume that a polarized DC breaker rated for 600V will work correctly bi-directionally when running at less than 60V.  But nobody will guarantee that.
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#9
(06-06-2020, 11:27 AM)Walde Wrote: Are they DC breakers or DC fuses?

Schneider C65H-DC C32A (2P 32A DC 250V)
Schneider C65H-DC C63A (2P 63A DC 250V)
TOMZN DC TOB1Z-125 C125A (2P 125A DC 600V)

According to the imprint, they have a characteristic curve "C" and so I understand it should be fuses.
Please correct me if I am wrong. Am open to learn.

All of those are breakers.
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Running off solar, DIY & electronics fan :-)
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#10
(06-05-2020, 03:15 PM)Walde Wrote: Which fuses can be used for protection in the DC area for two directions
I do use a 100a Renogy ANL fuse on one of my 48v batteries.  They also make 20, 30, 40, and 60a...  specs:  https://www.renogy.com/20a-30a-40a-60a-1...et-w-fuse/

* Found a couple of posts that say the 'direction' doesn't matter.
* My Renogy ANL does not have an arrow or anything showing a specific direction - and don't see anything in the specs. 
* The examples all show the fuse on the positive wire rather than negative side.

One cool thing about an ANL... is that it can be turned around (in the holder) - so if you find out at some point that it needs to be reversed you won't have to change any wiring.


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