Author Topic: EEVblog #1160 - Weller Responds  (Read 48639 times)

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Online EEVblog

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Re: EEVblog #1160 - Weller Responds
« Reply #825 on: January 06, 2019, 11:26:51 am »
DJ states he has a 16 amp RCBO breaker (single or dual space combined RCD/GFCI and MCB)

Correction, it's a 20A breaker, with 30mA RCD.
 

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Re: EEVblog #1160 - Weller Responds
« Reply #826 on: January 06, 2019, 11:32:04 am »
DJ states he has a 16 amp RCBO breaker (single or dual space combined RCD/GFCI and MCB)
e.g. If a 140 amp transformer welder pulling constant and intermittent 15 to 35 amps current at 240v
at near and full short circuit conditions on the transformer secondary (during actual non stop arc welding with 3.2 or 4mm electrodes)
it will do it tough to pop the 16 amp breaker but may/will eventually...

this is assuming the welder and leads are in good shape with direct plug in connection to a standard GPO wall socket
(i.e. no amateurish backyarder flimsy 10 amp extension cord malarky) 

So what chance has a sizzling lil Weller trannie got to pop DJs breaker ?  > PowerBall win chances ?

At best if it's plugged in to a 4 or 6 way power strip board with a thermal breaker/Reset thingie, the ones with the small black or red switch usually near the cord entry,
it may heat up around the 8 to 12 amp range (depending on the breaker design/curve) and trip the power board.

More clarification:
It was plugged into two power boards in series, each of which has it's own (presumably 10A as that's the total rating) breaker. Plus the main switch board 20A breaker.
The power board breakers were not tripped.
So absolutely no way it tripped the 20A mains breaker without tripping the others, it was most certainly the 30mA RCD that tripped.
 

Offline timelessbeing

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Re: EEVblog #1160 - Weller Responds
« Reply #827 on: January 06, 2019, 12:17:37 pm »
You were arguing that the transformer is unsafe.

No, I was not.

you cannot guarantee the safety of a transformer that was smoking it's enamel.
Why not?

Because the enamel melts and the turns short out,
and this likely happens in a progressive accelerated fashion, effectively feeding on itself in a thermal runaway of sorts.
 

Offline timelessbeing

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Re: EEVblog #1160 - Weller Responds
« Reply #828 on: January 06, 2019, 12:25:20 pm »
@ timelessbeing, there's no feeling threatened or personal vibe here mate  :-//

Thank you. Likewise, and I do appreciate your sense of humour.

Some are getting a bit defensive, and this guy wants me to die.

Dave, dont worry. Darwinism will take good care of these people.  >:D
 

Offline timelessbeing

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Re: EEVblog #1160 - Weller Responds
« Reply #829 on: January 06, 2019, 12:31:22 pm »
pulling the plug caused the RCD part to trip
Please pardon my ignorance, but how does that work?
 

Offline Wolfgang

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Re: EEVblog #1160 - Weller Responds
« Reply #830 on: January 06, 2019, 12:32:15 pm »
@ timelessbeing, there's no feeling threatened or personal vibe here mate  :-//

Thank you. Likewise, and I do appreciate your sense of humour.

Some are getting a bit defensive, and this guy wants me to die.

Dave, dont worry. Darwinism will take good care of these people.  >:D

Poor chap. Now that they run out of arguments, they also run out of humour. Two smileys this time  :) :) I was trying to fight for a safer world, and now look at this  :palm:
 

Online tautech

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Re: EEVblog #1160 - Weller Responds
« Reply #831 on: January 06, 2019, 12:34:17 pm »
@ timelessbeing, there's no feeling threatened or personal vibe here mate  :-//

Thank you. Likewise, and I do appreciate your sense of humour.

Some are getting a bit defensive, and this guy wants me to die.

Dave, dont worry. Darwinism will take good care of these people.  >:D
:o
Can you not see the potential for primary to secondary isolation failure and unfused mains into the iron element ?
Then....  :o
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Offline floobydust

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Re: EEVblog #1160 - Weller Responds
« Reply #832 on: January 06, 2019, 12:42:36 pm »
If you look at the soldering station's PCB's grounding, it's um not so great.

My experience is certifiers will pass full current 15A (in North America) through ground for an hour to ensure the safety ground would not fail. This checks things like via's, thermal reliefs, PCB traces etc. do not open-circuit. Now take a look at the Weller PCB... see if you can spot it.

If the transformer was allowed to continue to burn up, the bobbin can melt inside and cause mains to bridge over to the secondary winding. The melting bobbin can also bridge primary to the core. It is all part of the transformer certification checks.
 

