Author Topic: EEVblog #1152 - 240V-120V=Magic Smoke  (Read 2762 times)

0 Members and 2 Guests are viewing this topic.

Offline DocBen

  • Regular Contributor
  • *
  • Posts: 79
  • Country: de
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #25 on: December 07, 2018, 12:28:01 am »
Had to check my ERSA Analog 60.
Primary fuse.  :-+

The Weller is probably "designed by intern (TM)"  :wtf:
 

Offline NANDBlog

  • Super Contributor
  • ***
  • Posts: 4100
  • Country: nl
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #26 on: December 07, 2018, 01:03:34 am »
Had to check my ERSA Analog 60.
Primary fuse.  :-+

The Weller is probably "designed by intern (TM)"  :wtf:
It is the cost cutting. It's a 100 dollar soldering station, where the iron itself is 55 dollar. The same company sells sidecutters that cost more. I dont really understand why they marketed as the grey series (professional) instead of red series (consumer)  but after seeing the review and seeing this video... I really dont understand. I mean, maybe they make 10-20 EUR on each sale, selling an iron which is terrible, further eroding the name, and whoever buys this, doesnt going to buy tips by the dozen to make up for it with the profit.
 

Offline EEVblog

  • Administrator
  • *****
  • Posts: 27235
  • Country: au
    • EEVblog
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #27 on: December 07, 2018, 01:14:44 am »
You can't really blame Weller for this mistake or any other manufacturer for that matter where products are imported from elsewhere and then used in countries that they were not intended or designed for. To help minimise the chance of this happening again Weller could easily add a warning label near the IEC connection, perhaps users could also be more diligent and add their own big bold warning sticker to the front of odd equipment as a permanent reminder and to alert other users who may not be aware of the products origin.

Except for when the primary fails due a manufacturing fault or other failure and then melts down and catches on fire with the regular 120V input.
Not having at least an internal thermal fuse in the primary is just bad design practice, possibly against standards, and increases company legal liability. i.e. they didn't use industry standard "best practice" and very deliberately cost cut at the expense of basic safety.
 

Offline EEVblog

  • Administrator
  • *****
  • Posts: 27235
  • Country: au
    • EEVblog
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #28 on: December 07, 2018, 01:18:11 am »
Product brochure/Datasheet says nothing about approvals but some disti marketing says says "UL and CE listed."
UL Certifications Directory I could not find Weller or Cooper Tools, they might not use UL?

If it says UL listed then it must actually be registered with UL. You could get it ETL tested for example to the same UL standard, but you cannot say it's UL listed.
It has the UL listed mark on the bottom.
Have you checked "Apex Tool Group"?
« Last Edit: December 07, 2018, 01:19:53 am by EEVblog »
 

Offline Muttley Snickers

  • Supporter
  • ****
  • Posts: 1832
  • Country: au
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #29 on: December 07, 2018, 01:24:17 am »
I agree that the primary lacked any form of even basic protection but as that aspect was already mentioned numerous times both here and in the comments I didn't bother repeating it, they should still add a rear label to stop idiots just adding a bigger fuse should it keep blowing.
One smart cookie, better make that two for good measure.
 

Offline NANDBlog

  • Super Contributor
  • ***
  • Posts: 4100
  • Country: nl
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #30 on: December 07, 2018, 01:26:00 am »
Product brochure/Datasheet says nothing about approvals but some disti marketing says says "UL and CE listed."
UL Certifications Directory I could not find Weller or Cooper Tools, they might not use UL?

If it says UL listed then it must actually be registered with UL. You could get it ETL tested for example to the same UL standard, but you cannot say it's UL listed.
It has the UL listed mark on the bottom.
Have you checked "Apex Tool Group"?

This is the UL listing:
https://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/showpage.html?name=KQLR.E18708&ccnshorttitle=Heaters,+Industrial+and+Laboratory&objid=1074016910&cfgid=1073741824&version=versionless&parent_id=1073989224&sequence=1
 

Offline DocBen

  • Regular Contributor
  • *
  • Posts: 79
  • Country: de
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #31 on: December 07, 2018, 01:39:55 am »
I think it is actually supposed to be a model for educational institutions. No worries they're just children.

