electricity question 220-110v Hertz

Factual Questions
1

Hi Folks, My question deals with the use of 110 volt made in USA appliances in Europe on a 220volt network.

I have had success over the years in using almost any and all appliances from the USA with a transformer here in Europe.

Here are the exceptions:

About 30 years ago a friend of mine brought his record player over from Chicago and plugged it in in Spain with a transformer and tried to make it play records. Remember those vinyl thingmebobs?

Well the turntable played them a mite slowly, and I think the answer we finally arrived at was that it was a question of Hertz. USA hertz is 60 and European Hertz is at 50. So turntables were out.

Then a few years ago someone in the USA gave me a small second hand broiler which i plugged in here and it would never get really hot. So I think I learned that resistances were dependent upon hertz as well and would not perform well here.

So now I get to the crux of my question.

I am looking at waffle irons and I was wondering if one made for the USA market would function in Europe.

thanks

2

Frequency shouldn’t matter for a simple heating device. Unless it has a timer - many simple timers run off the line frequency, so it will run slower in Europe. Just re-label the dial to compensate and you should be fine. (Devices sold in Japan often have two sets of labels on the timer dial because half the country uses 50Hz, and the other half 60 Hz).

However I’m concerned about your transformer. Are you sure it has sufficient capacity (wattage) to power the waffle iron? (Or the broiler, for that matter.) Cooking appliances use far more power than electronic devices.

3

Can you say “smoke?”

The waffle iron for the US is made for 110Volts, and as you noted, Europe uses 220Volts. The waffle iron will get way too hot and most likely burn out the heating coil in no time flat.

You can get conversion units from Radio Shack cheap that will work for a waffle iron, but don’t use for anything else - they are cheap because they use a poor method of converting the voltage, and most devices (motors, and electronics, etc.) won’t like what the cheap converters put out.

4

“220, 221-- whatever it takes”.

Someone had to say it.:slight_smile:

5

I’m sorry, I haven’t been very clear. I have a 1000 watt transformer which I use to power various of these applainces. 220 -->110.

i know I won’t burn out the appliance, what I need to know is if it’ll function.

thanks.

6

Yes, IF your appliance(s) require 1000 W or less. Check the rating plate on the appliance in question. This is usually found on the back or the bottom of the unit, and specifies input voltage and frequency, and either current draw in amps or power in watts (or rarely, both). If the specification is in amps, divide the input voltage by the amps to arrive at the maximum wattage.

7

so the hertz won’t matter?

I guess my basic question boils down to:

Doesn’t a waffle iron run on resistences, and is a resistence affected by the differrence in hertz?

8

Resistance is not affected by frequency (what you are calling hertz).

9

MULTIPLY the voltage times the amperage, for an approximation of the power (watts). It’s an approximation because it’s AC current, so any heating coil inductance will cause the current and voltage to be out of phase. That’s the reason there is a distinction between the VA [volt-amp] and Watt power ratings of electronic gear.

For DC: Amp*Volts=Watts exactly.

The two relevant definitions are Ohm’s Laws

voltage = current (amps)* resistance (ohms)
Power (watts) = volts * amps (current)

frrom these you can also derive useful relations like:
Power = volts^2 / resistance = current^2 * resistance

Now, as I noted, this only works out simply when you’re talking about DC. When you’re using AC line current, the voltage is always changing, and the current change may lead or lag the voltage change. Also capacitance and inductance cause an additional effect that is very much like resistance called reactance. In fact, resistance and reactance are usually lumped to gather as “impedance” in circuits at higher frequencies (e.g. audio or RF circuits).

Capacitive reactance goes up with frequency. Inductive reactance goes down with frequency.

For a basic heating circuit, there is probably negligible capacitance, and quite possibly negligible inductance as well, though some heating coils have modest inductance The primary heating is through resistance only

(Some special heating devices operate entirely through induction - but not the cooking gear you’re talking about. Inductive heating is responsible for the parasitic heat of a transformer, the operation of some so-called diathermy machines, etc.)

10

A little more detail:
Inductive reactance (X[sub]L[/sub]) = 2πf [frequency] * L [inductance in Henrys]
Capacitive Reactance (X[sub]C[/sub]) = 1/ (2πf * C [capacitance in farads])

To add capacitive and inductive reactances:
X[sub]total[/sub]= |X[sub]C[/sub] X[sub]C[/sub]|

Now you may be thinking "wait a minute, if I subtract the reactances, then I could simply set them equal, and not have any reactance at all. Guess what, you can. In fact any combination of capacitance and inductance will cancel out at some frequency. This is called the resonant frequency. The old unpowered crystal radio tuners used this fact: at the resonant frequency there was very zero reactance (and the circuit had very low resistance) the consecutive radio waves could pile up on each other until voila! you get a signal large enough to be audible with those old earplugs.

Adding resistance and reactance is a little more complicated:
impedance= sqrt( Resistance^2 + Reactance^2) [like the Pythagorean theorem]

EXAMPLE:
Using Ohm’s Law, we can calculate that a 1200W resistive heating coil that works ar 120V must have a resistance of 0.1 ohms

That would be DC, not AC voltage, but when we say 120VAC, we mean 120 V RMS - or basically an AC voltage rating that does the same work as 120V DC (it’s actually a sine wave with peak values of +/- 170V)

It’s a pretty good approximation for a heating device.

A Henry is a pretty honking large unit. Almost all electronic inductors are in the range of micro- or milli- Henries. (The powerful magnetic coils of large electric motors or transformers are barely in the Henry range)

Plug that into the reactance equation, and you’ll see that small inductances don’t create much reactance at 50 or 60 Hz. The difference between 50 and 60 hertz is going to be even smaller, and when you add the reactance to the resistance we calculated using the impedance equation, you find it has an even tinier effect.

Most heating coils are a high resistance wire (like Nicrome) inside a non-flammable high temperature insulator like fiberglass or asbestos, and usually sealed in another layer of metal for durability.

I don’t know of any household inductive heating coils that operate directly at 50/60 hz anyway. Low frequencies are inefficient for inductive heating. Inductive heaters usually have special drivers that create a higher frequency AC current - and that’s not cheap.

I’m sure there is some application for an inductive heater at 50/60 Hz, and I’d like to hear about them. I’m drawing a blank.

11

The Repair FAQ has a page on international power issues, including section on resistive load issues. Not much of relevance regarding the waffle iron issue. But please read other relevant sections, as there may be more going on than just resistance.

50 vs. 60 does matter in many appliances. E.g., Japan uses 50Hz and for many people who get grey market Japanese electronics, they sometimes work, and they sometimes burnout. The standard power supplies in VCRs and such just run too hot.

12

The reason the turntable didn’t work is that it most likely had what is called a shaded pole motor induction motor.
These are very simply induction motors that can work from a single pahse supply, and like all induction motors, its speed is tied to the frequency of the supply.

This can be corrected by using different size pulley ratios i it is a belt drive.

As for electronics, it really depends.
Sometimes they can stand a lower frequency, and other times not.
The lower frequency generally works out as a lower voltage output from the mains transormer within the appliance.

Another less obviously forseeable effect is that mains transformers are designed for maximum efficiency at a particyular frequency, and if you go outside that range they can get very hot due to too little X[sub]L[/sub] which then allows too much current through the windings.

As for a waffle iron, well heater elements are pretty simple affairs, given an input transormer such as the one you describe should be ok, but if it has a timer this may not run at the rate you expect.

13

I knew that :smack:

And I didn’t mention the approximation bit, because with resistance heating devices, like the OP was asking about, it isn’t necessary. In this case Watts = VA to a very close approximation. Inductive reactance at 50 or 60 Hz is negligible for these sorts of things.

14

I used almost every US 110v appliance you can think of overseas, including a washing machine (and a waffle iron), without significant problems. Motorized appliances won’t run at the same speed and may suffer some long term damage, but heating elements were unaffected. You are more likely to have problems with voltage fluctuations on your electronic equipment, depending on where you live. Most electronics these days are rated 50/60 hz, by the way.

15

Seeing as the real part of the question has been answered, let me do an orthogonal nitpick:
Since about 15 years, the standard voltage in western Europe is 230V.
It used to be 220V in continental Europe and 240V in the UK, but at some point in the late 80’s it was changed to a uniform 230V. However, the tolerances are different on the continent compared to the isles, so that 220V, while accepted on the mainland, would be too low in UK. Similarly 240V is within the tolerances on the island, but not in Europe.

16

I’m not sure what you’re getting at here. If you have a capacitive reactance and an inductive reactance in series, then to get the total, you just add them.

X[sub]total[/sub] = X[sub]C[/sub] + X[sub]L[/sub]

Your formula for capacitive reactance isn’t right either. It should be:

X[sub]C[/sub] = **-**1/(2[symbol]p[/symbol]fC)

In the sheathed elements you refer to, the insulator is almost always MgO.

17

This is true for magnitude. But to keep things simple I prefer to use the complex reactance:

Z[sub]C[/sub] = 1/(j[symbol]w[/symbol]C) = -j/([symbol]w[/symbol]C)

KP:
Instantaneous voltage x instantaneous current is always equal to instantaneous power regardless of whether it is AC or DC. The problem is when you try to calculate the average power of an AC signal based on uncorrelated/unsynchronized voltage and current measurements. If you don’t take the phase difference into account, and/or you don’t use true RMS meters, there’s a good chance you will get lots of error (unless there’s zero reactance). FYI, the most straightforward method for measuring real power is to simultaneously sample the voltage and current using a high speed ADC, multiply the each voltage-current pair (to get instantaneous power), and then average all the instantaneous powers.

18

Hang on. When you mean impedance, just say “impedance”. Impedance is a complex quantity. Resistance and reactance are both real quantities.

Z = R + jX

R = Re{ Z }
X = Im{ Z }

You mentioned |Z|, which is another real quantity. In this case, it happens that Im{Z} = |Z|. So while you say that “this is true for magnitude”, it just happens to be true in this particular case.

I was talking specifically about reactance, and what I said was true for reactance.

19

Yes, yes, you’re correct. I meant to say “impedance,” not reactance.