Offline timelessbeing

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Re: EEVblog #1160 - Weller Responds
« Reply #833 on: January 06, 2019, 12:49:35 pm »
Can you not see the potential for primary to secondary isolation failure and unfused mains into the iron element ?
Even if the potential could actually be quantified, there is protection after the secondary.

I doubt that the wire would have the energy or time required to melt through the bobbin and contact the core, but even if it did, it's contained in the enclosure.
 

Offline Electro Detective

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Re: EEVblog #1160 - Weller Responds
« Reply #834 on: January 06, 2019, 12:56:00 pm »
pulling the plug caused the RCD part to trip

Please pardon my ignorance, but how does that work?


It's a fair question, so here goes...  :-// 

When he pulled the plug, chances are that both the active and neutral pins did not come out at the same time,
so the RCD sensed a 30ma+  imbalance to earth/ground/third pin with the smouldering load pulling amps, and popped

If the MCB section had popped, there would have been a spark and the zapped plug/socket eminating a slight scent of...brimstone ?  >:D

 

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Re: EEVblog #1160 - Weller Responds
« Reply #835 on: January 06, 2019, 01:16:01 pm »
pulling the plug caused the RCD part to trip

Please pardon my ignorance, but how does that work?


It's a fair question, so here goes...  :-// 

When he pulled the plug, chances are that both the active and neutral pins did not come out at the same time,
so the RCD sensed a 30ma+  imbalance to earth/ground/third pin with the smouldering load pulling amps, and popped

If the MCB section had popped, there would have been a spark and the zapped plug/socket eminating a slight scent of...brimstone ?  >:D

There could also have been significant leakage the earth already from the melting enamel and smoke etc, and didn't take take much else to trip it. RCD's can trip all the time based on all sorts of factors like inductive kickback from suddenly disconnected loads and other influences.
 
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Offline timelessbeing

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Re: EEVblog #1160 - Weller Responds
« Reply #836 on: January 06, 2019, 03:12:57 pm »
I see. The transformer was highly energized, so the inductive kickback would have been beyond normal too. It likely arced to ground somewhere.
 

Offline LapTop006

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Re: EEVblog #1160 - Weller Responds
« Reply #837 on: January 06, 2019, 03:49:43 pm »
There could also have been significant leakage the earth already from the melting enamel and smoke etc, and didn't take take much else to trip it. RCD's can trip all the time based on all sorts of factors like inductive kickback from suddenly disconnected loads and other influences.

Plus any other devices on the circuit.
 

Offline nharrer

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Re: EEVblog #1160 - Weller Responds
« Reply #838 on: January 12, 2019, 06:30:07 am »
Remember the days when the fuse was on the front panel:

Oh boy. I opened my station to check if it has a fuse. Only to find out that it has that front fuse. I looked at it so many times I didn't notice it anymore  :palm:








 
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Offline Mr. Scram

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Re: EEVblog #1160 - Weller Responds
« Reply #839 on: January 12, 2019, 06:49:57 am »
The one making the claim here is Weller.
They have asserted by their own actions and lack of technical response to this issue that a fuse is not worthwhile in a couple of their low end products, but is presumably worthwhile in all their other products.
Weller need to answer this, not the community.
So far Weller seems to be right, as no real danger has been properly been quantified. I don't really understand how people can be so adamant about Weller being in the wrong without coming up with anything tangible.
« Last Edit: January 12, 2019, 06:59:08 am by Mr. Scram »
 

Offline floobydust

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Re: EEVblog #1160 - Weller Responds
« Reply #840 on: January 12, 2019, 07:45:54 am »
Let us consider the WE1010NA secondary-side fusing. Three protective devices in series  :clap:

I can't see the PTC ever tripping, it's rated 14A and the quicker of the two other fuses will trip first.
We all know a shorted transformer secondary winding here would result in a BBQ.

During product certifications, one fault can (generally) be injected to the product, an open or short here or there as the safety standard dictates or the certifier chooses, to see if an unsafe condition results.

The only reason I know of that would justify the triple-stupid string of fuses, is to thwart a short at "the output of the transformer" test defined as after the PTC+fuse, a technicality as they "belong" to the transformer assembly, they are part of the transformer. So short things after them. It seems to be a CYA for the lack of primary fusing.

The transformer's external fuse has no part number, a Gerrman ELU/Siba item with only UL approval.
Oddly it is varnish-dipped along with the transformer and PTC. Varnish can get into the fuse housing during the Vacuum Pressure Impregnation and corrupt its operation. Regulatory does not permit this- unless a fuse is declared air-tight, which is extremely rare.

