Class T vs ANL fuse

[John Frum]

A similar rated Class T fuse will break in something like 0.02 seconds at 1000A - an order of magnitude faster.

How fast will a semicondutor fuse trip?
My BMS is configured to trip on short circuit current in ~.0001 seconds.
"3.1.10.2 Hardware Short circuit Protection
Provides instantaneous short-circuit current protection. The delay should be no more than a few hundred
microseconds." -- https://raw.githubusercontent.com/F...ter/Overkill_Solar_BMS_Instruction_Manual.pdf

 

[upnorthandpersonal]

How fast will a semicondutor fuse trip?
My BMS is configured to trip on short circuit current in ~.0001 seconds.
"3.1.10.2 Hardware Short circuit Protection
Provides instantaneous short-circuit current protection. The delay should be no more than a few hundred
microseconds." -- https://raw.githubusercontent.com/F...ter/Overkill_Solar_BMS_Instruction_Manual.pdf

Yes, there is a hardware short circuit protection in the BMS - and yet, I've had a class T fuse react before that circuit reacted.
I'll have to add it to my list of things to do: investigate how the circuit is implemented on the JK and JBD/Overkill...

 

[eemarty]

I ordered a pair of 180LET BS88 fuses from aliexpress for about $8 each a few months ago and received them.

 

[John Frum]

I ordered a pair of 180LET BS88 fuses from aliexpress for about $8 each a few months ago and received them.

Does 180let decode to anything?

 

[Hedges]

https://www.digikey.com/en/products/detail/eaton-bussmann-electrical-division/180LET/1876565

https://www.eaton.com/content/dam/eaton/products/electrical-circuit-protection/fuses/bussmann-series-catalogs/bus-ele-cat-1007-flc-2018.pdf

180 amp, "LET" series. See page 89

$8 vs. $135
(I'm not sure if we should laugh at them, or they are laughing at us.)

 

[12VoltInstalls]

180 amp, "LET" series. See page 89

$8 vs. $135
(I'm not sure if we should laugh at them, or they are laughing at us.)

So I’m trying to interpret.

Am I correct in saying you do not have faith in these import Class T fuses?

Because at $8 I might want some on hand!

I bought a three-pak 125A Class T fuses from a US supplier after significant searching for $120; $40 each.

Considering chinese-sourced commodities at minimum quantities listed are typically US-stock retailed at ~1000-2000% markup (before duty etc) I’m curious ($40 is only ~500%).

 

[Hedges]

Exactly.
I'm trying to figure out if $135 fuses sold in the U.S. are sourced from China for $8,
or if that is a worthless $8 knockoff of a $135 fuse.

For $8 each, can afford to blow a couple testing them. But I don't have a way to test at high current.
The fuse/breaker tester I built uses a transformer to multiply current from space heaters & variac. I can dial in the Arms I want but not more than a couple hundred amps. Might be able to get 1000A or so with suitable loads.
This could let me measure trip time and resistance vs. time, but not anything near AIC limit nor DC interrupting capability.

Midnight's paper described a bank of car batteries for DC testing.

 

[12VoltInstalls]

Exactly.
I'm trying to figure out if $135 fuses sold in the U.S. are sourced from China for $8,
or if that is a worthless $8 knockoff of a $135 fuse.

You got it.

Related, but different field:
I discovered I can buy lanthanated tungsten TiG electrodes for US 30c each for a reasonably small single order of 250 pieces, packaged in plastic protector cases. Made in China. Weeks to arrive but it’s chinaco so maybe risky.
Yesterday the welding supply truck sold me an identical plastic pak of ten with the sticker on it only different in that it has a major brand name, mailing address, and a web url with their logo. Same font, “made in China.” $54.99 plus tax. Not game changing money but it’s my money and it hurt my feelings.

If those $8 Class T’s are any good it would be nice to know. Very nice to know.

 

[DPC]

Pretty common to use something to quench an arc.

Some fuses have a filler material that produces gas when an arc is struck and this gas blows out the arc...
Other have silica sand in them that will melt and insulate and cool the arc .

Chinese fuses 10 times cheaper than a brand name from a reputable retailer.
Yikes.
From the people that brought you the fire cracker the cheapest fuses you can buy....

 

[Hedges]

Can you test the impact on weld quality?

Sometimes, that takes decades to surface. And $Billions to address.

https://inis.iaea.org/collection/NCLCollectionStore/_Public/23/075/23075921.pdf

"Unfortunately the detrimental effects of copper and phosphorus upon irradiation embrittlement has not been recognized earlier and the RPV steel generally of many older reactors has high concentration of these impurities. In particular, this situation is pronounced in the case of weld metal. The steel filler material used in the fabrication of older submerged arc welds was often copper plated to enhance electrical contact during welding and resistance to corrosion during storage. The copper content in the welds results directly either from the copper plating or the residual copper in the steel filler material or both."

Embrittlement of welds in nuclear reactor containment vessels, due to copper plating on welding rods.

