EEVblog #1160 - Weller Responds

[Ice-Tea]

They were drafting an electrical safety standard. Not a convenience standard.

This thread has nothing to do with "standards",

It doesn't? Weller claims it's a certified product and complies to applicable standards. So the that begs the question if that's correct or not.

it's here because:

a) Weller should know better than to sell an unfused device that could easily end up in a different country in 2018 (eg. ebay has been around for over 20 years).

Doesn't even have anything to do with 110/230V IMO. Stuff breaks, even when used on the correct voltage.

Anybody quoting standards at each other has clearly missed the main point.

Or, you know, people that are considering/quoting standards take it as a given that Weller did a dumbass thing, should burn on the cross for that but are still intellectually triggered by the underlying standards and reasoning...

[Fungus]

Louis Rossmann joined in the rant... check his YT channel. 

Haven't watched it, but I'm sure it's good 

Weller should be going into damage control soon.


I hadn't thought too much about that phrase in the Weller brochure. Let me reproduce it here for posterity.


I'm sure no comments are needed, it speaks for itself.

[Mr. Scram]

I have Weller WD1.
It has primary fuse and thermal fuse in transformer.
Problem is that 110V version specifies fuse of 1 A. 1A fuse will not blow if you connect 110V station into 240V in a time to save transformer.

Transformer might or might not overheat into short circuit. Some of them will just keep on smoldering. If primary wire is thin enough, it might even fail open.
Transformer wire coating is temperature resistant and flame retardant. If you heat it enough, it might char and become conductive, but not short, not immediately...
Current will rise slowly, until it finally either shorts, or breaks open.
If device catches fire it is usually case or something else made of non fire retardant plastic.
If exists thermal fuse will trip and kill off transformer. Thermal fuse is permanent disable, because if it trips, it is considered that temperature was so high that insulation of transformer was compromised, and should not be used anymore even if it seems to work.
Transformer can be designed to fail open.

Primary fuse is there mainly if short circuit does happen, and serves only to avoid your external fuse trip on a power distribution, so it doesn't shut off other devices.

Good point. The specified fuses on dual voltage devices tend to be different, so if people simply plug in the device into the wrong mains voltage a fuse may still not save the device.

[kosine]

May be different elsewhere, but 110V tools are actually quite common in the UK, even though our mains is 240V.

110V tools are used on construction and building sites, and have their own style of plug & socket. As a friend recently considered, there's nothing to stop people buying these tools on the cheap and swapping the plug for a domestic one.

Fortunately he asked about it first, but in light of the current discussion, I'm now wondering do these 110V tools have any additional protection in them as standard?

[coppercone2]

whats going to short out at 450W and current limit itself? :wtf

parts are just gonna fail to a happy impedance like that? its probably gonna trip. What part is going to make plenty of smoke like a giant transformer winding dissipating 500W @ 0.3 ohms on a 12V rail?

You've really never seen anything fail in a way that was not a direct, low-impedance short?   

why did it blow the breaker if its supposed to fuse??

Wait...  What?  Who blew what breaker now?   

did you read the discussion? someone said it could deliver 500W before it triggered a fuse. So you would have a short settle down to a stable 0.3 ohms before it tripped the fuse or LVSO ? If it goes under 0.3 ohms you exceed your wattage. What kind of short settles to 0.3 ohms and stays there for maximum power transfer?

[Grapsus]

From the amazon reviews:

August 7, 2018 : "Only used this iron for less than 2 months before the transformer blew up on me in the middle of an important job. Would not recommend."

https://www.amazon.com/gp/customer-reviews/R2E3U67D56PT9M/ref=cm_cr_dp_d_rvw_ttl?ie=UTF8&ASIN=B077JDGY1J

So maybe they're not using the best quality transformers out there...

Edit: also this one is suspicious

June 25, 2018: "IT STINKS!!

I had to store it outside in the shed when I first got it. It had a strong chemical odor and stunk up the room when used.
The plastic is still out gassing months after I bought it.

Other than that, it's OK."

https://www.amazon.com/gp/customer-reviews/R1T2PUCK5KWZA/ref=cm_cr_getr_d_rvw_ttl?ie=UTF8&ASIN=B077JDGY1J

Sure new plastic items smell sometimes, but this could also be the transformer heating.

[coppercone2]

NOTE: This message has been deleted by the forum moderator Simon for being against the forum rules and/or at the discretion of the moderator as being in the best interests of the forum community and the nature of the thread.
If you believe this to be in error, please contact the moderator involved.
An optional additional explanation is:

[drussell]

Maybe their customers are old-fashioned and think that heavy iron power supply = quality/reliability.

