EEVblog #1160 - Weller Responds

[fsr]

You're asking for data showing that fuses work? 

Yes...  Data that shows that in this case, with the fuse that would be fitted by Weller, that is large enough that it would not cause nuisance fuse opens under normal operation in the long term at the usual 110-130 volts you see in North America, would always protect the transformer and not allow any smoke to escape when powered from 220-250 volts 50 Hz.

No need to prove that. You have a lot less chances of something going really wrong with the fuse in place.
Fuses don't blow in normal operation with correctmy designed equipment. Does that happen a lot to you?

[jonovid]

As far as the fuse blowing out of nuisance, I guess you have never heard of time delay fuses or resettable PTC's.

Not needed. Weller makes 110V soldering irons with fuses and nobody seems to be reporting that they're constantly blowing.

even if a resettable primary side fuse had failed to save the transformer from damage.
it would still have saved the lab from fire. had it been a careless operator that panicked!  did not disconnect the unit from the power source & just bolted out of the room, a failsafe, is a sign of a quality product IMO.

[Robaroni]

As far as the fuse blowing out of nuisance, I guess you have never heard of time delay fuses or resettable PTC's.

Not needed. Weller makes 110V soldering irons with fuses and nobody seems to be reporting that they're constantly blowing.

Mines not, which ones, how many and whose?

[glarsson]

For everyone defending Weller: Why has the more expensive Weller stations a fuse on the primary side if it isn't needed?

[eugenenine]

I don't argue that UL was performed well and a lot of products are UL conform.
I am just saying, a fuse is much better than an UL melting approved and specified procedure.

Sure its better, but its not required.  Many people say that self driving cars are better than non self driving, many people say that traction control, or automatic braking is better.  but there are many people who will buy cars without those features, usually due to cost.  But you can't say those cars are defective because they don't have a feature more expensive cars have.

A side effect of super cheap (usually china) clones is that people will see that the Weler (clone) is half the price of the (real) Weller so the real Weller looses sales and has to come up with a price reduced model to get some sales back or get run out of business.  So they cut costs wherever they can.  And as someone pointed out a fuse is just a thin wire and so is a transformer so if it passes UL (therefore legally safe) then thats what they have to do.

well when I was living there in US, in the one of my friend house this:

showed up in front of his home. My friend had to sayto them "sorry,  it was just a toaster". They were not happy and replied:" Next time you pay".
Since I love to cook, I often triggered the smoke alarm with wine or alcohol vaporated in a pan. I was surprised why no firetruck were showing up in my case.
Then I discover there was a faulty in the fire alarm sistem and my home was not radio connected with the firefighter station.

I assumed then all US fire alarm system should trigger a fire fighter truck close to the home.
Otherwise a smoke detector is there just for a beep-beep?

Nope, in the US its $ driven.   People want the biggest house for the cheapest amount of money so the home builder puts in the cheapest smoke detectors they can as long as they still meet the legal requirements.  If you want them monitored then you find a monitoring company (ADT for example) and pay them for a monitoring subscription.

Really no different than the Weller scenario here, lowest cost model gets the fewest features, want more (safety) features then pay more.

I am not an expert but is seems not enough for me. In my home I want the fire fighter running at full speed to my address in case of fire.

You would also want a way to cancel false alarms. 

But why would you want to wait for the fire department, why don't you have am automatic fire suppression system in your house?

[eugenenine]

For everyone defending Weller: Why has the more expensive Weller stations a fuse on the primary side if it isn't needed?

Why do more expensive cars have more safety features than cheaper ones?

[james_s]

My Goodman AC system has no fuse between 240V and its control xfmr. It costed me $5000 to install, and it came with a defective defrost controller board, and the new board has been ordered for a week and I still haven't seen it. As a result, I'm burning electricity on heating strips to keep myself from freezing.

Proudly made in USA.

