Auto-transformers are smaller than transformers because they use the same
windings for primary and secondary.
Iron sheet volume follows.
The reverse effect is that there's no isolation.



"Slurp" a écrit dans le message news:
...

"James Kelly" wrote in message
...
Hi,

I've recently moved to London in the UK and brought along my trusty
cooker. It states that it requires 120V @60/1235 watts. After some
research on the net it was apparant that transformers that provide
1000W
are at least the size of a shoebox and around $70-100. However, I later
came across a transformer sold by jWin which rates upto 1600W and is as
small as an average 100w transformer and costs about $10. You can see it
here - http://tinyurl.com/hra3r I called the shop selling them and
they
confirmed the specs.... am I wasting my time? You get what you pay for
right? Any help would be much appreciated.

James

On Fri, 31 Mar 2006 06:25:46 GMT, James Sweet wrote:


12,350W? That would draw more than 50A at 240V and produce over 42,000
BTU's, that's enough to heat a small house!

Just added up our (cheapo) cooker consumption:-
4 hobs 2000,1500,1500, 1000
grill 2850
oven 2400
if all on at once = 11,250 watts.


Geo

James Sweet wrote:
I wouldn't be so quick, the converters are simple and fairly robust.
They should be fused and will be perfectly safe to use.

The converter has no ground connection.
The oven has a large metal case that normally is grounded.
Running a oven with a large metal case without ground connection isnt
exactly what i think of being perfectly safe, especially not when the
line/ground voltage is twice of what it was made for.

Also, the oven states it has a automatical timer, which will not like
being run off such a converter and will likely fail.

In article ,
James Kelly wrote:
I've recently moved to London in the UK and brought along my trusty
cooker. It states that it requires 120V @60/1235 watts. After some
research on the net it was apparant that transformers that provide
1000W are at least the size of a shoebox and around $70-100. However, I
later came across a transformer sold by jWin which rates upto 1600W and
is as small as an average 100w transformer and costs about $10. You can
see it here - http://tinyurl.com/hra3r I called the shop selling them
and they confirmed the specs.... am I wasting my time? You get what you
pay for right? Any help would be much appreciated.

It doesn't have the standard UK plug for a start...

--
*Could it be that "I do " is the longest sentence? *

Dave Plowman London SW
To e-mail, change noise into sound.

"James Sweet" wrote in message
news:KX3Xf.11335$b07.3845@trnddc05...



What sort of things do you cook with a 1235 watt cooker???. That's nearly
a third of my electric kettle!!

You sure the rating is not 12350 watts which would be more reasonable. As
someone else hinted - get yourself a £29.99 800W 240V microwave, much
safer and more efficient!



12,350W? That would draw more than 50A at 240V and produce over 42,000
BTU's, that's enough to heat a small house!


1,235W on the other hand is perfectly reasonable for a cooker.

Really? My cooker is rated at 12500W, it has a 60A feed at 240V, quite
normal in the UK


That said, these converters are not transformers, they're essentially
triac light dimmers and will only work for purely resistive loads, such as
an electric cooker.

I did not say it wasn't.

On Fri, 31 Mar 2006 01:03:57 -0500, Michael Kennedy wrote:

Buy another identical cooker and wire the two in series.

hmm.. That sounds like a good idea.. you still have the 50/60 hz issue
with the timer but as long as that is dc it won't matter. I think you
might not even have any probs with it even if it is an ac timer.

Wiring them in series is very easy, but you will need to have 2 cookers
and run them both at the same time for everything to work.

- Mike

And either thermostat will turn them both off, and they definitely
won't voltage-share properly, so it will blow up the control electronics
in both.

IOW, a very very very bad idea.

Thanks,
Rich

"Rich Grise" wrote in message
news
On Fri, 31 Mar 2006 01:03:57 -0500, Michael Kennedy wrote:

Buy another identical cooker and wire the two in series.

hmm.. That sounds like a good idea.. you still have the 50/60 hz issue
with the timer but as long as that is dc it won't matter. I think you
might not even have any probs with it even if it is an ac timer.

Wiring them in series is very easy, but you will need to have 2 cookers
and run them both at the same time for everything to work.

- Mike

And either thermostat will turn them both off, and they definitely
won't voltage-share properly, so it will blow up the control electronics
in both.

IOW, a very very very bad idea.

Thanks,
Rich



You of all people should have spotted I was pulling the OPs leg!

"James Sweet" wrote in message
news:c%3Xf.11338$b07.7085@trnddc05...
James Kelly wrote:
Hi Dave,

Thanks for your reply. You sound like you know what you are talking
about, so I am going to take your advice and pack this thing up.... Some
other very helpfull folks have suggested the possibility of rewiring the
upper and lower elements in series to allow 220V or simply buying a 2nd
and wiring in series, but since my skills dont extend to this type of
work, I dont have a choice but to pack her away...sniff.....sniff.....
I'm overwhelmed by the support of this newsgroup though, people seem very
keen to help. Thanks again.



I wouldn't be so quick, the converters are simple and fairly robust. They
should be fused and will be perfectly safe to use.

On double insulated appliances maybe, definitely *not* on a cooker which is
no doubt meant to be earthed. The robustness of the unit is secondary.

Dave

"James Sweet" wrote in message
news:AZ3Xf.11337$b07.8640@trnddc05...
Greg Neill wrote:
"James Kelly" wrote in message
...

Yikes, ok so I bought it, its only $10 and I'll take the chance.... Any
danger though? Could this cause the convertor to melt/explode/catch
fire.....? Thanks again everyone.


I note that the unit doesn't appear to provide a ground
connection. This doesn't exactly give me warm fuzzies...




I've never seen any sort of portable cooker that had a ground connection
anyway, mine has a standard 2 prong cord.

Maybe so, but I'm willing to bet you are in North America, *not* the UK,
which is where the OP is based. Earthed metal bodied kitchen appliances like
bench top cookers are commonplace here.

Different country, continent for that matter- different regulations to
conform to.

dave

Really? My cooker is rated at 12500W, it has a 60A feed at 240V, quite
normal in the UK


Aren't we talking a small portable cooker? A fullsized kitchen range is
normally 50A in the US, but I thought we were discussing a single burner
hotplate type thing or toaster oven?

Dave D wrote:
"James Sweet" wrote in message
news:AZ3Xf.11337$b07.8640@trnddc05...

Greg Neill wrote:

"James Kelly" wrote in message
news:GtWdncUfIZAb27HZnZ2dnUVZ8tydnZ2d@giganews. com...


Yikes, ok so I bought it, its only $10 and I'll take the chance.... Any
danger though? Could this cause the convertor to melt/explode/catch
fire.....? Thanks again everyone.


I note that the unit doesn't appear to provide a ground
connection. This doesn't exactly give me warm fuzzies...




I've never seen any sort of portable cooker that had a ground connection
anyway, mine has a standard 2 prong cord.


Maybe so, but I'm willing to bet you are in North America, *not* the UK,
which is where the OP is based. Earthed metal bodied kitchen appliances like
bench top cookers are commonplace here.

Different country, continent for that matter- different regulations to
conform to.

dave



But isn't the cooker a NA model? Otherwise he wouldn't be needing a
converter in the first place.

On Fri, 31 Mar 2006 13:28:54 +0200, "frischmoutt"
Gave us:

Auto-transformers are smaller than transformers because they use the same
windings for primary and secondary.
Iron sheet volume follows.
The reverse effect is that there's no isolation.

The device he showed a pic of has NO transformer in it, you top
posting, Usenet retard.

"James Sweet" wrote in message
news:cCmXf.278$zk4.96@trnddc05...
Dave D wrote:
"James Sweet" wrote in message
news:AZ3Xf.11337$b07.8640@trnddc05...

Greg Neill wrote:

"James Kelly" wrote in message
news:GtWdncUfIZAb27HZnZ2dnUVZ8tydnZ2d@giganews. com...


Yikes, ok so I bought it, its only $10 and I'll take the chance....
Any
danger though? Could this cause the convertor to melt/explode/catch
fire.....? Thanks again everyone.


I note that the unit doesn't appear to provide a ground
connection. This doesn't exactly give me warm fuzzies...




I've never seen any sort of portable cooker that had a ground connection
anyway, mine has a standard 2 prong cord.


Maybe so, but I'm willing to bet you are in North America, *not* the UK,
which is where the OP is based. Earthed metal bodied kitchen appliances
like
bench top cookers are commonplace here.

Different country, continent for that matter- different regulations to
conform to.

dave



But isn't the cooker a NA model? Otherwise he wouldn't be needing a
converter in the first place.

Which of course leads to the obvious comment that it would be illegal to use
in UK anyway, just in case someone thinks that's worth considering. Coroners
do......

Ken

I.F. wrote:
You of all people should have spotted I was pulling the OPs leg!

Which leg? The hot or neutral?

Dave D wrote:

I wouldn't be so quick, the converters are simple and fairly robust.
They should be fused and will be perfectly safe to use.

On double insulated appliances maybe, definitely *not* on a cooker
which is no doubt meant to be earthed. The robustness of the unit is
secondary.
Dave

I have a similar gadget here, which also says 1600W, and I opened it up.
There is a big heatsink with a TO220 Triac(15A?) on it, a 18k 5W gate
resistor and a small cap which has no marking. There is also a bimetall
switch mounted on the heat sink with a heater where the load current runs
thru. Me think this is quite smart for an over-temperature and over-current
protection. I even used it to operate an American blender 50-s style, rated
for 800W. In the upper speed ranges it was working very well, but that was
all mechanical. If your oven has a small transformer in it for the
electronic timer it will probably function as well.
Another question is the safety. Without PE/earth the cooker is not
considered safe in England, which might be of concern if there is an
insurance event happening.
--
ciao Ban
Apricale, Italy

"James Sweet" wrote in message
news:cCmXf.278$zk4.96@trnddc05...

But isn't the cooker a NA model? Otherwise he wouldn't be needing a
converter in the first place.

Yes, precisely why triac based converter kludges on unearthed metal cased
appliances are a recipe for disaster, possibly even a case for compensation
claims should a third party be injured/killed. These converters worry me-
they imply to the lay purchaser that as long as the wattage and voltage
requirements are met, then it's safe to use. This is not necessarily the
case.

There is the matter of spacing between live PCB traces/wiring and chassis to
consider- 240V is far more likely than 120V to create a potentially fatal
situation if steam/moisture settles on live components and creates a path to
chassis.

Therefore, without examining the OP's equipment, and indeed the converter,
there's no way in hell I would advocate connecting either to a UK supply.


Dave

Hi James,
The ferromagnetic core has developed a lot it seems. Just try using a
simple load like heater. See if the cb breaker goes on or what.
Good Luck
Nitin

"Phil Allison" wrote in message
...

"Roger Hamlett"

Also, a 'cooker', that is rated at 1235W when running, will typically
draw many times this rating for a few seconds whenever the element
switches on.


** What bull**** !

Heating elements use wire with an essentially fixed resistance value.

Won't change by more than few percent from cold to hot.

Never heard of Ni-Chrome ???
Yes, heard of Ni-Chrome, and a _lot_ of modern equipment, does not use it
(cost)....
Many of the devices like the one being shown, use ceramic printed
elements, which have over 2:1 resistance change from cold to hot. Not as
large as things like Tungsten filament lamps, which typically have over
4:1, but still enough to need to be considered.

Best Wishes

On Sat, 1 Apr 2006 02:17:30 +0100, "Dave D" wrote:

Greg Neill wrote:
I've never seen any sort of portable cooker that had a ground connection
anyway, mine has a standard 2 prong cord.

Maybe so, but I'm willing to bet you are in North America, *not* the
UK, which is where the OP is based. Earthed metal bodied kitchen
appliances like bench top cookers are commonplace here.

