EEVblog #1160 - Weller Responds

[EEVblog]

I have a WES81 230V version and it has a IEC power connector with integrated fuse. So do they only use a primary fuse on the 80 watt model and not on the 50W? Or do they only use a fuse on the 230V model and not on the 110V? Is it only fused for the EU market? 

Someone on Youtube said their EU unit does not have a fuse, but I have yet to see actual visual evidence of this.

[rsjsouza]

Comment from Youtube:
Can anyone confirm?

Nothing freely available out there...

One aspect I haven't seen in this discussion is the toxicity of the components of the burning enamel. I suspect this is not qualified by the certification agency (maybe the wire manufacturer) but, for someone like me that always lived with respiratory problems, having a massive ejection of fumes is a health hazard.

Oh well... Fuses FTW.

[EEVblog]

I am not a transformer guy, but my second thought was: Wouldn't the transformer saturate (with 240v), and blow the fuse quickly?

Yes, that's what happened, except that there was no fuse, so the transformer heated up within seconds and melted all the insulation, which started to short out the turns causing more power to be delivered.

[EEVblog]

One aspect I haven't seen in this discussion is the toxicity of the components of the burning enamel. I suspect this is not qualified by the certification agency (maybe the wire manufacturer) but, for someone like me that always lived with respiratory problems, having a massive ejection of fumes is a health hazard.

I immediately put my lab carbon filter on full and left it on for a few days.

[floobydust]

Sometimes a manufacturer will certify to an old lazy safety standard because it's easier- cheaper and quicker way to get product to market.
Regional differences, between North America UL 499 and rest of the world EN/IEC 60335 are probably the reason a fuse may or may not be seen.

[timelessbeing]

UL 499 is an antique safety standard from an era where soldering irons were just a power cord and a handle with heater.... But here we have a power transformer (component) which can fail partial shorts (shorted turn on primary or secondary)

And the heater was .... a coiled up resistance wire (capable of partial shorts.)

not a dead short but rather a fire hazard

I wasn't aware that copper and steel were flammable.

the transformer draws high current and heats up.

kind of like a heating appliance.

[thm_w]

its not on the 'wrong side'. You put them on both sides if you want, its better. Plenty of documentation on there. But you always want it on the front side.

You are missing the info from the previous thread. They are using two fuses in series, one is suspiciously mains rated and UL listed, one is not. In this case it makes zero sense to have two fuses in series. Therefor, the mains rated fuse is on the wrong side (according to me).

What's crazy is they have no less than 2 fuses and a massive polyswitch on the secondary side. Not all of those are needed, and that extra secondary fuse could have paid for the primary fuse. It's wacko.

yep, the polyswitch is functionally useless. It will never do anything, unless the air near the transformer secondary somehow heats up enough to trip it, which it won't, because its not thermally coupled.

Agree on this being deliberate, but they are probably saving more than ten cents.
As their secondary protections are hand-mounted, "flying" stuff, they chose not to put those on a PCB with better mounting.
At the primary side, they would have had to use either a mains socket with a built-in fuse holder (which are significantly more expensive) or mount the fuse holder properly (a primary side fuse on flying wires... yuck!) with maybe a total added cost of a few dollars if you count parts and added labor...

This is the first argument that makes sense to me. They had designed the 4A fuse to go on the primary, then it was too costly or labor intensive to find a way to mount it on the primary. Or maybe the regulations do not allow that. So, someone moved it over to the secondary. Ok that is still hard to believe.

[lowimpedance]

Put in a thermal fuse in the transformer and achieve the same end with out burning down the owners home/work.

Would it respond fast enough? Dave said this went up in seconds.

Smoke perhaps, what about actual flames and heat ??, which a thermal fuse would presumably be the proper choice as opposed to just a regular fuse.
They do come in different temp and current ratings.

[David Hess]

Smoke perhaps, what about actual flames and heat ??

The lack of flames is a small consideration when the self extinguishing materials they used are spewing bromine compounds into the air.

[JustMeHere]

Comment from Youtube:
Can anyone confirm?

I've skimmed the IEE document.  Frequently used is the term "rated voltage supply".  It says stuff like the coil should not get to hot when use at "rated voltage supply".  They also say "normal use" a good bit.  It looks like the overload only needs to protect an overload of 1.1x "rated voltage supply" and "normal use" is used in that section too.

In general plugging a 120v rated device into a 240v supply seems to invalidate the protections dictated in the document.

[Grapsus]

Here is a WSD50 from 1999 still going strong.

Like many pepople here I used to have a lot of confidence in this brand as a brand making solid tools that will outlive you with spare parts available.
It really doesn't matter if it's legal or not to omit the primary fuse. The fact that they cut a corner where even chinese clones don't dare to do it means that this company has gone to shit.

[PartialDischarge]

That symbol states that the transformer is safe to short-circuit or overload at the secondary. The IEC 61558 norm gives tables as to the maximum temperature it may reach, it may be classsified as inherently or non-inherently short circuit proof, depending on if the temperature self regulates or there is a protective device, and thats what the ptc and fuse are doing at the secondary.

I dont see how this protects fails at the primary and makes the use of a fuse unnecessary

[Uncle Bob]

I have a WES81 230V version and it has a IEC power connector with integrated fuse. So do they only use a primary fuse on the 80 watt model and not on the 50W? Or do they only use a fuse on the 230V model and not on the 110V? Is it only fused for the EU market? 

Someone on Youtube said their EU unit does not have a fuse, but I have yet to see actual visual evidence of this.

I'm new here but I am trying to upload a picture of the inside of my WE1010 bought here in Sweden in October.

[lowimpedance]

Smoke perhaps, what about actual flames and heat ??

The lack of flames is a small consideration when the self extinguishing materials they used are spewing bromine compounds into the air.