Cant wait for marketing to rebrand it as their "outdoor activity model":
Outdoor because you're house will have burned down.
Activities:
Running (from the fire)
Swimming (to cool your burns)

 :-DD
 

Offline SeanB

  • Super Contributor
  • ***
  • Posts: 14965
  • Country: za
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #32 on: December 07, 2018, 02:49:21 am »
Take the Hakko fake and use the transformer in it for a replacement. Probably the same size or at least will fit, and will most likely also have a primary side thermal fuse in it, and then you can transplant the secondary side PTC with a new solder in back up fuse. then mark it as a 240V unit and keep it around. Probably cheaper than a new Weller transformer.

However I remember a very expensive mistake made, where there were identical power outlets next to each other, and the only differentiation between them was the labelling. One was a 16A 400VAC 50Hz 3 phase plus neutral and PE, and right next to it on the wall, identical blue IEC socket outlet, was a slightly different supply, 16A 115VAC 400Hz 3 phase plus PE aircraft ground supply, provided from a rotary converter in the complex. Brand new apprentice, first day there, and told to " take this trailing lead to the wall ( vague gesture to wall with 2 sockets next to each other) and plug it in", and brand new apprentice does so, and the in charge turns on the aircraft, turns up the ground air supply to max cooling, gets out the cockpit and they go to lunch, as it takes around 40 minutes for the avionics to power up and complete self test and self alignment from cold.

They come back from lunch, walk in the door and are greeted by the sight of the aircraft drooling the magic smoke from every opening, vent and cowling. much talk and analysis, and the conclusion was that " Box, electric centre, protection relay" that was supposed to not connect power unless it was within 100-135VAC 360-445Hz with all 3 phases present, did not work correctly when presented on the sense inputs with 380VAC 50Hz, and did not disconnect the power relay.
« Last Edit: December 07, 2018, 03:04:03 am by SeanB »
 

Offline Dave

  • Super Contributor
  • ***
  • Posts: 1128
  • Country: si
  • I like to measure things.
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #33 on: December 07, 2018, 04:06:00 am »
The  cores would do the "60 hertz  hum  of death!"
That would actually be the 120 Hz hum.  ;)

Magnetostriction only cares about the absolute magnetic field density, which has two peaks in one sine period, therefore double the frequency.
<fellbuendel> it's arduino, you're not supposed to know anything about what you're doing
<fellbuendel> if you knew, you wouldn't be using it
 
The following users thanked this post: Kilrah

Offline floobydust

  • Super Contributor
  • ***
  • Posts: 1826
  • Country: ca
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #34 on: December 07, 2018, 04:07:18 am »
I've asked Weller why the station does not have a fuse on the primary and if I can purchase a jar of magic smoke  ;)
Will update if I hear from them.
A complaint can also be filed with UL/CSA, if S/N and model # are submitted.

I've gone through this before and it's quite disappointing due to politics.

Assuming a mistake has been made- in product design, or assessment or applying the incorrect safety standard, or an omission in that particular standard:
-A manufacturer would have to issue a product recall.
-The regulatory Agency contract waives all liability or responsibility on their part. I find they (i.e. UL) does not admit anything as nobody wants egg on their face, tarnishing their reputation :-X. They may offer a free re-assessment of the product.
-Contacting the IEC standards committee- the bureaucracy is impossible to navigate and they are no different in that a stupid/missing clause takes years to get introduced.

It might be a manufacturing error in Mexico. There is no place to solder a fuse at the xfmer primary terminals. The (secondary) fuse+PTC combo is proof an idiot was involved. I know a fuse is required on the primary, it's even common sense.
 

Offline chris_leyson

  • Super Contributor
  • ***
  • Posts: 1082
  • Country: wales
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #35 on: December 07, 2018, 07:04:30 am »
That's a seriously bad design, it isn't a manufacturing error because you can see that the connectors on the wiring looms fit exactly where they should. It's a serious design error where cost down has taken priority over safety. Any reputable company would do open and short tests on wiring looms, connectors and even individual components on PCBs. I have to do that with my designs, not literally shorting each component but making sure that worst case combinations of opens or shorts result in a safe failure that isn't going to cause a fire or electocute the end user. Looks like Weller don't take much care or don't show any due diligence when it comes to safety.
 

Offline blacksheeplogic

  • Regular Contributor
  • *
  • Posts: 212
  • Country: nz
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #36 on: December 07, 2018, 09:06:09 am »
I agree that the primary lacked any form of even basic protection but as that aspect was already mentioned numerous times both here and in the comments I didn't bother repeating it.

It is interesting that when I checked my 120V & 240V Weller stations I have all appear to be fused on the primary. Would have expected therefore that this would have been just BAU across their line.
 

