EEVblog #1160 - Weller Responds

[fsr]

Oh, yes, only the Germans protect their stations with a fuse: https://www.banggood.com/FX-951-Style-230V-AU-Plug-Solder-Soldering-Iron-Station-p-932704.html?rmmds=buy&cur_warehouse=CN 

Those are your words, not mine. Please note the context of my reply. I'm not sure I appreciate the context of replies being repeatedly changed to facilitate arguing against them.

Oh, well, if you meant something else, i didn't understood what it was. Sorry.

[Ian.M]

Using a 120 V unit at 240 V is not the typical failure case, and there is no complaint about the unit blowing up.

I don't know if anyone has brought this up yet so forgive me if I'm repeating something: could it be that the 120V models have to adhere to a safety standard which doesn't assume such fatal errors? The response from Weller seems to be 'the device adheres to safety regulations' (for the market it is sold in) and that is the end of the story.

If that is the case then IMHO that safety standard is defective due to the significant risk of 240V being applied to a 120V appliance if it is on a multi-wire branch circuit in accordance with US NEC 210.4(B).  All it takes is a high load on the other phase, and a high resistance or open neutral, which can be due to as small a defect as a loose or otherwise improperly applied wirenut.

[timelessbeing]

why do Weller have fuses on almost all of their other products which have identical functionality?

Simple. When you pay extra for a higher end station then you get more features, such as being able to keep your iron after stuffing too much voltage into it.

[nuclearcat]

Using a 120 V unit at 240 V is not the typical failure case, and there is no complaint about the unit blowing up.

I don't know if anyone has brought this up yet so forgive me if I'm repeating something: could it be that the 120V models have to adhere to a safety standard which doesn't assume such fatal errors? The response from Weller seems to be 'the device adheres to safety regulations' (for the market it is sold in) and that is the end of the story.

If that is the case then IMHO that safety standard is defective due to the significant risk of 240V being applied to a 120V appliance if it is on a multi-wire branch circuit in accordance with US NEC 210.4(B).  All it takes is a high load on the other phase, and a high resistance or open neutral, which can be due to as small a defect as a loose or otherwise improperly applied wirenut.

I am getting from time to time portable propane heater units from friends to repair. Units seems imported as second hand, from japan, japanese language everywhere.
They are all 100V and big transformer with lot of secondary windings(no SMPS shit). All of units are fused + MOV on high side, for overvoltage protection, and this scheme works perfectly (220V here, and mistakes happen a lot) saving the units all the time. After changing failed parts i remove plug and solder it to 220V/100V transformer directly
As with companies like Weller, they sell units that are barely changing for many years, despite technology evolved a lot (and recent amazing chinese soldering stations dave reviewed prove that), so Weller still have sales just because of their past reliability and reputation.
MOV cost $0.2 in quantity, fuse was mentioned as $1. Seems Weller reputation flushed to toilet because of this $1.2 .

[madires]

As with companies like Weller, they sell units that are barely changing for many years, despite technology evolved a lot (and recent amazing chinese soldering stations dave reviewed prove that), so Weller still have sales just because of their past reliability and reputation.
MOV cost $0.2 in quantity, fuse was mentioned as $1. Seems Weller reputation flushed to toilet because of this $1.2 .

Yep, nice executive summary of the issue.

[DL3CE]

For europe:

I only read citations because I didn't buy the original standard EN 61558 (a thing I hate with passion, since those standards are quasi-law, therefore they should be available for free..), but it seems that they are "safety transformers" which are short-circuit proof (the Weller transformer bears the symbol for this) and don't need to be fused, but one interesting point is, that they aren't allowed to have multiple primary voltages or, for non-mobile devices, they have to be changable only with specific tools.

So I think they totally knew that they will smoke if subjected to higher than normal voltage and forbade switchable input voltage since they thought of "choosing a wrong voltage" as an to be expected "oops". But "wrong voltage out of the wall socket" was "that won't really happen" ... I don't agree with that.