Goodman is pretty much bottom of the barrel. It's one of those infamous brands that a lot of HVAC guys sneer at, although not surprisingly it's also one of the best selling brands out there because it's one of the cheapest. I made the mistake of installing a Goodman gas furnace years ago and it has been a hassle to keep it going.

[eugenenine]

even if a resettable primary side fuse had failed to save the transformer from damage.
it would still have saved the lab from fire. had it been a careless operator that panicked!  did not disconnect the unit from the power source & just bolted out of the room, a failsafe, is a sign of a quality product IMO.

or maybe, since the iron passed a UL safety test without a fuse, it wouldn't have burned down the lab even if it had been left plugged in.

[glarsson]

For everyone defending Weller: Why has the more expensive Weller stations a fuse on the primary side if it isn't needed?

Why do more expensive cars have more safety features than cheaper ones?

Because they are not required by law and it is cheaper to not include them.

[eugenenine]

For everyone defending Weller: Why has the more expensive Weller stations a fuse on the primary side if it isn't needed?

Why do more expensive cars have more safety features than cheaper ones?

Because they are not required by law and it is cheaper to not include them.

Same reason why a soldering station doesn't include it.

[floobydust]

For everyone defending Weller: Why has the more expensive Weller stations a fuse on the primary side if it isn't needed?

Any electrical safety standard will call for a mains primary-side protective element, in smaller gear.
Very few products (appear) to use nothing. From what I see...

The (North American) Weller is approved ONLY to meet the product-specific "soldering iron" safety standard UL 499 which has a few miscellaneous safety clauses. It does not fully cover basic electrical safety.

The (European) Weller approvals cover basic electrical safety IEC 60335-1 AND the product-specific part 2 IEC 60335-2-45 for the soldering iron aspect, AND calls a power transformer safety standard IEC 61558. So that product is probably safe - I haven't seen secondary-side fusing in pics, and assuming a legit agency did the assessment, not CE crap.

I'm not totally defending Weller, their electrical engineering dropped the ball but some blame is on a vintage safety standard that should be deprecated. 87 YEARS OLD is a safety standard long past its re-vamp. It allowed the engineering error to make it out to market. Or engineering designed it only to pass approvals.

Every Pace station has a primary fuse, but no mention of what UL/CSA standard they certify to, as a comparison.
Metcal/OK PS-900 no mention of its approvals and I did not see a teardown.
Edsyn has a fuse and no formal electrical approvals "COMPLIES WITH MIL-S-45743E, MIL-STD-2000-1B, WS6536E AND ESD SPEC, DOD-STD-1686, DOD-HDBK-263"

[glarsson]

For everyone defending Weller: Why has the more expensive Weller stations a fuse on the primary side if it isn't needed?

Why do more expensive cars have more safety features than cheaper ones?

Because they are not required by law and it is cheaper to not include them.

Same reason why a soldering station doesn't include it.

... and it shows how Weller values its customers.

[drussell]

Voltage doesn't enter into it. The fuse would be matched to the wire in the transformer.

Lets's say you put a 0.75A fuse in there.  How does the fuse know the difference between 90 watts (at 120 volts) being drawn, most of which is going into the actual iron element while it is heating, versus 180 watts (at 240 volts, which is still 0.75A) being dissipated solely by the primary winding of the transformer in a fault or mishap condition? 

That poor little primary winding isn't going to last very long dissipating even 180 watts.

Again, I'm not arguing that a fuse isn't a good idea and I would put a fuse in there if I designed it, but the people ranting about it automatically being a fire-breathing, smoke-emitting death trap just because it doesn't have a primary fuse and seem to think that adding a fuse would somehow solve all faults and potential failure modes that might emit some smoke or something are being at least a bit hyperbolic.

Fuses are not always required in the regulations because it has been deemed to not be necessary in all cases.  If there were any significant number of fires caused by things like this, it would be in the regulations.  The insurance industry (which is what started UL, of course) would see to it that it became a regulatory requirement if it was costing them any significant amount of money.