Offline thm_w

  • Frequent Contributor
  • **
  • Posts: 842
  • Country: ca
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #37 on: December 07, 2018, 09:10:45 am »
That's a seriously bad design, it isn't a manufacturing error because you can see that the connectors on the wiring looms fit exactly where they should. It's a serious design error where cost down has taken priority over safety. Any reputable company would do open and short tests on wiring looms, connectors and even individual components on PCBs. I have to do that with my designs, not literally shorting each component but making sure that worst case combinations of opens or shorts result in a safe failure that isn't going to cause a fire or electocute the end user. Looks like Weller don't take much care or don't show any due diligence when it comes to safety.

Good point, there is a very small chance the 4A fuse is on the primary in the original design and whoever drew the manufacturing drawings really screwed up. But seems unlikely.

What is the point of having a 7A SRF and and 4A fuse in series :palm:
I can't see this making any sense unless they expected the heat from the transformer to couple into the SRF somehow?

https://www.digikey.ca/product-detail/en/bourns-inc/MF-R700/MF-R700-ND/259979
 

Offline mikeselectricstuff

  • Super Contributor
  • ***
  • Posts: 11619
  • Country: gb
    • Mike's Electric Stuff
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #38 on: December 07, 2018, 09:38:46 am »
From https://weller-tools.com/we1010na/
Quote
Safety: WE1010NA has numerous features that will reduce potential hazards throughout your workday. It features a reinforced safety rest that provides extra stability when storing the iron between uses. The cables of the iron are also heat-resistant and meet industry standards for mechanical strength. The unit is also ESD safe and UL and CE certified for electrical safety.
:-DD :-DD
Youtube channel:Taking wierd stuff apart. Very apart.
Mike's Electric Stuff: High voltage, vintage electronics etc.
Day Job: Mostly LEDs
 

Offline Deodand2014

  • Contributor
  • Posts: 27
  • Country: au
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #39 on: December 07, 2018, 12:08:03 pm »
For what it's worth, a repair/upgrade video might be interesting. I have an old AC adaptor that has 240V input on the primary to output 24V @ 50a on the secondary I'm willing to sacrifice.
 

Offline EEVblog

  • Administrator
  • *****
  • Posts: 27235
  • Country: au
    • EEVblog
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #40 on: December 07, 2018, 12:32:40 pm »
FYI, I've contacted a director at Apex Tools, will see if I get any response.
 

Offline Brumby

  • Supporter
  • ****
  • Posts: 7895
  • Country: au
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #41 on: December 07, 2018, 01:52:20 pm »
Dave - have you checked your PO Box mail in the last day or so...?
 

Offline floobydust

  • Super Contributor
  • ***
  • Posts: 1826
  • Country: ca
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #42 on: December 07, 2018, 01:56:49 pm »
To be fair, Hakko FX has MET Labs approvals file E212152 for UL 499 Electric Heating Appliances, CSA C22.2 No. 122 Hand-Held Electrically Heated Tools.
These are different safety standards than what Weller has EN 60335-1, -2-45.

Hakko B3722 PC Board with Fuse for FX-888D. Seems like a good idea. Will it fit in the Weller?  ;D

edit: added pic
« Last Edit: December 07, 2018, 03:52:34 pm by floobydust »
 

Offline SparkyFX

  • Regular Contributor
  • *
  • Posts: 213
  • Country: de
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #43 on: December 07, 2018, 06:24:12 pm »
My unsorted thoughts on this:
Any fuse you add primary would need a certain voltage and current rating that is oriented on the devices operating voltage. So you´d have to install a 240V fuse in the 120V device... just in case?!
Taking it ad absurdum what if someone connects 750V? Nothing against good quality fuses, but they would need mystery rating for inrush current and voltage - to be safe against this mistake.

The 120V transformer has half the amount of primary windings a 240V model would have at the same output VA, but at a bigger cross sectional area (thicker gage). The inrush current is therefore a lot higher than nominal, and especially higher when it goes in saturation.

A fuse itself would not protect a damaged transformer from overheating, insulation faults can overheat and burn at nominal current (the short being of unspecified resistance - worst case scenario). At the same time fuses could blow because an intact transformer was switched on at extreme outside conditions... like cold temperature, high grid voltage. So one would need a very slow fuse, but when that opens, the insulation might already be partially damaged and the device is a ticking time bomb.