(there's already a few examples of that in this thread)

Are you saying that you have found small switchmode power supplies to be more reliable than a standard transformer?!   

[drussell]

(do you own wall warts with huge iron transformers in them?)

Absolutely.  Dozens, possibly hundreds of them.  I can count on my fingers without resorting to toes the number of times I've encountered a failed transformer-type wall wart.  The percentage would be a fraction of a percent of the total I've ever dealt with in my lifetime.

Contrast that with switchmode type wall-wart supplies, plug-packs and inline supplies.  I've seen more like hundreds of failures.  Guaranteed it is a double-digit failure rate percentage on average over the years.  Certain ones I have dealt with approach a 100% failure rate within the type.

Yes, most of these that fail are cheap junk and it is possible to build a good quality switching supply but it seems to actually still cost more than a small transformer type supply that lasts.  Even the best switchmode supplies have been far less reliable than a transformer supply in my personal experience.  YMMV.

I take it your experience is somehow completely different...  ??

b) The "requirement" will be that that devices fail safely, not that they must have fuses.

The reason fuses are being discussed here is that a fuse would be a cheap way to make Weller soldering stations fail safely. No other reason.

Dave's failed safely...   With a smoke signal saying, "ouch, you hurt me," to boot! 

[joeqsmith]

From Rossmann's video,  Pace tweezers may burn your hand if you use them all day...  I really like Pace's MT100 and am waiting to for them to release a version for their new station before upgrading.    Hope their new stations have fuses.

[drussell]

Fortunately he asked about it first, but in light of the current discussion, I'm now wondering do these 110V tools have any additional protection in them as standard?

I believe the idea is that they increase "safety" by supplying the upstream power for these tools from a center-tapped transformer with the center tap grounded, creating a 55-0-55 power supply, keeping the voltage to earth at a safer 55 volts AC from ground instead of 240.

[drussell]

did you read the discussion? someone said it could deliver 500W before it triggered a fuse. So you would have a short settle down to a stable 0.3 ohms before it tripped the fuse or LVSO ? If it goes under 0.3 ohms you exceed your wattage. What kind of short settles to 0.3 ohms and stays there for maximum power transfer?

I was talking about a PC 12V power supply being able to deliver enough power to create smoke.  Period.  This was a standalone point, not related to any prior specifics in the thread except the fact that some people seem to be implying that no failure of any device may ever be permitted to expel smoke, magic or otherwise.  My point was that attitude is misguided and unachievable.

[paschulke2]

"We will change the world & Own The Bench":

https://media-weller.de/weller/data/CMS%20Bilder/Rueckblick_productronica/Distributor%20Day%20Productronica%202015_External.pdf

[cdev]

The picture illustrates graphically why soldering stations should ALWAYS be fused, even if increasingly brain dead legislators rubber stamped a likely industry written change that allows them to not fuse some of them.

[Robaroni]

This is why I retired, people astound me!
Plug a station into 240 volts that's designed for 110 and it burns up. First if they fused the secondary side (I don't know either way) it would still burn up
if you plugged it into 240v.

Did you ever wonder when you see a warning on a package that says something like, "don't put your hand into the flame you might get burned!" And you think who could be so stupid to stick their hand into a flame?  Don't be surprised if you see a warning on Weller stations saying, "Don't plug 120v stations into 240v you could burn up the station!"

So there's smoke, gee I wonder why! I doubt it will catch fire the wire coating is usually fireproof so eventually it will melt away, the primary resistance will drop and the wire itself will melt just like the millions of wall transformers that are not fused.

So the fuse IS the primary winding and if you plug it into 240 you deserve to burn up the station.
I have a $900 Weller station - it will never see 240v. It's electronics it's my field, I'm buying an expensive station!

Let's blame Weller for my stupidity.

By the way it's a great station with long lasting tips in lots of styles.

[TheDane]

Must be isolated from mains - expensive

You think switch mode supplies aren't isolated from mains?

I know a lot about switch mode design. I have designed both isolated and unisolated types, and know about each type BOM and cost price.

It is absolutely possibly to make a SMPS that is unisolated from mains, but then there is added danger to the end-user - safety concern, which is also an added expense. 
https://en.wikipedia.org/wiki/Switched-mode_power_supply#Types

Please note the differences between Non-isolated topologies and Isolated topologies

[Robaroni]

The picture illustrates graphically why soldering stations should ALWAYS be fused, even if increasingly brain dead legislators rubber stamped a likely industry written change that allows them to not fuse some of them.

That would happen regardless if it was fused or not. The fuse would only work if the iron got down to some point on the board where it caused a short. But look at the picture, does that look like someone who should own a soldering station or anything that gets above 20C?

[TassiloH]

So the fuse IS the primary winding and if you plug it into 240 you deserve to burn up the station.

Of course the soldering stations might be safe in the sense that they won't catch fire, probably the transformer will smoke and draw more and more current until the wire melts someplace or the current is so high that it trips the circuit breaker. As long as the enclosure plastics is flame retardant and is not melted yet when this happens, the device is safe.
But consider this: Here we have 3-phase power to almost all buildings. It is rare but not unheard of that a neutral connection fails somewhere. Depending on the load distribution, this will give you almost 400V instead of 230V on the outlets - no stupidity involved. I would prefer equipment that either just burns a fuse or breaks without emitting lots of smoke (e.g. transformer with thermal fuse) in that case regardless of regulations, and I'd say it is not an unreasonable expectation that brand name stuff satisfies this.

[eugenenine]

Weller should be going into damage control soon.


I hadn't thought too much about that phrase in the Weller brochure. Let me reproduce it here for posterity.


I'm sure no comments are needed, it speaks for itself.

This is probably why it took so long for a response, (Weller) legal had to make sure they had documentation showing UL test passed = safety

[drussell]

That would happen regardless if it was fused or not. The fuse would only work if the iron got down to some point on the board where it caused a short. But look at the picture, does that look like someone who should own a soldering station or anything that gets above 20C?

I think you missed the tongue-in-cheek satirical humour on that one...   

[floobydust]

Let's be careful, if that's possible with all the flames here.

There are component-level certifications for a power transformer, like UL 1411, UL 506, CSA 22.2 No.66 and ‪IEC 61558. We don't know this transformer's approvals.
There are product-level safety standards for soldering irons, audio-, radio-, and television-type appliances, IT equipment etc.
There are regional differences in safety standards between North America, Australia and Europe as well for the component's and the product itself.

It makes a complicated soup.

Weller safety cert. for Europe is IEC 60335, and the 240VAC transformer pic https://www.eevblog.com/forum/blog/eevblog-1160-weller-responds/msg2051086/#msg2051086 shows a third bobbin lead, surely a thermal fuse is in there. 60335 does not specify a mains fuse but calls 61558 for the transformer's requirements.

Weller safety cert. for North America is UL 499. A different standard with different requirements, although the confusion around other soldering stations incorporating a primary fuse begs the question of WTF. UL 499 seems for higher power heaters and the mains breaker is the protective element.
At the 80VA power level, it is not an "energy-limited" transformer (Class 2) or "fail-safe".


This was not a "normal use" scenario as defined in the safety standards - but it did flush out an error in the product's safety.
Is there a safety hazard running it off 120VAC? Of course. I've seen three power transformer fires in electronics gear, quite a mess of smoke, soot and carbon.
Notice other safety standards IEC 60950 and 61010 require a fuse (DUH!) and (torture) load test a transformer for "maximum heating effect" limited by the fuse if there is one:

IEC 61010
9.6 Overcurrent protection     
9.6.1 General       
"Equipment intended to be energized from a MAINS supply shall be protected by fuses, circuit-breakers, thermal cut-outs, impedance limiting circuits or similar means, to provide protection against excessive current being drawn from the MAINS in case of a fault in the equipment."

4.4.2.7  MAINS transformers
4.4.2.7.1 General       
"The secondary windings of MAINS transformers shall be short-circuited as specified in 4.4.2.7.2, and overloaded as specified in 4.4.2.7.3.

4.4.2.7.3 Overload       
Each untapped output winding, and each section of a tapped output winding, is overloaded in turn one at a time. The other windings are loaded or not loaded, whichever load condition of NORMAL USE is less favourable. If any overloads arise from  testing in the fault conditions of 4.4, secondary windings shall be subjected to those overloads.

Overloading is carried out by connecting a variable resistor across the winding. The resistor is adjusted as quickly as possible and readjusted, if necessary, after 1 min to maintain the applicable overload. No further readjustments are then permitted. If overcurrent protection is provided by a current-breaking device, the overload test current is the maximum  current which the overcurrent protection device is just capable of passing for 1h. Before the test, the device is replaced by a link with negligible impedance. If this value cannot be derived from the specification, it is to be established by test.

For equipment in which the output voltage is designed to collapse when a specified overload current is reached, the overload  is slowly increased to a point just before the point which causes the output voltage to collapse.
In all other cases, the loading is the maximum power output obtainable from the transformer.

Transformers with overtemperature protection which meets the requirements of 14.3 during the short-circuit test of 4.4.2.7.2 need not be subjected to overload tests. "
----------------------------------
In all likelyhood, UL 499 has been wrongly interpreted/assessed or is simply antique.
A modern safety standard like 61010 and 60950 requires a fuse, which is what I go by.

[thm_w]

Thank you for contacting Apex Tool Group.
...
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.

When is the last time anyone has seen a plugpack with a transformer inside? Every major brand is using SMPS now due to standby power regulations (and cost). A modern TV without a fuse, what?
The cheapest of crap might have a fusible resistor instead of a glass fuse, but that is better than nothing (and probably questionably certified). Toaster is really the only thing I can think of that is a modern device without a fuse (that I am aware of).

This guy is living 20 years ago.

[jmaja]

"Equipment intended to be energized from a MAINS supply shall be protected by fuses, circuit-breakers, thermal cut-outs, impedance limiting circuits or similar means, to provide protection against excessive current being drawn from the MAINS in case of a fault in the equipment."

So a fuse is not required. The task described can be achieved even with unspecified "similar means".

[SeanB]

I have taken apart lots of assorted wall warts, and every one with a small iron core transformer had, buried in the primary winding either in the middle (with a 130C rating) or on the outside (with a 110C rating) a non resettable thermal fuse. Many different Chinese manufacturers, and even some Korean ones ( Samsung) along with some locally made ones. Those also had built in mains filters and phone line protection ( and 1mm of separation from mains live or neutral, depending on how the assembler felt that day for the phone line protection), and they all had mains fusing on the primary side. While the diodes on the secondary side could look like charred blobs, the filter capacitors look like well cooked sausage ( complete with domed top and bottom rubber extruding) and be brittle as anything they still worked, and shorting the secondary would just result in the primary side eventually popping, meaning another trip to find a replacement.

Even clock radios with the mains transformer as part of the line cord have this fuse built in. That Weller does not simply means this was a grandfathered part, you probably find this part number is the same transformer ( 110VAC 24VAC 60W) used in 1956 in the first WTCP soldering stations, and has never in all the decades been upgraded part wise, because it was tested then, the design did not change, and the original test certificate is still in an archive somewhere.

Standards may have changed, but rarely do they require you to redesign existing parts. You can still buy E27 stove fuses, despite the common circuit breaker having been de facto the go to part for the last half century, and there probably are still brand new stoves made with those screw in fuses in them, just the same old model of industrial cookware that has literally had standards written around them.

Then again, I do have some very old control relays, dating from the 1980's, that I use as spare parts donors, and a good number have unfused  110VAC primary transformers in them, might just take one outside, connect it to a somewhat dodgy mains connection, or find a 11 pin base and plug it in correctly and power it up with the relay cover removed. Toss up if the transformer will fail or if the Siemens capacitors on the power supply will blow up first, or if the 555 IC in some will survive 30V till something fails. Outdoors, because there will be flames, spitznsparken and possibly confetti generation. Mains protection is a 20A CBI residential breaker, and upstream is a 100A Heinemann breaker, with the substation 220m away having a 400A fuse on this phase. I think the little mains cable I intend to use will pop first.

[Robaroni]

So the fuse IS the primary winding and if you plug it into 240 you deserve to burn up the station.

Of course the soldering stations might be safe in the sense that they won't catch fire, probably the transformer will smoke and draw more and more current until the wire melts someplace or the current is so high that it trips the circuit breaker. As long as the enclosure plastics is flame retardant and is not melted yet when this happens, the device is safe.
But consider this: Here we have 3-phase power to almost all buildings. It is rare but not unheard of that a neutral connection fails somewhere. Depending on the load distribution, this will give you almost 400V instead of 230V on the outlets - no stupidity involved. I would prefer equipment that either just burns a fuse or breaks without emitting lots of smoke (e.g. transformer with thermal fuse) in that case regardless of regulations, and I'd say it is not an unreasonable expectation that brand name stuff satisfies this.

I don't know how Weller addresses 230V stations. They may simply tap off one side or phase and if the center leg opens the station loses voltage too. What happens with wall transformers where you are? Do you get smoking transformers? If what you're saying is true then a neutral leg failure would be doing major damage with appliances wouldn't it? Does Weller make 3 phase stations? I took a quick look and all I see are single phase.

I have transformers here that work on 120 or 230. All you get are two wires to the transformer with dual windings. How you run those windings (series or Parallel) determines the input voltage. I would think Weller probably does it pretty much that way saving money on different transformers.