That maybe, but isn't all the talk about fusing which would hopefully have mitigated the emissions to some extent to start with.

[santiall]

Comment from Youtube:
Can anyone confirm?

yes, that's correct and also that a mains fuse isn't compulsory as long as other safety requirements are met.

in your case, I guess the test would be happening under 'abnormal operation conditions' and in some cases also under 'reasonably foreseeable misuse' where it is expected that someone could set a voltage selector in the wrong position or insert a battery backwards. I'm not saying that this station complies or not but I'd not be surprised if it passes the tests even there is 'a bit of smoke' as long as there was no fire or explosion.

It may also well have happened that the transformer has been preapproved so there are some tests that are taken as a pass even if in this particular use case it may have occured a fault.
Also take into account that in the past the safety requirements for NA (USA + Canada) could have be more relaxed than now and since those stations are intended for 120V, and they don't have voltage selector (do they?) they may just assume it is simply not possible for anyone to use them at 240V in the intended market.

I'm speculating a bit, I'm far from an expert in safety standards, but as per my experience the situation can be quite convoluted and there are many ifs, could, should...

[EEVblog]

I have a WES81 230V version and it has a IEC power connector with integrated fuse. So do they only use a primary fuse on the 80 watt model and not on the 50W? Or do they only use a fuse on the 230V model and not on the 110V? Is it only fused for the EU market? 

Someone on Youtube said their EU unit does not have a fuse, but I have yet to see actual visual evidence of this.

I'm new here but I am trying to upload a picture of the inside of my WE1010 bought here in Sweden in October.

Thanks. Any fuse further in the primary wiring?

[EEVblog]

I'm speculating a bit, I'm far from an expert in safety standards, but as per my experience the situation can be quite convoluted and there are many ifs, could, should...

Which is why any company with any sense what so ever just puts a primary mains fuse. Even the cheapest of cheap crap has one.

[cdev]

Read whats also changed/changing (legally) in my post from the other day on the law and economics movement. (in 'Dodgy Technology') It's quite a significant, global change.

(How scary that this policy also seems to apply to 'reactors' - I see the atomic symbol on the transformer!)

[EEVblog]

Someone questioned Weller and got a more detailed reply from a product engineer (specific to Australian supplied units).
Guess he didn't get the "don't say anything" memo:

Thank you for contacting Apex Tool Group.
The only Weller soldering tools fitted with fuses at all are the soldering stations.
The WES51D, WESD51D have an internal fuse on low voltage side of the transformer on the circuit board. The new WE station has a fuse on the low voltage side of the transformer.
The WD series and other German designed stations have a fuse on the high voltage side.
None of the hand held line voltage soldering tools have fuses and all are compliant to the Australian standards and have Australian electrical approval.
There is no requirement in either Australian or international standards to fit a fuse to the primary circuit.
This is no different to any number of other products that also have transformers include literally millions of plugpacks, TV’s, radios, Stereos, battery chargers and other small appliances, very few of which contain primary fuses.

[Richard Crowley]

Using a global-standard IEC 60320 C14 power inlet on a gadget hard-wired for 120V seems like just asking for trouble.
Where is is trivial to plug in your power cord from whatever your local mains voltage is.

https://en.wikipedia.org/wiki/IEC_60320#C13/C14_coupler

[coppercone2]

how easy are they trying to make it for manufacturers lol?

Now that I think about it I took apart a old linear power supply wall wart without any fuses in it that had the mains soldered directly into the transformer primary (110V). I thought it was just because it was real old.

[EEVblog]

Using a global-standard IEC 60320 C14 power inlet on a gadget hard-wired for 120V seems like just asking for trouble.
Where is is trivial to plug in your power cord from whatever your local mains voltage is.

Exactly, especially with the voltage label on the bottom. Why any engineer or large company like this selling professional products to a professional market would go out of their way to avoid a fuse in such a product is beyond me.

[EEVblog]

Now that I think about it I took apart a old linear power supply wall wart without any fuses in it that had the mains soldered directly into the transformer primary (110V). I thought it was just because it was real old.

Very often they have thermal fuses built into the transformer, so it's not immediately obvious.

[jmaja]

Now that I think about it I took apart a old linear power supply wall wart without any fuses in it that had the mains soldered directly into the transformer primary (110V). I thought it was just because it was real old.

Very often they have thermal fuses built into the transformer, so it's not immediately obvious.

What's the difference of having a thermal fuse and not having a fuse at all, BUT making sure there is no fire or electrical hazard? Once the thermal fuse is blown 99+% of users still need to buy a new one, since they are not able to replace the fuse inside the transformer.

Having a fuse that can be easily replaced is another thing. Then you may have gotten away with by just replacing the fuse.

The questions are.
Is it possible to make a transformer safe without a primary fuse?
Is this Weller safe?

It gave some smoke out, but was there a real possibility of a fire or an electrical hazard?

[coppercone2]

Generally having voluminous turd masses expanding in your chassis should be avoided in a quality product. Of course its not safe it made a shit load of easily preventable toxic smoke.

Can you really engineer something like that right, burning foam expanding crap acting as a safety barrier from shorts to the chassis?? It's alot of weird systems to trust (insulation type, wire type, the brown enclosure box type, can it push the crimps off possibly? Etc). Manufacturing wise your process of making that transformers failure mode act like a safety feature is unreasonably hard compared to using a fuse.

Also, it popped his breaker. Breakers are not supposed to be triggered as a safety feature. They can over heat and you should do your best to not reduce the cycle life of a mains circuit breaker its important for building safety, plus it can cause all sorts of problems like fire alarms and building power problems, having to call a electrical or qualified personnel to reset a breaker (say in a school) leading to downtime and probably a room evacuation.