Cooling of overloaded transformer

Afraid it won't work. Before the core has a chance to heat up one of the windings will likely start to smoke. Or if the transformer has one it may irreversibly blow an internal thermofuse. It might even work with just one round of toasts but you know how it is. Guests come over and then "Oh, let's prepare 10 slices of toast".

There could also be some "discussion" with the adjuster of your home insurance about replacing the kitchen furniture after it has gone wrong :-)

What I have done in Europe, but that was not legit per code: I needed

Thanks Joerg

I suspected the same, better not to take any risk at all

Normal transformers are heat limited, and if the 600W was rated at 60 degrees ambient and I will be running it low temp

But secondary winding losses is on the square of current, so would probably not be wise

Of course, have overrun them hugely. Don't. You don't need a transformer, you need a dropper.

NT

Copper loss goes as current squared, so you can't overload it much.

(1300/600)^2 is probably too much, even with extra cooling.

How much does a good 240V toaster cost where you are?

I like this one

but a 240V toaster can go to 1800 watts, which would sure save time.

you can heatsink it a lot too. But don't. Life expectancy goes down a lot, the interior still gets hot.

Memory is a bit fuzzy but I think I once pushed a mains transformer to about 3x output current long ago. It's terrible for regulation & MTTF, I wouldn't consider doing it today.

I once had a 3.5kW one. I think you can still get 3.1kW.

NT

I do most house wiring live, because getting bit by 120V isn't a big deal. 240 makes a lot of sense - less current, more power - but I bet it hurts a lot more.

After 1 bite people are usually scared senseless.

NT

OK, I'm not suggesting this, but since it is a resistive load, Could you put a non-polarized 260uv cap in series with the toaster. The capacitive reactance would be equal to the resistance of the toaster, or 11.3 ohms. (think speaker crossover caps,it may not be cost effective) I would break this up into 13- 20uf capacitors to reduce the current in each down to about 1 amp. Also the voltage rating, I think it has to be at least 400V, but I'm not sure how to calculate that. (hope it's 200V, they are available) I once used this to drop about 40V down before a bridge for a 5V regulator, where I didn't want anymore heat. I just substituted until I had a reasonable input voltage. Harder to calculate because of gulps of current at the peaks. I would like some comments about calculating this for the resistive toaster. If you think it is a stupid idea, explain why. Explain the pitfalls. Mikek

Yes, but I have been unable to find one

I could do one myself, but that's a project the better half won't wait for

AC->DC->Inverter stage

My wife likes the kitchen aid stuff, so we have 115V mixer, toster, longtime cooker, etc

Kitchen Aid is 50% price in USA. Amazon won't ship to denmark, so I pick it up when I am there on business. One time I had a big mixer with me, and I was pulled aside, they thought it was a bomb :-)

Cheers

Klaus

Capacitive droppers are good, but in this case the load is all over the place (low resistance when cold, higher when warm, different power levels etc)

But good point about thinking outside the box :-)

Cheers

Klaus

That's your answer: just buy a less powerful toaster.

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Not me. I can barely sense it. One of the benefits of having very dry skin. One of the dis-benefits of same, however, is getting constantly zapped by static in the winter months.

How much lower is the R when cold? It would just heat up a little faster, a little more current through the caps for a short time, nothing unusual. Does your toaster actually have different power levels, or just different toasting times. My toaster is early 20th century technology.

The "bite" goes up with the cube of the voltage. Or so it seams.

Happy Easter all.

Mine has a fixed 1200W power, with a timer based on a CD4541. The timer works nicely but the mains voltage varies widely and this results in varying degrees of toast.

There may be a much simpler solution. Toasters have multiple heating elements, so why not check whether they are all in series or in a series/parallel arrangement. If they are in series/parallel, then converting to series connection might allow correct operation at 230V. Manufacturers might make the elements operate at 115V each and adjust the internal wiring to suit different markets.

It may not work out, but it would be worth a look inside.

The solenoid in the "pop-up" mechanism might be a bit harder to deal with.

John

We don't have pole pigs, our local distribution is 3 phase at 240v L-N, so accommodating 120-0-120 within that is not really workable. 120-0-120 also adds issues & costs since N is then live as well as L. Incoming fusing was double pole in the 1930s, and caused well established safety hazards, it's long since banned.

Building sites used to be required to use 55-0-55, that has now been droppe d in favour of 240v & a RCD/GFCI.

NT