I'm not sure about 00 where you live, but in North America, it has been shown that things like bedroom fires caused by faulty line cords causing arcing or small smouldering below the limits that would trip the mains breaker was a larger problem than things like small transformers bursting into flames.  We are therefore now required to install Arc-Fault breakers on all bedroom circuits which are supposed to help protect against fire by trying to detect these kinds of conditions.

The UK has another approach which helps protect line cords and the connected devices by mandating fuses in every plug to help limit potential damage from their crazy 7700-watt-to-the-wall, double-connected, low impedance ring mains setup.  The same has not been deemed necessary in North America, apparently because there are not widespread problems with small transformer operated devices like this bursting into flames and burning your house down. 

[fsr]

Voltage doesn't enter into it. The fuse would be matched to the wire in the transformer.

Lets's say you put a 0.75A fuse in there.  How does the fuse know the difference between 90 watts (at 120 volts) being drawn, most of which is going into the actual iron element while it is heating, versus 180 watts (at 240 volts, which is still 0.75A) being dissipated solely by the primary winding of the transformer in a fault or mishap condition?

What makes you think that the soldering station will draw twice the power with twice the voltage? It seems to me that it's a lot more likely to just apply full voltage to the heating element until it reaches the set temperature, so, ignoring core saturation, it's double the voltage over a resistive heating element. That's 2 times the current and 4 times the power. The fuse will likely blow quickly under twice the maximum current draw.

For everyone defending Weller: Why has the more expensive Weller stations a fuse on the primary side if it isn't needed?

Why do more expensive cars have more safety features than cheaper ones?

Because they are not required by law and it is cheaper to not include them.

Same reason why a soldering station doesn't include it.

... and it shows how Weller values its customers.

Also, a fuse is very cheap for the safety it provides. Hardly an excuse to not include one. Very different from car security systems that are expensive. And even considering that, some car security systems are mandatory by law here since a few years ago, like driver and passenger airbarg, and ABS brakes.

[drussell]

What makes you think that the soldering station will draw twice the power with twice the voltage?

That was just an example, specifically to Fungus in response to his assertion that the voltage never ever matters in terms of fusing a transformer.

Of course a simple load will attempt to draw 4x the power at double the voltage but the real world is seldom quite that simple.  Even most small heating elements won't draw 4x the power since the resistance will usually rapidly rise as the temperature increases, and in the case of a controlled soldering station the unit may not even send any power to the iron upon power-up, depending on the state of the user controls or whether whatever control circuitry might exist is even receiving power if you blast it with twice the voltage.  It could blow regulators, microcontrollers, other components or whatnot meaning no power is ever even sent to the iron.

Since nobody has actually tested anything yet on this particular unit and provided any data, everything thus far is just pure speculation. 

[tszaboo]

You can blow up stuff with 1W of power with the right conditions.

That would be a feat. Please explain.

Actually, you can choke on your muffin for 0W.

It could be plugged into an IEC plug, so 16A and 240V could go into the box

You have 3800W available in a standard outlet shape? That's a bit worrisome. At least the iron would suffer a quicker, more humane death.

1W setting things on fire.

Yes, I have 3500+W in a standard outlet. Everyone in Europe has. https://en.wikipedia.org/wiki/Schuko
Why would that be worrisome? I also have 50KW electric motor in my car and the wires in the circuit breaker box can deliver 10.000A potentially.

For everyone defending Weller: Why has the more expensive Weller stations a fuse on the primary side if it isn't needed?

Why do more expensive cars have more safety features than cheaper ones?

And all new cars have ABS, ESP, airbag and seatbelt. And if a car doesnt have the advanced features,  they get lower score on Euro NCAP. So there is a third party, who tells them that it is OK, that these features are not mandatory, but your car is 0 star rating. And they publish this data. Just like Dave.
While it might not be mandatory to place a that fuse there, Weller gets 0 stars for this.

