fuses in series to increase rated voltage?

Kataeb · Nov 6, 2015

can we install 2 or 3 fuses in series to increase rated voltage?
it is for a solar project requiring 800 vdc.
the normally used solar fuses rated 1000 vdc are too expensive, and the project is way above budget.
so we are considering using low cost 400 vac gG fuses, to be put in series, till reaching the required rated voltage.

rdrast · Nov 6, 2015

NO.
Absolutely not.
If one clears, it now has the full over-rated voltage across it, which could cause serious mechanical failure (read: Explosion).

The very last place to cut costs is on safety. If one of my vendors even considered cutting corners on safety systems, they would be immediately blacklisted.

tragically1969 · Nov 6, 2015

rdrast said:
NO.
Absolutely not.
If one clears, it now has the full over-rated voltage across it, which could cause serious mechanical failure (read: Explosion).

The very last place to cut costs is on safety. If one of my vendors even considered cutting corners on safety systems, they would be immediately blacklisted.

I was puzzled as to how the OP thought this would work, surely a 400V fuse is a 400V fuse whatever you do with it ?

Kataeb · Nov 6, 2015

we were just comparing it to the below solution adopted by ABB for their contactors.
do you think that there will be any problems in the below case?

http://www.abb.com/product/seitp329...d=ABB1SFL497025R7211&cid=9AAC100109#downloads
3-pole Contactor suitable for DC-1 applications where all three poles must be connected in series in a 1-pole configuration up to max 1000 VDC

tragically1969 · Nov 6, 2015

Kataeb said:
we were just comparing it to the below solution adopted by ABB for their contactors.
do you think that there will be any problems in the below case?

http://www.abb.com/product/seitp329...d=ABB1SFL497025R7211&cid=9AAC100109#downloads
3-pole Contactor suitable for DC-1 applications where all three poles must be connected in series in a 1-pole configuration up to max 1000 VDC

But that's a contactor and its rated at 1000V ? What relevance has that to a fuse ?

Kataeb · Nov 6, 2015

it is mentioned " Maximum Operating Voltage UL/CSA: Main Circuit 600 V " , so if one pole contact fails...

tragically1969 · Nov 6, 2015

Kataeb said:
it is mentioned " Maximum Operating Voltage UL/CSA: Main Circuit 600 V " , so if one pole contact fails...

You are not comparing like for like, you can't apply contactor ratings to fusing. A fuse is a protective device, a contactor is a switching device. Just fuse it correctly.

jraef · Nov 6, 2015

The added voltage rating from putting contacts in series only applies to switching DC, because it increases the total dielectric in the circuit and quenches the arc before if burns the contact material. That has no bearing on how a fuse works.

JohnCalderwood · Nov 6, 2015

I had to do a double-take on the original question.

No, emphatically NO.

These are fuses, not resistors, nor contactors.
They have a rated voltage and current-carrying capacity.
They are not to be under-specified unless you want a fire/explosion/loss of life.

Please spend the project money on the correct fuses.

BITS N BYTES · Nov 6, 2015

Go ahead and give it a try, might or might not work!!
As YOU will be the first and last person to do this please post pictures of results! ASSuming you are still alive.

KuulKuum · Nov 6, 2015

This ^

https://www.youtube.com/watch?v=ZjXK8Vhm4Po

Timlindz · Nov 6, 2015

Lol

this is perfectly acceptable two 400v fuses taped end to end then cut the last one in half for 200 volts and tape it to either end of the last two you put together and it should work fine. oh by the way be sure and use electrical tape instead of duct tape don't cut cost there because duct tape is only rated to 375.256 volts.

TurpoUrpo · Nov 6, 2015

Mate, You should not make jokes on this subject when OP is so clearly out in the wild with regards to electrical engineering..

For OP. Correct fusing is never too expensive. If your(/your companys) project is over budget, its becouse budget was done by totally incompetent people and they should carry the responsibility and that means they should really not think about cutting safety short.

Mickey · Nov 6, 2015

I'm not sure we should be joking about this subject. There are some very green students who visit this site.

Edit: TurpoUrpo types faster then I do.

RoTaTech · Nov 6, 2015

http://https://sp.yimg.com/xj/th?id=OIP.M934d4a5a0fcf64bd9f5a01a7b204444fo0&pid=15.1&P=0&w=300&h=300

fuses in series to increase rated voltage?

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