I reckon there is no perfect protection in this case, might be the best alternative to have the transformer short out and melt all of its insulation, as long as there is no particulary flammable material around it. The winding insulation´s physical properties (melting point, conductivity) has the biggest impact of all protective measures. Unfortunately it also means that the insulation should not degrade much or loose these properties when aging. Fuses do not have this problem, but they don´t help much with less than ideal shorts.

edit: I´ve got to admit if it would happen to my gear i would equally ask for more protection components. The outcome however shows a few things:
- Lab did not burn down
- Device is defective and will cause house installation breaker to open
- Transformer is fully shorted, not partially

Most people would replace a primary side fuse with a higher current rating, which would not make the device safer at all, but the existence of a fuse might make the transformers insulation cheaper by manufacturers design decision. Then the part could really burn down the house. A huge part of this safety relies on the house installation being up to code. That´s a questionable way of handling the devices safety, but in the end an inspector needs to check what caused the issue and would it have been caused with a different device on the same outlet. If the installation is not up to code you´ve got a problem.

Imho the real mistake is here: 120V device in 240V Australia, featuring an IEC-C13 connector! Leaving that connector away would reestablish safety by having the proper, incompatible plug.
« Last Edit: December 07, 2018, 07:27:05 pm by SparkyFX »
 

Online BravoV

  • Super Contributor
  • ***
  • Posts: 5421
  • Country: 00
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #44 on: December 07, 2018, 06:32:34 pm »
Just for comparison at old genuine Hakko 936 controllers, one is rated for 230V but for 50Hz, and another for 220V but 60Hz.

As Dave said ... "they did pay attention to the detail", just watch the fuse spec at the white warning label.  :-+



Offline capt bullshot

  • Super Contributor
  • ***
  • Posts: 1260
  • Country: de
    • Mostly useless stuff, but nice to have: wunderkis.de
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #45 on: December 07, 2018, 07:47:51 pm »
Such stuff has to be tested to achieve CE / UL whatever.
I guess it has been tested for secondary shorts and overload, that's the way the secondary fuse and polyswitch creeped in. From my experience with testing according to standards (whatever standard applies) today, everyone does test exactly what the standard and auditor requires, but nothing more. So, in case the standard didn't require testing a 120V unit at 240V mains, no one would have tested that.

Here, where I'm working, one can see strange things happen.

For example, someone designs a flyback converter for a 24V to 12V (plus several auxiliary voltages)  conversion, it's a flyback because isolation is required and it's always been a flyback for that kind of application.

Now, some testing happens. Someone else discovers, the transformer runs hot if one of the auxiliary outputs is shorted or overloaded. The flyback isn't designed to go into hiccup mode then (for unknown reason, or maybe just ignorance), so the transformer runs too hot. Now an protection circuit gets added to each auxiliary output that shuts down the converter in case of overload or short. Test passed then, everything is fine, converter board costs more than planned - no one cares now. Only the orignal designer was pushed to reduce cost, not the other ones that added the protection circuit.

This converter circuit get reused once. Someone discovered the controller doesn't limit the output power in case of the main output is overloaded. By chance, the original designer was asked and added a clever workaround at minimal cost. Test passed, everything is fine.

Not this converter, including all the protection circuitry plus the original designers clever workaround gets reused again, by some new designer who isn't familiar with the original designers intents. The circuit just gets copied, for some reason a new transformer is designed (smaller than the orginal one), and one auxiliary supply is removed. So the removal of this auxiliary output also removed the snubber circuit (one more clever idea of the original designer was to use the primary snubber as an auxiliary output) - a new snubber circuit is added to make it work again. This circuit gets tested and someone else discovers the primary controller doesn't shut down it the main output is overloaded. The original designers clever workaround is still there but doesn't work here because of the new transformer or whatever. The one who is testing doesn't know about the clever workaround anyway, so he adds another (complex looking) protection circuitry that isn't working on the first try, so a respin is needed. Finally test passed, everything is fine.

Result: a very compicated looking schematic of an rather simply flyback supply. Best part still to follow: At some point the requirement for isolation was dropped, input and output GND were bonded together and the whole thing could have been done with a way more simpler buck regulator.  :palm: :palm: :palm:

So, I'm really not surprised at all by the missing primary fuse and the bullshit polyfuse / fuse combination on the secondary with this transformer.
Safety devices hinder evolution
 
The following users thanked this post: Kilrah

Offline EEVblog

  • Administrator
  • *****
  • Posts: 27235
  • Country: au
    • EEVblog
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #46 on: December 08, 2018, 12:43:47 am »
The 120V transformer has half the amount of primary windings a 240V model would have at the same output VA, but at a bigger cross sectional area (thicker gage). The inrush current is therefore a lot higher than nominal, and especially higher when it goes in saturation.

