is it possible? 1600W step-down transformer so tiny!

[Ban]

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.

 

[Dave D]

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

 

[Nitin]

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

 

[Roger Hamlett]

"Roger Hamlett"


** What bullshit !

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

 

[ELAL]

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

 

[Phil Allison]

"Roger Hamlett"

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 BULLSHIT.

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

 

[Roy L. Fuchs]

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.

 

[John Fields]

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/answer.py?answer=12348&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."

 

[Roger Hamlett]

"Roger Hamlett"



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




** More absolute BULLSHIT.

The variation is only a few percent.





** 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

 

[[email protected]]

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.

 

[Travis Jordan]

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"

 

[frischmoutt]

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.

 

[John Fields]

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 twat.
---

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 fucking 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 fucking twit, this is USENET,
where we'll rip your heart out in an instant if you **** with us.

 

[Mochuelo]

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


---
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?
---


---
Stuff the sarcasm.

I notice that you've conveniently left out any reference to the fact
that Fuchs nailed you because you were too fucking 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 fucking twit, this is USENET,
where we'll rip your heart out in an instant if you **** with us.

Neither making a mistake (if that was the case) nor top posting in
usenet makes anyone a "retarded" person, a "pretentious little twat,"
a "myopic ass," a "fucking stupid" or a "fucking twit". "Roy L. Fuchs"
and "John Fields," you guys make me feel I'm going to vomit.

 

[Don Klipstein]

"Roger Hamlett"


** What bullshit !

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 ([email protected])

 

[Phil Allison]

"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. **

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

** You need to take a dose of rat bait and stop posting utter bullshit 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

 

[inty's world]

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

 

[John Fields]

Ok, I may end up believing that you have access to 60 A @ 240 V. But I
find it... surprising... that you guys use 12.5 kW cookers. That's a
hell of power. And ok, even if that was the case, I could never call
that "reasonable."

---
Get over yourself.

If that's what his cooker needs and the mains can supply it, it's
perfectly reasonable and whether you'd call it that or not is
totally immaterial.

 

[John Fields]

Neither making a mistake (if that was the case) nor top posting in
usenet makes anyone a "retarded" person, a "pretentious little twat,"
a "myopic ass," a "fucking stupid" or a "fucking twit". "Roy L. Fuchs"
and "John Fields," you guys make me feel I'm going to vomit.

---
Now _there's_ a visual, watching a puke puke!

BTW, it's not: "a "fucking stupid"", its just: ""fucking stupid"",

I guess English isn't your first language, huh?

You also seem to have had some trouble figuring out that 240V * 60A
is more than enough to supply a 12.5kW cooker with all the power it
needs.

What is it you do, anyweay?

 

[Mochuelo]

---
Now _there's_ a visual, watching a puke puke!

BTW, it's not: "a "fucking stupid"", its just: ""fucking stupid"",

I guess English isn't your first language, huh?

You also seem to have had some trouble figuring out that 240V * 60A
is more than enough to supply a 12.5kW cooker with all the power it
needs.

What is it you do, anyweay?

Stop being rude, and learn how to write "anyway" in your first and
only language, which turns out to be my third one. Learn also to put
the commas inside the quotation marks, and to leave a space between
the numerical value and unit symbol
(http://physics.nist.gov/cuu/Units/checklist.html #15). If you can't
use your own language, don't be so pretentious. Of course I can
multiply, and what I do is none of your business. This is my last
reply to you, John Fields.