 

[Hedges]

Chinese fuses 10 times cheaper than a brand name from a reputable retailer.
Yikes.
From the people that brought you the fire cracker the cheapest fuses you can buy....

You mean like "Bussmann"?

Eaton Bussmann fuse China plant

Cooper xian fusegear, an important manufacturer plant for Bussmann fast acting fuse and time delay fuse.Ask ABPower any bussmann fuse.

bussmannpower.com

genuine or fake bussmann fuse

How to tell genuine or fake Bussmann fuse, NH fuse, 170M fuse comparation

bussmannpower.com

 

[DPC]

scary stuff

 

[KITROBASKIN]

Hope this is legit; We have one and are not going to test it...

South Bend Components

https://www.amazon.com/dp/B0BQZ9LHFF?ref=ppx_pop_dt_b_asin_title&th=1

From product description:
¨Used as OEM material in Thor and Forest River RVs.¨

 

[Hedges]

If you review the trip curve and find "guaranteed not to blow" current/time, you could design a non-destructive test.
Modest overload for short enough time before turning back off, pulse of stored energy for large overload short time.
Perform 4-wire resistance measurement. I expect positive TCR, heads toward runaway. Scope required for fast pulse.

I realized I might be able to do DC test with 3 phases of transformer to boost current, and rectifiers.
Given a 3-phase source. At this time, all I have is Sunny Island 40~50A continuous, 180A 30 ms.

Single phase AC, I now have 25kVA 240/480 to 120/240 transformer. Could wire that as 5:1 step-down autotransformer.
52A continuous through each primary winding, 260A output. (Resistive load regulates primary current, e.g. 3 or 4 space heaters.)

Fed by 125A branch circuit breaker, should be able to draw 4x (500A) briefly, deliver 2500A for a fast-trip test. Enough for a 400A breaker.
To non-destructively test fuses, maybe put a one-shot pulse into SCR, synchronized to line voltage.

 

[DPC]

Reminds me of the joke about the discount visectomy

Only after you pay and your strapped on the gurney do you find out the nurse is holding a pair of bricks

I would spend the time buy known fuses from a known supplier

 

[12VoltInstalls]

Reminds me of the joke about the discount visectomy

I thought the joke about the discount vasectomy had a punchline like your wife not being forgiving that you had to pay child support to her sister…

 

[12VoltInstalls]

Can you test the impact on weld quality?

The tungstens are the electrodes in TiG. You’ll know as soon as you strike an arc if they are not what they’re supposed to be.

Standard ER70S-x is still all copper coated rods btw, and you can still buy 2% thorium tungsten electrodes….

 

[A.Justice]

Reminds me of the joke about the discount visectomy

Only after you pay and your strapped on the gurney do you find out the nurse is holding a pair of bricks

I would spend the time buy known fuses from a known supplier

Turns out your doctor was trained in India, and was doing the exact same surgeries 3 months ago over there for 1/10th the price. ?

 

[DPC]

Turns out your doctor was trained in India, and was doing the exact same surgeries 3 months ago over there for 1/10th the price. ?

My Doctor retired.
He was a 70ish Jewish man with a calm way of speaking.
He was good at telling jokes and stories that did not go anyplace.

What he was really doing was assessing me in a way that did not make my blood pressure rise!
Jabs and cortisone injections, sample pills sometimes given for free to try...
He worked in the USA and Canada and had seen a lot of the world.
He was really good at what he did. ( had some funny jokes about interactions with the local mortician he does not like )
And his plane receptionist with a slightly less than happy demeanour always got me in to see him when I needed too.
The lobby had uncomfortable steel office chairs and usual assortment of national geographic magazines from 20 years ago.
No TV and a hand full of old toys to keep young children quiet.
This is how Socialized medicine is supposed to feel ( the warmth and inviting feel of the lobby of sausage factory..... In and out but no sitting around )

Enter new guy.
He's french with all the personally of a polished dress shoe.
He looks at the computer and orders tests and does not talk to me.
He asks me what I want rather than suggest what I need.
There is a chesterfield in the lobby, gas fireplace, TV set WIFI in the lobby, your going to be waiting here....
The office staff now all look under 20 and they are smoking hot girls that gossip and shuffle papers, and useless as boobs on a nun...

You know I end up going to a clinic now instead, short waits and better outcome.
There is this Indian Doctor at the one closest to my house.
Doctor Moe..
He talks, tries things and isn't afraid to actually do something in his office that the family doctor says I need to see a specialist for.
I see him less and get well faster.
He is hard to understand though, explanations seem to take longer and there are no jokes. ( yet I suspect he might be funny its hard to gauge )
Number one things is IN and OUT.
Not waiting around or waiting to get in or waiting period.

If thats Indian doctors, open the flood gates let them in...

 

[12VoltInstalls]

chesterfield in the lobby…smoking… girls

you mean the cigarettes with ‘micronite’ asbestos filters?