A fuse itself would not protect a damaged transformer from overheating

Of course it would, that's why it's standard practice in almost every other bit of mains power gear in existence.
A correctly sized and typed fuse would be guaranteed to break with 240V on a 120V primary, or a gross failure in the 120V primary under normal supply.
Use a slow-blow if you are worried about inrush current.
 
The following users thanked this post: thm_w

Offline thm_w

  • Frequent Contributor
  • **
  • Posts: 842
  • Country: ca
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #47 on: December 08, 2018, 10:15:52 am »
My unsorted thoughts on this:
Any fuse you add primary would need a certain voltage and current rating that is oriented on the devices operating voltage. So you´d have to install a 240V fuse in the 120V device... just in case?!

120V fuses are generally capable of handling 240V as-is, no need to overrate. Its not like it would *operate* at 240V, its blowing in 5s or less.

https://www.digikey.ca/product-detail/en/bel-fuse-inc/3AG-15-R/507-1629-ND/1009968
 

Offline Kilrah

  • Supporter
  • ****
  • Posts: 1564
  • Country: ch
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #48 on: December 10, 2018, 11:10:34 pm »
Not having at least an internal thermal fuse in the primary is just bad design practice
You did not completely tear down/unwind the transformer, I would expect there to be one in the center. It likely just needed a few more seconds to trip since the whole mass has to heat up (one can see only the outer layer really got hot, the center windings don't have damaged insulation yet).

The thermal fuse is there more as a long term overload protection, not really appropruiate for this case although it's likely it would have tripped before things got melty enough to affect outside stuff (smoke is impressive, but it takes a lot more heat before there is a real risk of setting external stuff on fire).
This really needs a fuse on the input. Pretty crazy, never seen a direct input in a long time even on the cheapest Chinese crap I have.
 

Offline SparkyFX

  • Regular Contributor
  • *
  • Posts: 213
  • Country: de
Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #49 on: December 11, 2018, 06:00:58 am »
Hope this is not seen as pedantic, i just think it is a good conversation.

Of course it would, that's why it's standard practice in almost every other bit of mains power gear in existence.
A correctly sized and typed fuse would be guaranteed to break with 240V on a 120V primary, or a gross failure in the 120V primary under normal supply.
Use a slow-blow if you are worried about inrush current.
I think of such systems more as a question of overheating protection than the current itself as feedback... comparable to a motor protection that needs to match the installed motors size to trip even below the nominal electrical current for the given wire gauge when running in overload-condition... therefore potentially overheating the winding insulation. Temperature sensors/fuses in the windings are of course another, more telling option as a protection.

Long story short: The operational range of an electrical (melting) fuse just does not 100% overlap the operational range of a transformer, simply because the mass of the fuse and the mass of the coil are drastically different and any designed protection can only be as good as the specification of the error it should avert. I reckon no one foresaw to run it at 240... too bad it has the IEC connector in the back that allows it. Operating devices outside their spec is a killer to the question of which approvals the device has.

Floobydust pointed out the differences which approvals were applied, so if i would need to guess, this soldering station was probably classified as a heating device, where the risk of overheating prevails the electrical dangers (again, current is a weak indicator for heat produced). Maybe such a classification is a sneaky way around the need of a fuse.

The requirements of intra-device protection and those of house installation protection also vary heavily by country (e.g. over here for house installation the fuse dimensioning is dependent on the surrounding material or air the cables are covered in by a correction factor).
But i never understood the legal binding of these approvals, although i think i get what is tested or approved there.

There are quite some open questions, like if the detachable supply cable is part of the device (an internal fuse will not protect of a damaged cable).

120V fuses are generally capable of handling 240V as-is, no need to overrate. Its not like it would *operate* at 240V, its blowing in 5s or less.
The design intent of a fuse is more or less shifting the big part of the voltage drop from a circuit to the fuse, therefore dissipating most of the power there, therefore "blowing" at a rated speed. Some loads however expose different dangers and fail different than just by overcurrent. At best a fuse would protect the internal wiring excluding the transformer... but there is no metal case, although there is ground.

A 120V fuse will presumably have no problem of shutting down the nominal 230/240V by air gap. But when talking about transients or arc flashing, when connected to such a grid i´d expect them to have higher requirements = higher price, even though there is no CAT rating on the device. Should the fuse arc over, it wouldn´t open the circuit. Maybe i see this too narrow, as if considered only in high energy networks.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf