New generation fusible links.

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steptoe
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New generation fusible links.

Post by steptoe » Tue Nov 09, 2010 9:31 pm

About a year ago I had grief with coroded FL's in my L series , and two years before that in my 84 Brumby.

Someone suggested using the new generation of plastic box enclosed FL's (known as FFL's Female Fusible Links) as they just clip in place of originals. I bought some off a travelling auto elec guy only to find they are 32? Volt rated so an 80 A 32V would give different rating at 12V wouldn't it? 240 Amps?? Don't think I know where they are now anyway.

http://www.circuitprotection.ca/fuseology.html answers the question above. It is OK to use higher Volt rated fuse in lower Volt applications

Again, just today I felt a momentary ignition like baulk or cut out as I was cruising light load. Yet to check the replaced FL's for any corrosion or their integrity. Certainly do not want a repeat of last year as it caused a high voltage spike and fried many circuits under dash, behind dash and all light bulbs frazzled

Any time this happens in my car I get shakey, anyone elses car I feel quite fine :)

I need to visit an auto elec or supercheap for correct voltage and amps units to try. (EDIT 08APR2012 - SCA FL also rated at 32V ) Also considering a rewire of ignition supply, new wires connections and relays as a switchable back up just in case my 24 year old gives up ghost. Time to hoard tools and spare ignition module as another be prepared sort of thing, or update cars.

Handy link to Narva site fuselinks info

http://www.narva.com.au/products/browse/metal-manual

SORRY, this is manual fuse ciruit breaker - still gets you there , just look at fuse links female

.....

showthread.php?t=14769

is where it all began for me.

new question for the electricians out there

what does continuous Amp rating mean or refer

is that short for a 20A fuse has a 20A continuous Amp rating?

...............
so it looks like - correct me if I am wrong, don't blame me if I am wrong, just thinking out loud on the white board (or dry erase for the US readers)

BLACK FL genuine with 1.25mm is 24A continuous amp rated (can't find 24A plastics, 30A?)
RED FL genuine with 0.85mm is 18A contiuous amp rated (so ? 20A in plastic)
GREEN FL genuine with 0.50mm is 13A continuous amp rated ( not found 15A in plastics eithe

the subie colours are different to the Narva fuse wire codes if compared with cross sectional dimnsions

........................

narva web site under fuses > link > wires give the rating of wire colours and cross sectional dia.. I matched the 1.25mm to the little 2


HERE

http://www.narva.com.au/products/browse/fuse-link-wire

......................

From the FSM

0.5mm green, woven fabric insulation Fusible link should melt within 15 seconds at a current flow of 80 amperes
0.85mm red, woven fabric insulation blah, blah, blah 130 amperes
1.25mm black, woven fabric insulation 190amperes

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steptoe
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Post by steptoe » Wed Nov 10, 2010 10:39 am

OK, popped into a place to buy a new gen fuse.

Labeled as 20 Amp Female Fuse Link - PLug In

I notice it is also marked 32V so I guess the ones I bought before yet cannot find! are OK to use in 12V application. I bought 20A as I know my stash does not include 20

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Post by steptoe » Wed Nov 10, 2010 11:35 am

showthread.php?t=14769

is where it all began for me.

new question for the electricians out there

what does continuous Amp rating mean or refer

is that short for a 20A fuse has a 20A continuous Amp rating?

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steptoe
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Post by steptoe » Wed Nov 10, 2010 11:58 am

so it looks like - correct me if I am wrong, don't blame me if I am wrong, just thinking out loud on the white board (or dry erase for the US readers)

BLACK FL genuine with 1.25mm is 24A continuous amp rated (can't find 24A plastics, 30A?)
RED FL genuine with 0.85mm is 18A contiuous amp rated (so ? 20A in plastic)
GREEN FL genuine with 0.50mm is 13A continuous amp rated ( not found 15A in plastics eithe

the subie colours are different to the Narva fuse wire codes if compared with cross sectional dimnsions

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Post by TOONGA » Wed Nov 10, 2010 3:37 pm

steptoe wrote:so it looks like - correct me if I am wrong, don't blame me if I am wrong, just thinking out loud on the white board (or dry erase for the US readers)

BLACK FL genuine with 1.25mm is 24A continuous amp rated (can't find 24A plastics, 30A?)
RED FL genuine with 0.85mm is 18A contiuous amp rated (so ? 20A in plastic)
GREEN FL genuine with 0.50mm is 13A continuous amp rated ( not found 15A in plastics eithe

the subie colours are different to the Narva fuse wire codes if compared with cross sectional dimnsions
Just curious as to where you got these ratings from, as Ive looked in the MY FSM Ive got and it didn't have rating specifications

and if they are correct I need to put in fusable links with lower amp ratings :rolleyes:

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Post by steptoe » Wed Nov 10, 2010 9:23 pm

narva web site under fuses > link > wires give the rating of wire colours and cross sectional dia.. I matched the 1.25mm to the little 2


HERE

http://www.narva.com.au/products/browse/fuse-link-wire

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Post by steptoe » Fri Nov 12, 2010 2:38 am

From the FSM

0.5mm green, woven fabric insulation Fusible link should melt within 15 seconds at a current flow of 80 amperes
0.85mm red, woven fabric insulation blah, blah, blah 130 amperes
1.25mm black, woven fabric insulation 190amperes

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Post by steptoe » Fri Nov 12, 2010 2:41 am

Need someone like Gannon to help understand all the above

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Post by TOONGA » Fri Nov 12, 2010 8:25 am

I understand it .... I think

if it is rated at 13 amps continuous then the fuse can take (voltage rating of fuse) volts at 13 amps or below 13 amps if the amperage rises above 13 amps then the fuse is designed to fail

look behind you its the parrot from the monty pythons sketch....

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Post by steptoe » Fri Nov 12, 2010 10:07 am

or 13 is 75% of what is marked on fuse and it blows at that rating?

So....13 is close to fifteen so we use a 20Amp fuse ?? then you look at blow at 80A for the 0.5mm 13A fuse...boggles my mind

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Post by steptoe » Fri Nov 12, 2010 10:08 am

Gannon is onto it.....

Hey

I glanced over it yesterday, but didnt post cos i was in a hurry to go see kevin Bloddy Wilson.

Basically, a 13A fuse will never blow if you put 13.1A through it.

Its called the I2t rule
Current (I) squared times Time (t)

The wire temperature depends on the current flowing through it and how long it has been flowing

It takes roughly 6 times the rated current to blow a fuse instantaneously, around 3 times the current to make it blow in roughly 10 seconds and at twice the rated current, it could take nearly a minute.

I have to leave for work, so i'll explain it better when i get home

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Post by steptoe » Fri Nov 12, 2010 10:17 am

So we have 1.25mm squared (black in subaru 24A) must blow after 190amps at fifteen seconds

So to get fifteen seconds blow time , four times the rating ? 190 divide by 4? 45A fuse link?

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Post by steptoe » Fri Nov 12, 2010 10:24 am

rang Narva technical and they are quite up front and open cannot help with converting one type to another due to risks involved if we stuff up and burn our cars - just in case

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Post by Gannon » Fri Nov 12, 2010 6:53 pm

If your 1.25mm fusible link is rated at 24A, replace it with either a 1.25mm fusible link or a 20A slow blow fuse or a 20A circuit breaker

My fuse times in the PM i sent you were only a guess.

Here is a diagram that shows the Current / Time characteristics of a 1A fast acting fuse.
Image

Substitute the 1A rating for whatever rating fuse you have and the time curve will be basically the same.

Read through this Circuit Protection

1.25mm cable is rated for 21A (at an ambient temperature of 40degC) so a 15A fuse is what you would use to protect it.

A 1.25mm fusible link should melt above 24A (it could take 2 days) and will definitely melt at 190A after around 15 seconds. A 300A fault might fuse in 5 seconds.

Either way, your choice will either be a 20A slow blow replaceable fuse, a 20A circuit breaker or a replacement 1.25mm fusible link.

This is a video i made to show what happens when you dont use the right sized fuse

I used a welder to put 120A through a piece of 16A rated house light wiring.
As you can see it didnt take long to go poof
http://www.youtube.com/watch?v=T8GiuM-gABY
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Post by steptoe » Sat Nov 13, 2010 1:54 am

OK, that was a cool segment, still got that plastic smell in your throat and schnoz?

Hmmm genuine application looking the safest simple bet here right now. These new fuse links not rated as slow blow. My problem may be ignition module causing a once off stutter just need to drive again with everything to change it on the spot if it happens again, - swap ig module anyway. All other ignition componets near new - 2500km old

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Post by phillatdarwin » Sun Nov 14, 2010 11:23 am

the amps are still the same as some times when i do testing i use a 2 amp 240 volt as a trip beaker on my test wire

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Post by Gannon » Sun Nov 14, 2010 9:37 pm

Yeah Phill it right.

A 30V 10A fuse will work equally as well at 12v

The voltage rating is its ability to prevent an arc from forming, possibly letting current to continue flowing, or destroying the fuse and anything around it.

I wouldnt use a 30V on a 120V circuit.
Current rides: 2016 Mitsubishi Triton GLS & 2004 Forester X
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Post by El_Freddo » Thu Jun 16, 2011 5:50 pm

Gannon wrote:Yeah Phill it right.

A 30V 10A fuse will work equally as well at 12v

The voltage rating is its ability to prevent an arc from forming, possibly letting current to continue flowing, or destroying the fuse and anything around it.

I wouldnt use a 30V on a 120V circuit.
To dig up an "oldish" thread:

I'm looking at finally replacing the fusible links with circuit breakers.

I can't remember what the ratings are for each of the green and black fusible links and the haynes manual is as useful as tits on a bull!

So what I'm asking is what amp rating circuit breakers should I be running for the black and green fusible links to make everything work properly?

I'm over fusible links!

*EDIT* ok, so this answers one of the circuit breaker ratings that I'll need, but what's the other one since I don't know what the fusible link rating is - and Ruby Scoo is 4km away to "just pop out and check it" :(
Gannon wrote:If your 1.25mm fusible link is rated at 24A, replace it with either a 1.25mm fusible link or a 20A slow blow fuse or a 20A circuit breaker
Cheers

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Post by Gannon » Thu Jun 16, 2011 7:36 pm

Just had a look at the 88XT FSM

The 2 green ones are 0.5mm2 and rated at 80A over 15sec
The red one is 0.85mm2 and rated at 130A
The black one as you know is 1.25mm2 and rated for 190A
The blue one is 2.0mm2 and rated for 260A
Current rides: 2016 Mitsubishi Triton GLS & 2004 Forester X
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Post by El_Freddo » Fri Jun 17, 2011 11:03 am

Thanks Gannon.

Ruby Scoo only has one black and three green. So I guess to get the correct amperage for the black unit I have to divide 190A by 4 which is 45A. Does this mean I need a 40A circuit breaker for the replacement of the black fusible link?

Thanks for your help - hopefully Jaycar will be open for me tomorrow while I'm off mountain.

Cheers

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