So this is a second Weller mess on this product.
« Last Edit: January 12, 2019, 07:47:47 am by floobydust »
 
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Offline Electro Detective

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Re: EEVblog #1160 - Weller Responds
« Reply #841 on: January 12, 2019, 09:55:19 am »
I'm convinced (in MOST cases) they no longer even test these heat producing devices under real world conditions,
they just buy up the parts according to design drafts and wack them in (or wrist burn OHL assemblers to do it cheaper than cheap),
without even a quick pre test of the safety components before fitting,
LOL even if they are 'Never Trip' values to begin with  ::)

You would think the bosses and staff might take some prototype units home for some weekend project soldering,
put them through the paces and report back before release,
as well as sneak in a SUGGESTION to add in cheap fuses as CHEAP INSURANCE!  :phew:

It's dumbass at best and or manufacturer foot shooting  :palm:


FWIW rumour suggests a LOT of these companies are now  ~owned~  by electronics challenged CLUELESS shyster investment groups
that either don't employ and or suppress proper EE SAFETY recommendations,
perhaps fudge the UL thing,

then release their corpotrolls on the inernet to do damage control dirty work   >:D >:D

That used to sort of work back in 2000 AD, but it's like 2019 now and people are a bit more internet savvy,
well, not by much, just a bit more than not at all...  :D

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

So folks, do ya reckon the corpotrolls will throw in the dirty towel and report back to the bosses to fit some fusing in the suckers
before dwindling reputation and sales begin to go seriously south?  :popcorn:



 

Offline coppercone2

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Re: EEVblog #1160 - Weller Responds
« Reply #842 on: January 12, 2019, 11:07:00 am »
i wonder if you can put some kind of mechanical diode/integrator to work on thermal fuse expansion so that if it expands a few times times due to a thermal oscillation condition it breaks a switch.

It always bugged me that its maybe possible for a damaged device to oscillate like that with a thermal fuse.

Think of one of those dishwasher expansion thingies connected to a gear train.
« Last Edit: January 12, 2019, 11:09:05 am by coppercone2 »
 

Offline floobydust

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Re: EEVblog #1160 - Weller Responds
« Reply #843 on: January 12, 2019, 12:36:10 pm »
Thermal links do fatigue fail, they are a soft alloy and experience inrush currents. Unless you mean cycling a resettable one?

A thermal fuse here would be rated below the magnet wire polyurethane and bobbin plastic limit of around 125°C.
Salvation pic from: https://www.eevblog.com/forum/beginners/is-a-thermal-fuse-a-current-fuse-as-well/msg1276728/#msg1276728
 

Offline graybeard

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Re: EEVblog #1160 - Weller Responds
« Reply #844 on: February 17, 2019, 06:19:52 am »
Here are some photos from inside one of my Weller WTCP soldering stations.  As the schematic above shows there is no fuse in the primary of the transformer.  The transformer is also constructed in a manner I have not seen before with the majority of the wingdings exposed.





 

Online Ian.M

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Re: EEVblog #1160 - Weller Responds
« Reply #845 on: February 17, 2019, 06:42:23 am »
@graybeard:
Quote
Forbidden

You don't have permission to access /eevblog/WTCP_TC202-1.JPG on this server.

Apache/2.2.16 (Debian) Server at diver.net Port 80
>:(
 

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Re: EEVblog #1160 - Weller Responds
« Reply #846 on: February 17, 2019, 06:46:45 am »
@graybeard:
Quote
Forbidden

You don't have permission to access /eevblog/WTCP_TC202-1.JPG on this server.

Apache/2.2.16 (Debian) Server at diver.net Port 80
>:(
Images load fine on W10 and a Chrome browser.  :-//
Avid Rabid Hobbyist
 

Offline madires

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Re: EEVblog #1160 - Weller Responds
« Reply #847 on: February 17, 2019, 06:47:08 am »
Is that an used soldering station or have you bought it brand new?
 

Offline graybeard

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Re: EEVblog #1160 - Weller Responds
« Reply #848 on: February 17, 2019, 09:43:08 am »
Is that an used soldering station or have you bought it brand new?

I got it used 35 years ago.  It spent 30 years approximately 200 yards from the Pacific Ocean.  I have two of them and they still both work well.
« Last Edit: February 17, 2019, 09:46:34 am by graybeard »
 

Offline floobydust

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Re: EEVblog #1160 - Weller Responds
« Reply #849 on: February 17, 2019, 09:44:33 am »
Here are some photos from inside one of my Weller WTCP soldering stations.  As the schematic above shows there is no fuse in the primary of the transformer.  The transformer is also constructed in a manner I have not seen before with the majority of the windings exposed.

That is an antique station. No primary fuse (North America) was from a day of older electrical safety standards. UL 336B is long gone. My guess the primary-side fuse showed up around 1990 in Weller stations.

Inside is one of the solenoid-style power transformers used by Weller in their soldering guns and older stations.
It has a ton of leakage flux, they used to make CRT monitors/TV's wiggle in the shop and add hum to any nearby breadboarding.
 


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