That's only because there's still no one to pick up the challenge of
designing a heater-based appliance to withstand a 4.24kV(p) (@ both
prongs) insulation test (which is required for non grounded appliances
sold in the EU).
;-)

Different country, continent for that matter- different regulations
to conform to.

I can't believe that there are still end-users AND designers out there,
who are willing to find that out, the hard way :-P

"Roger Hamlett"


Also, a 'cooker', that is rated at 1235W when running, will typically
draw many times this rating for a few seconds whenever the element
switches on.


** What bull**** !

Heating elements use wire with an essentially fixed resistance value.

Won't change by more than few percent from cold to hot.

Never heard of Ni-Chrome ???


Yes, heard of Ni-Chrome, and a _lot_ of modern equipment, does not use it
(cost)....


** Many cheaper alternatives exist - all with low tempcos.


Many of the devices like the one being shown, use ceramic printed
elements, which have over 2:1 resistance change from cold to hot.


** More absolute BULL****.

The variation is only a few percent.



Not as large as things like Tungsten filament lamps, which typically have
over 4:1,


** Tungsten lamps vary by a ratio of 10:1 or more.

You are just plucking numbers out of you fat bum.





.......... Phil

On 31 Mar 2006 23:22:53 -0800, "Nitin" Gave us:

Hi James,
The ferromagnetic core has developed a lot it seems. Just try using a
simple load like heater. See if the cb breaker goes on or what.
Good Luck
Nitin


Actually, he should buy a heater for that locale, and take the
correct heater for the locale he is to be in, depending on where he
decides to go. Problem solved.

On 31 Mar 2006 23:22:53 -0800, "Nitin" wrote:

Hi James,
The ferromagnetic core has developed a lot it seems. Just try using a
simple load like heater. See if the cb breaker goes on or what.
Good Luck
Nitin

---
Not only do you not know what you're talking about, you ought to
learn to post properly.

Since you're posting from Google groups, maybe you ought to read
what they have to say about it. From:

http://groups.google.com/support/bin...2348&topic=250

"Summarize what you're following up.

When you click "Reply" under "show options" to follow up an existing
article, Google Groups includes the full article in quotes, with the
cursor at the top of the article. Tempting though it is to just
start typing your message, please STOP and do two things first.
Look at the quoted text and remove parts that are irrelevant.
Then, go to the BOTTOM of the article and start typing there.
Doing this makes it much easier for your readers to get through your
post. They'll have a reminder of the relevant text before your
comment, but won't have to re-read the entire article.
And if your reply appears on a site before the original article
does,
they'll get the gist of what you're talking about."


--
John Fields
Professional Circuit Designer

"Phil Allison" wrote in message
...

"Roger Hamlett"


Also, a 'cooker', that is rated at 1235W when running, will typically
draw many times this rating for a few seconds whenever the element
switches on.


** What bull**** !

Heating elements use wire with an essentially fixed resistance value.

Won't change by more than few percent from cold to hot.

Never heard of Ni-Chrome ???


Yes, heard of Ni-Chrome, and a _lot_ of modern equipment, does not use
it (cost)....


** Many cheaper alternatives exist - all with low tempcos.


Many of the devices like the one being shown, use ceramic printed
elements, which have over 2:1 resistance change from cold to hot.


** More absolute BULL****.

The variation is only a few percent.



Not as large as things like Tungsten filament lamps, which typically
have over 4:1,


** Tungsten lamps vary by a ratio of 10:1 or more.

You are just plucking numbers out of you fat bum.
I suggest you take your medicine, and stop being rude.
I said 'Tungsten filament lamps', as are used in devices like this for
heating, _not_ for light bulbs. Given that this was a discussion about
heating units, I would hope that anybody using even a few of their brain
cells would understand this. In these applications, the filaments are
typically run under 1000C, and have hot/cold resistances in the order of
4/5:1. 10:1, is the figure for a light heating to around 2200C.
My figures are not 'plucked', but are based upon over 100 different
kitchen applicances, that were tested by a company who I sometimes work
for, as part of designing the electronics to feed a mains socket, from a
DC inverter, in a caravan. They took peak current readings (this working
off normal rated mains, so the inverter was not causing the difference),
with a recording meter, for just about every kitchen appliance (waffle
irons, kettles etc.), that they could borrow. We were suprised to find
that most modern units of this sort (grilling units etc.), had higher
inrush currents than we expected. Over 30%, drew nearly twice the current
on 'switch on', that they drew when running. Most drew between this, and
4* the current expected. Just two, drew slightly more than this (peaking
at 6.2*). The commonest heating elements, on dismantling a few units, were
effectively PCB's printed on a ceramic substrate, while the units
exhibiting the highest surge, had glass lamps running between dull red,
through to a bright red heat. Countries of origin, ranged from the UK,
Italy, and Japan, yet none (except one old kettle), behaved as a normal
ni-chrome heating element would behave.

Best Wishes

James Kelly wrote:
Hi,

I've recently moved to London in the UK and brought along my trusty cooker.
It states that it requires 120V @60/1235 watts. After some research on the
net it was apparant that transformers that provide 1000W are at least the
size of a shoebox and around $70-100. However, I later came across a
transformer sold by jWin which rates upto 1600W and is as small as an
average 100w transformer and costs about $10. You can see it here -
http://tinyurl.com/hra3r I called the shop selling them and they confirmed
the specs.... am I wasting my time? You get what you pay for right? Any help
would be much appreciated.

James

It doesn't change the voltage, just the connector. ie to the US style
plug.

wrote:
It doesn't change the voltage, just the connector. ie to the US style
plug.

Really?
"Converts 220/240V To U.S. Standard 110/120V"

That's the normal way to post on most company e-mailers (id; Lotus Notes).
I keep this habit;
Opinions are shared on the topic. I agree with myself.

Thanks for the feedback and the politeness dear Sir.


"Roy L. Fuchs" a écrit dans le message
news: ...
On Fri, 31 Mar 2006 13:28:54 +0200, "frischmoutt"
Gave us:

Auto-transformers are smaller than transformers because they use the same
windings for primary and secondary.
Iron sheet volume follows.
The reverse effect is that there's no isolation.

The device he showed a pic of has NO transformer in it, you top
posting, Usenet retard.

On Sun, 2 Apr 2006 22:24:43 +0200, "frischmoutt"
wrote:

That's the normal way to post on most company e-mailers (id; Lotus Notes).
I keep this habit;

---
You should be _wearing_ a habit, you pretentious little ****.
---

Opinions are shared on the topic. I agree with myself.

---
You're a myopic ass who's living in a fantasy world.

Wanna play on USENET and not get your ears pinned back?

Learn the rules.

1. Don't top post.
2. Use context.

Even for you, how hard can that be to learn?
---

Thanks for the feedback and the politeness dear Sir.

---
Stuff the sarcasm.

I notice that you've conveniently left out any reference to the fact
that Fuchs nailed you because you were too ****ing stupid to realize
that the device was _not_ a transformer, and instead of
acknowledging your error have now decided to go the route of
defending your post based on email posting conventions in your
company.

This is not your company's email, you ****ing twit, this is USENET,
where we'll rip your heart out in an instant if you **** with us.


--
John Fields
Professional Circuit Designer

In article , Phil Allison wrote:

"Roger Hamlett"

Also, a 'cooker', that is rated at 1235W when running, will typically draw
many times this rating for a few seconds whenever the element switches on.


** What bull**** !

Heating elements use wire with an essentially fixed resistance value.

Won't change by more than few percent from cold to hot.

Never heard of Ni-Chrome ???

I had nichrome have cold resistance half its hot resistance. Less of a
change than most other metals - most metals have resistance about
proportional to absolute temperature. Tungsten has resistance varying
even more drastically with temperature than proportional to absolute
temperature.

- Don Klipstein )

"Roger Hamlett" wrote:

** Also, a 'cooker', that is rated at 1235W when running, will typically
draw many times this rating for a few seconds whenever the element
switches on. **



** What bull**** !

Heating elements use wire with an essentially fixed resistance value.

Won't change by more than few percent from cold to hot.

Never heard of Ni-Chrome ???


Yes, heard of Ni-Chrome, and a _lot_ of modern equipment, does not use
it (cost)....


** Many cheaper alternatives exist - all with low tempcos.


Many of the devices like the one being shown, use ceramic printed
elements, which have over 2:1 resistance change from cold to hot.


** More absolute BULL****.

The variation is only a few percent.


Not as large as things like Tungsten filament lamps, which typically
have over 4:1,


** Tungsten lamps vary by a ratio of 10:1 or more.

You are just plucking numbers out of you fat bum.

I suggest you take your medicine, and stop being rude.


** You need to take a dose of rat bait and stop posting utter bull**** on a
public forum.


I said 'Tungsten filament lamps', as are used in devices like this for
heating, _not_ for light bulbs.


** Shame you did not **post** any such damn thing.

My comment was totally correct and stands.


BTW:

I tested a modern (Chinese made) 2400 watt electric kettle.

Current draw started at 9.4 amps slowly falling to 9.2 amps.

Similarly for an modern, 800 watt toaster, 3.3amps falling to 3.2 amps.

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


What you claimed above about a 1250 watt heating element is just pain WRONG.

The initial current draw is not "many times" that indicated by the the
name plate wattage rating.

Domestic circuit breakers will not allow such extended period overloads.





........ Phil

or you can open the cooker and put the resistors in series to obtain
240v ..?

frischmoutt wrote:
That's the normal way to post on most company e-mailers (id; Lotus
Notes). I keep this habit;

Then please post further comments on your company e-mail system, not on
this Usenet newsgroup.

OK call mom and complain

"John Fields" a écrit dans le message news:
...
On Sun, 2 Apr 2006 22:24:43 +0200, "frischmoutt"
wrote:

That's the normal way to post on most company e-mailers (id; Lotus
Notes).
I keep this habit;

---
You should be _wearing_ a habit, you pretentious little ****.
---

Opinions are shared on the topic. I agree with myself.

---
You're a myopic ass who's living in a fantasy world.

Wanna play on USENET and not get your ears pinned back?

Learn the rules.

1. Don't top post.
2. Use context.

Even for you, how hard can that be to learn?
---

Thanks for the feedback and the politeness dear Sir.

---
Stuff the sarcasm.

I notice that you've conveniently left out any reference to the fact
that Fuchs nailed you because you were too ****ing stupid to realize
that the device was _not_ a transformer, and instead of
acknowledging your error have now decided to go the route of
defending your post based on email posting conventions in your
company.

This is not your company's email, you ****ing twit, this is USENET,
where we'll rip your heart out in an instant if you **** with us.


--
John Fields
Professional Circuit Designer

On Mon, 3 Apr 2006 22:12:03 +0200, "frischmoutt"
wrote:

OK call mom and complain

---
Why bother? Trash like you are your own worst enemies and you'll
blow up soon enough if left alone.

--
John Fields
Professional Circuit Designer

Hi James,

As one person mentioned, if you badly want to use your pizza oven, buy
a genuine transformer with plenty of copper and iron in it. It's the
proper solution to the problem, will produce a nice waveform and won't
run the risk of overheating if you select one with an appropriate
continuous power rating. Such transformers are frequently used on
building sites in the UK. Usually they have a yellow fibre glass case,
but sometimes they're grey metal if intended for permanent
installation. I have one which I use to power a Hougen magnetic drill,
and they perhaps aren't as expensive as you might think. Figure about
£30 plus delivery for a used transformer in good condition. If you
search hard you might get one for less. Something like this should
satisfy your needs:

http://cgi.ebay.co.uk/ws/eBayISAPI.d...tem=7604254309

Best wishes,

Chris