Slow microwave ovens

[William Gothberg]

1200W isn't much more than the 900W most are.

[William Gothberg]

Only with a small number of things, where you'd just select half power. For example I often put in a large bowl of pasta or veg full of cold water, not covered. That water would easily handle 2kW. ONly packaged food in cheap plastic containers is a problem, and those will already melt in my 800W microwave. I always empty them into a real bowl first.

13A 240V in the UK, no problem to get 3kW. The USA has those too.

My socket circuit is 30A. More modern houses are 32A. Larger houses have two 32A circuits. At 240V, so enough for about 7kW.

[William Gothberg]

Why is it called an invertor? I thought an invertor was a device to increase the voltage - like running 240V devices off a 12V car battery.

And why on earth would you not want to cook on full power? I've never had a reason to lower the power from the maximum of 800W. I want the meal as soon as possible!

[Arthur Conan Doyle]

The idea is not to cook the food as its defrosting. Full power is fine if you want the end item hot. It's not good if you want something room tempurature or slightly cooler to use as a part of preparation of something else.

[Arthur Conan Doyle]

In the US 240v sockets are typically found in the kitchen for use by an electric range, or in a dedicated laundry room for use by an electric dryer. Sometimes they can be found in a garage. The interior outlets are typicaly located behind the appliance - in effect dedicated for that appliance and not intended for general use.

[Arthur Conan Doyle]

Typical microwaves use fixed AC power to drive the magnetron. Inverter driven magnetrons use DC power, which can be variable.

[William Gothberg]

Then I just use less cooking time. Full power will defrost to room temperature much faster than that pointless defrost mode. And if you're about to say it won't be even, so what? If it's for part of preparation of something else, it has plenty time to even out.

[William Gothberg]

I'd find that severely limiting. 2kW hoover, 2kW kettle, breadmaker, toaster, etc, etc.

[rbowman]

I worked for a company around 1970 that developed a few high power microwaves that were placed in area restaurants. The idea, now completely familiar, was the restaurant could prepare quantities of food, freeze them, and thaw on demand. Other companies had similar industrial ovens.

The core business of the company was industrial plastics preheaters which functioned at around 100 MHz rather than microwave frequencies. They completely missed the consumer microwave market that was to grow in the later '70s.

We always had a couple of the smaller preheaters hanging around engineering. They did wonders for stale donuts. Even the factory workers in the molding plants caught on. 'I bet if that thing can heat a phenolic biscuit to 300 degrees it would work on my sandwich.' We didn't explicitly mention it when installing new equipment other than vague cautions about not putting aluminum foil in the cavity. The larger models were 15 KW and could generate some Tesla quality fireworks.

As the various RF technologies like heat sealers made it to the workplace a whole folklore grew up. Working around them could either make you sterile or incredibly fertile, take your pick.

The technology has been around for over 50 years. What you find at Tesco is what sells.

[William Gothberg]

1kW hoovers are shit, especially if you have pets or carpets.

[William Gothberg]

So they rectify the AC, then boost the DC voltage as required by the user setting?

But even without an invertor, surely you could have a few tappings on a transformer to change the AC voltage to the magnetron? It's not like you need infinite control, just 3 or 4 would do.

[William Gothberg]

I've watched countless Youtube videos of people abusing microwaves. The funniest one was a teenager who thought it would be a good idea to microwave one of those chemical lights - the ones you shake and they glow green. It exploded and got him in the eyes, followed by his father yelling "I told you not to do that!". I fell off my chair laughing.

I'm surprised people aren't going for "super fast microwave, cook your meal in 5 minutes" varieties.

[William Gothberg]

Microwaving something in a cheap shit plastic container is insane. I always cook or eat things in a real pot bowl. Plastic melts!

[William Gothberg]

I don't seem to have that problem, full power defrosts things evenly enough. Some bits are probably a bit hotter than others, but it's evened out by the time I eat it.

[Dean Hoffman]

Pretty much the same reason one doesn't always turn a conventional oven up to broil. 350º F. is a pretty common setting if my memory is working. T4 has a good example. It comes down to lack of demand.

[Andrew Gabriel]

To run a 5kV magnetron from 240V.

Microwaves do not penetrate all the way through larger volumes of food - the heating is done in the outer 1-2cm. Heating the middle is done by conduction (and by convection if the food is a fluid). If you pile in energy faster than it can conduct all the way through, you will have a burned outside and a cold middle.

Domestic microwave food products are not designed to be heated in

2kW ovens. Many would fail to cook properly/safely. Commercial microwave food products (some anyway) are designed to be heated in 2kW microwaves.

And in reference to your other post, it's not simply a matter of dividing the cooking time by two. The amount of energy absorbed by a food product also depends on the surface area exposed to the microwaves (1 pea in a 2kW oven will not absord 2kW), so the cooking time in a 2kW oven depends on the size and shape of the item - it would have to be calculated by the manufacturer and included on the packaging, but in practice, most domestic food products will not have sufficient heat conduction to be able to absord 2kW and cook properly.

[William Gothberg]

Conventional ovens have to heat the food from the outside. Microwaves heat all the way through.

[William Gothberg]

That could be done with a transformer, with a few tappings to allow lower power.

I never have that problem, water (which most foods are primarily made of) conducts pretty quick.

Most meals are way bigger than a pea. Everything I cook is in a dish and about 1 inch deep. I'm sure that most if it would be hit by microwaves directly.

[Dean Hoffman]

Well, the microwave cooking instructions on a lot of things say to stir halfway through cooking time. That would lead me to think microwaves have the same issue as conventional ovens with the evenness factor.

[William Gothberg]

They heat about an inch into the food. Good enough unless it's a huge meal.