[floobydust]

Weller WES51 transformer is a different bird at 40VA. Previously a custom Tyco part, 4000 series 4000-01E07G827, Tyco 2-1611453-5, Class II UL1585. Get this from Tyco:
"Inherently Energy Limited Transformers - Class II transformers up to 50 VA are “Inherently Limited” which means that the transformer, if overloaded, will short itself out and fail safely, not requiring a fuse." 

Looking at IEC 61558 Transformer Safety, Part 15 on short-circuit testing and considering the WE1010 is almost twice the power 80-100VA would be a "non-inherently short-circuit proof transformer".

15.3.1  "The output terminals are short-circuited...."
15.3.2  "If protected by a fuse... the transformer is loaded for a time T and with a current equal to
k  times  the  current  marked  on  the  transformer  as  the  rated  current  of  the  protective  fuse-
link, where k and T have the values shown in Table 4." {This is 1hr at 210% rated unless the polyfuse is easier}

The safety standard fails to say where the fuse is located- at the transformer input or output winding.
Secondary fuses are downstream of both windings, thereby useless at covering a transformer (winding) fault.
The safety standard fails to state where the output terminals are- before or after the Weller secondary fuse bodge?

It looks like a vague, poorly worded safety standard that can get exploited. Engineers have to let common sense prevail and "fuseless technology" would make most of us gasp.
If you want to see the hazard, run the station on 120VAC and short the transformer secondary or load it at max. power. Then grab a coffee.

[TheDane]

<cut>
Looking at IEC 61558 Transformer Safety, Part 15 on short-circuit testing and considering the WE1010 is almost twice the power 80-100VA would be a "non-inherently short-circuit proof transformer".

15.3.1  "The output terminals are short-circuited...."
15.3.2  "If protected by a fuse... the transformer is loaded for a time T and with a current equal to
k  times  the  current  marked  on  the  transformer  as  the  rated  current  of  the  protective  fuse-
link, where k and T have the values shown in Table 4." {This is 1hr at 210% rated unless the polyfuse is easier}

<cut>

The transformer is not truly protected by a fuse if there is only a fuse on the secondary
- the secondary side fuse is protecting against overloads on the output, preventing a long term short-circuit of the output terminals.

Selecting the correct standard is not always easy, it requires extensive knowledge - and faults can be made. Responsible entities will correct their mistakes - will, well - or err?

[Asad]

As with companies like Weller, they sell units that are barely changing for many years, despite technology evolved a lot (and recent amazing chinese soldering stations dave reviewed prove that), so Weller still have sales just because of their past reliability and reputation.

Link?

[Quarlo Klobrigney]

When I was young, we didn't need no "fancy" soldering sticks. Heat came in 4 models. The extreme heavy duty, the heavy duty, the medium and the last for fine 0402 work.
If you lost heat change the tank, or plug it in. If you lost a tip, just make one up out of a #00 round copper buss bar, #10 or #12 wire. She'll be good as new.

[rsjsouza]

When I was young, we didn't need no "fancy" soldering sticks. Heat came in 4 models. The extreme heavy duty, the heavy duty, the medium and the last for fine 0402 work.
If you lost heat change the tank, or plug it in. If you lost a tip, just make one up out of a #00 round copper buss bar, #10 or #12 wire. She'll be good as new.

How far have we come... we didn't have the torch or the fancy guns (so expensive back then that it was relegated to the professionals), but we certainly has a 30W "stick" for the delicate jobs and a heavier 120W stick for the chassis' jobs.

[floobydust]

Both IEC 61558 and UL 1585 wrap the transformer in tissue/cheesecloth for the overload, heating, short-circuit (fire) tests, with 16A or 20A mains feed.

Confusion with the Class 2 "doorbell" transformers seems to also plague the safety standard.
These are energy-limited output by impedance or external secondary fusing, used for doorbells, zone valves etc.
Condo fire after a cable staple shorted out the 24VAC wiring and I found the transformer had improper secondary fusing. I had to design a replacement panel for that.

I've reached out to IEC and will see if the technical committee is approachable, to possibly patch the holes in the standards.

Weller needs to patch up their ethics or explain their hypocrisy- the WS81 and WD1 stations are the same power level and have a mains fuse.

[floobydust]

When I was young, we didn't need no "fancy" soldering sticks. Heat came in 4 models. The extreme heavy duty, the heavy duty, the medium and the last for fine 0402 work.
If you lost heat change the tank, or plug it in. If you lost a tip, just make one up out of a #00 round copper buss bar, #10 or #12 wire. She'll be good as new.

The good old 8200 soldering gun makes a few kV at the tip when you switch the trigger off! ZZzzzzt.
I killed a lot of solid-state electronics before realizing that one. The soldering gun is not earth-grounded and uses that solenoid-style transformer with tons of leakage inductance.
Never use one on modern electronics. A-OK for vacuum tube stuff 

[Electro Detective]

When I was young, we didn't need no "fancy" soldering sticks. Heat came in 4 models. The extreme heavy duty, the heavy duty, the medium and the last for fine 0402 work.
If you lost heat change the tank, or plug it in. If you lost a tip, just make one up out of a #00 round copper buss bar, #10 or #12 wire. She'll be good as new.

The good old 8200 soldering gun makes a few kV at the tip when you switch the trigger off! ZZzzzzt.
I killed a lot of solid-state electronics before realizing that one. The soldering gun is not earth-grounded and uses that solenoid-style transformer with tons of leakage inductance.
Never use one on modern electronics. A-OK for vacuum tube stuff 

I'll bet there was some FUSE wire in the switchboard just in case one of those "fancy free" 4  -pick a duty-  models    went south on a job,
or the cat or dog nibbled on the power cord   



----------------------------

To address earlier comment/s, unless the Weller transformer is an isolation welding class type with a 100% Duty Cycle on a dead short without too much temperature rise,
then it can't possibly be considered a 'Safety Transformer'

i.e. toast may/will happen eventually
and or the Fire Truck rocks up and a lecture comes your way after the water hoses and axes get packed away

Secondary fuse values F or T types aren't that difficult to work out,
it's every EE/manufacturers task to do that

and it's been done like many many many times before over the decades and documented,
so no mystery Dead Tech ancient scrolls to search for, buried in the ruins of Silicone Valley...   

[N2IXK]

Those old Weller guns also made a pretty good degaussing coil for working on color TV sets, too.

[ruffy91]

All those security standards assume a fault either in the transformer itself or downstream!
There is no way to protect the transformer of all upstream failure cases.
Just imagine they added a fuse. What should the voltage rating of the fuse be? 150V, 300V, 1kV? Also what should the interruption capability be, a few dozen ampere, 25kA? All those choices assume some upstream components (for example a defined maximum voltage, the maximum current the upstream breaker allows for a short time etc. everything defined in countless standards.)

All those assumptions do not apply when the device is connected to the wrong grid.

Should it also withstand to be connected to 15kV 16 2/3 Hz Bahnstrom and fail safely?

So you should search for the standard applied to the wiring which allowed 240V on a 120V device in the first place.
IMHO the connector is the root of all evil in this case.

[EEVblog]

As with companies like Weller, they sell units that are barely changing for many years, despite technology evolved a lot (and recent amazing chinese soldering stations dave reviewed prove that), so Weller still have sales just because of their past reliability and reputation.

Link?

[Brumby]

@ 10:32



There's the fuse.

[fsr]

All those security standards assume a fault either in the transformer itself or downstream!
There is no way to protect the transformer of all upstream failure cases.
Just imagine they added a fuse. What should the voltage rating of the fuse be? 150V, 300V, 1kV? Also what should the interruption capability be, a few dozen ampere, 25kA? All those choices assume some upstream components (for example a defined maximum voltage, the maximum current the upstream breaker allows for a short time etc. everything defined in countless standards.)

All those assumptions do not apply when the device is connected to the wrong grid.

Should it also withstand to be connected to 15kV 16 2/3 Hz Bahnstrom and fail safely?

So you should search for the standard applied to the wiring which allowed 240V on a 120V device in the first place.
IMHO the connector is the root of all evil in this case.

It's a 120v 70w soldering station. Probably a 0.8A fuse would be ok. Voltage rating is not a problem, because those IEC connectors are for single phase, and 240v is the maximum woldwide, right?
Now, if you connect it to 240v, it's going to draw a lot more current. At least twice the current. It's just a matter of choosing the right fuse.
It's not the only way the transformer can fail. Hell, the transformer can be faulty from manufacturing, and overheat after some time in use. Just imagine what could happen if a whole batch of this soldering stations had a fault like that!

[Quarlo Klobrigney]

I used one about 2 months ago because I forgot my coil at home and the customer was 50 miles away.. It worked a treat on an RCA CTC-9. A D550 though..
Quote from: N2IXK on Today at 19:22:11

Those old Weller guns also

made still make a pretty good degaussing coil for working on color TV sets, too.

[orion242]

Weller WES51 transformer is a different bird at 40VA. Previously a custom Tyco part, 4000 series 4000-01E07G827, Tyco 2-1611453-5, Class II UL1585. Get this from Tyco:
"Inherently Energy Limited Transformers - Class II transformers up to 50 VA are “Inherently Limited” which means that the transformer, if overloaded, will short itself out and fail safely, not requiring a fuse." 

Looking at IEC 61558 Transformer Safety, Part 15 on short-circuit testing and considering the WE1010 is almost twice the power 80-100VA would be a "non-inherently short-circuit proof transformer".

Both IEC 61558 and UL 1585 wrap the transformer in tissue/cheesecloth for the overload, heating, short-circuit (fire) tests, with 16A or 20A mains feed.

Confusion with the Class 2 "doorbell" transformers seems to also plague the safety standard.
These are energy-limited output by impedance or external secondary fusing, used for doorbells, zone valves etc.
Condo fire after a cable staple shorted out the 24VAC wiring and I found the transformer had improper secondary fusing. I had to design a replacement panel for that.

Thanks for some standards to look at.

I work in the class 2 world (<50vac <100va) and far as I recall NEC requires:  Under 100va low voltage cable can be used without any additional fusing, pretty loose regulations.  >100va requires fusing down to 100va per circuit or you fall outside of class 2.  At that point likely have to deal with things the same as 120vac mains wiring or close to.  Assuming there is some parity between feeding a listed device with a trany and including one in a product...

Seen many a class 2 trany with shorted secondary turn into a smoke bomb, never fire.  Seen them installed backwards by mistake as a step up.  That typically blows the living hell out of the end devices where the real fireworks show is.  Even in those cases, can't recall a trany fire, least none that didn't self extinguished when power was removed.  End devices...not spreading fire, at least in the cases I seen.  Stack flammable materials in the area, probably a bad day.  Soldering iron in a office space, not good.  Control systems on rated walls and concrete floors, usually not a building fire.

Closest thing in the US would be plugging this into a 240/277vac receptacle which is very different than 120v recp and unlikely in most residences.  Even in a lab setting, I assume these are rare and would clearly stand out.  Anyone even make a US 240v -> IEC cord?  NEMA 6-20P looks close to NEMA 5-20P but I'm guessing they cannot be interchanged.  So at least here, it seems it would take some real stupidity or a shared neutral circuit failure (as someone mentioned earlier) to bring on this fault.  The NEMA receptacles typically prevent this nonsense.  As bigclive calls it, a "death dapter" could certainly bypass NEMA designs, but that's still something that has to be a unicorn just thinking about the 240/277v recps I can think of.  That said NEMA far as I know, spells out different connections by voltage and current.  Little interconnection worries unless the install is borked or the end user goes out of their way.

So is a US vs international safety standard issue?  Does Weller sell this model in areas where 220/110v issue may really be a problem?  Or is it the IEC standard on the device that may allow for this?

[Ian.M]

Closest thing in the US would be plugging this into a 240/277vac receptacle which is very different than 120v recp and unlikely in most residences.  Even in a lab setting, I assume these are rare and would clearly stand out.  Anyone even make a US 240v -> IEC cord?  NEMA 6-20P looks close to NEMA 5-20P but I'm guessing they cannot be interchanged.  So at least here, it seems it would take some real stupidity or a shared neutral circuit failure (as someone mentioned earlier) to bring on this fault.  The NEMA receptacles typically prevent this nonsense.  As bigclive calls it, a "death dapter" could certainly bypass NEMA designs, but that's still something that has to be a unicorn just thinking about the 240/277v recps I can think of.

So is a US vs international safety standard issue?  Does Weller sell this model in areas where 220/110v issue may really be a problem?

Here's a US 240V to IEC C13 power cord for you:
https://www.amazon.com/NEMA-6-20P-C13-Power-Cord/dp/B004WJNVH4

If your bench has both 120V and 240V outlets and you've got any 240V only kit with an IEC C14 inlet, then there's a real risk of a mishap if you ever disconnect multiple items to move them, clean behind them etc.   

If I had IEC C13 leads in a US dual voltage environment, I think I'd spray paint all the 240V C13 ends bright red!

[orion242]

Closest thing in the US would be plugging this into a 240/277vac receptacle which is very different than 120v recp and unlikely in most residences.  Even in a lab setting, I assume these are rare and would clearly stand out.  Anyone even make a US 240v -> IEC cord?  NEMA 6-20P looks close to NEMA 5-20P but I'm guessing they cannot be interchanged.  So at least here, it seems it would take some real stupidity or a shared neutral circuit failure (as someone mentioned earlier) to bring on this fault.  The NEMA receptacles typically prevent this nonsense.  As bigclive calls it, a "death dapter" could certainly bypass NEMA designs, but that's still something that has to be a unicorn just thinking about the 240/277v recps I can think of.

So is a US vs international safety standard issue?  Does Weller sell this model in areas where 220/110v issue may really be a problem?

Here's a US 240V to IEC C13 power cord for you:
https://www.amazon.com/NEMA-6-20P-C13-Power-Cord/dp/B004WJNVH4

If your bench has both 120V and 240V outlets and you've got any 240V only kit with an IEC C14 inlet, then there's a real risk of a mishap if you ever disconnect multiple items to move them, clean behind them etc.   

If I had IEC C13 leads in a US dual voltage environment, I think I'd spray paint all the 240V C13 ends bright red!

That's not fitting a standard 120vac recp in the US.  It has the opposed blade which will not fit a standard 120vac 15A US recp.  The proper and closest equal are NEMA standards fittings I already quoted far as I can tell.  I assume there is a dimensional diff between them that makes them not interchangeable.

[Ian.M]

Of course it wont fit a 120V NEMA receptacle.  However it is sold and used in the USA , will fit the IEC C14 inlet on the offending Weller  soldering station and any other 120V kit with a C14 inlet, so  presents a risk of applying 240V to 120V only equipment.

IMHO the use of IEC C14 inlets for 120V only equipment that cannot withstand 240V without permanent damage, should be prohibited.   

[orion242]

> IEC C14

Exactly.  IEC failure, safety standards, etc.

Seems IEC is a bit too standard or the safety standards don't reflect the potential issues properly.  Wax on, wax off with the mains fuse aside.

Pointing blame at weller for selling a US specific model then somehow it gets exported...its their fault the product is placed in a condition it was never designed for.  Bit overkill IMO.  Fuse is cheap enough, so it seems silly to omit.  If they sell it world wide, shame on them for not adding a fuse.  Again, what are the real safety standards in this case??

If its a US only product, the chances of this happening are extremely low IMO.  Even at that, a class 2 limited trany as far as I have seen will put on a spectacular smoke show without fire.  So where really is the failure that allows for this?  Why is the primary fuse a choice is my question.