[HKJ]

You are missing a parameter, when the iron in the transformer is saturated the current is not just slightly higher, it is much higher.
I do not have a 120VAC transformer around or I could do a curve of current vs. voltage.

[floobydust]

Dave's 240VAC blunder is not "normal" operation and merely flushed out the fact that the product is missing a protective element on the primary side.

The (North American) fault condition not covered here is a transformer shorted (or partially) shorted primary or secondary winding. You don't know which two turns in a winding have shorted, it's not always end to end.

You'd have to short the secondary of the 120VAC transformer and see what the primary current rises to, and wait for the house to burn down. This is the danger: no overcurrent protection and a spread of fire under a single fault condition. The secondary winding will heat up. The magnet wire, bobbin, end covers are plastics and will burn. The product enclosure may join in. There may or may not be an arc fault at some point.

This is why a thermal fuse is inside smaller power transformers.
Bigger transformers don't have a thermal fuse because the safety standards require fusing at 167% (some 150%) of rated power.
This overload is enough that they don't get dangerously hot under a fault condition.

Let's go to the casino and bet on the mains breaker tripping, or bet on the product burning up.

[MT]

Soldering iron with augmented reality app??!! Management must be bored ore something"

[drussell]

You are missing a parameter, when the iron in the transformer is saturated the current is not just slightly higher, it is much higher.

That is a reasonable assumption, however it may or may not be true.  That depends on exactly when that particular transformer design saturates, etc.  Not all transformers will blow up instantly just because you connected them to 50 Hz instead of 60 Hz, or stuck twice the voltage across the primary, although most certainly some will be very unhappy in one or both of those cases. 

I do not have a 120VAC transformer around or I could do a curve of current vs. voltage.

Just taking any ol' transformer and showing a curve doesn't tell us anything about how this one behaves.  I have plenty of transformers around here that are intended to run on 120V but will work fine with a 240V input.  I have plenty more that would definitely go try to go thermonuclear. 

[HKJ]

You are missing a parameter, when the iron in the transformer is saturated the current is not just slightly higher, it is much higher.

That is a reasonable assumption, however it may or may not be true.  That depends on exactly when that particular transformer design saturates, etc.  Not all transformers will blow up instantly just because you connected them to 50 Hz instead of 60 Hz, or stuck twice the voltage across the primary, although most certainly some will be very unhappy in one or both of those cases. 

If it not designed to use the transformer iron fully it will, of course, not have serious problems.

I do
not have a 120VAC transformer around or I could do a curve of current vs. voltage.

Just taking any ol' transformer and showing a curve doesn't tell us anything about how this one behaves.  I have plenty of transformers around here that are intended to run on 120V but will work fine with a 240V input.  I have plenty more that would definitely go try to go thermonuclear. 

A Weller 120VAC transformer would be ideal, but any transformer that saturate the iron would give a good idea about what happens.
Anyway I hope somebody with a 120VAC Weller Iron can do a I/V curve for it. I expect it will go nuclear somewhere between 150VAC and 200VAC.

[timelessbeing]

the unit draws more than the breaker's rated current fow a while. That means a lot more time overheating, release smoke, and a lot more chances for it to set into fire.

Go ahead and stuff 2000W into a thin copper wire and see how long it lasts.

Which part would set fire? The copper wire or the steel core?

[Robaroni]

You can blow up stuff with 1W of power with the right conditions.

That would be a feat. Please explain.

Actually, you can choke on your muffin for 0W.

Perfect one liner.
 I'll exit here, it isn't going to get any better. We've beat this topic into complete submission.

Enjoy your Holiday everyone!

[timelessbeing]

I am just saying, a fuse is much better than an UL melting approved and specified procedure.

I don't know about you, but the lesson I learned here is: Don't plug devices intended for another country into your socket and you will be fine.

[timelessbeing]

it would still have saved the lab from fire.

What fire?