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Using a 60hz mains device in the UK

Using a 60hz mains device in the UK

Using a 60hz mains device in the UK

(OP)
On holiday in South Korea I noticed a plethora of coloured energy saving bulbs which looked rather aesthetically pleasing.  I bought a blue one and brought it home (UK) plugged it into the UK mains (into a circular screw thread lamp fitting) and it appears to be working fine. The operating conditions on the side of the box said 220v at 60 hz which is what I believe S. Korean electricity runs at.

Now, a rice cooker from Korea has just arrived, telling me that it too will operate at 220v/60hz (500w at 2.3a)....

Clearly, a lightbulb is a less complex object than a rice cooker... Do I require a converter, or will the rice cooker work okay on my UK mains? Are there risks? Possible component stress? Anything I should be aware of (apart from changing the plug...)

Your valuable experiences much appreciated

monchavo

RE: Using a 60hz mains device in the UK

Rice cooker is even a simpler device than a bulb, believe it or not. It is just a resistive heater coil and could not care less for frequency.



RE: Using a 60hz mains device in the UK

Interestingly, a passive device like a heater is happier on a lower voltage; less stress. A switched-mode supply would try to keep the power constant and therefore the current would increase but a simple resistive load can't do that.

Just to make your day I should point out that bringing a non-CE marked electrical appliance into the UK (effectively importing it) and putting it into service is actually a criminal offence. If you get electrocuted the government will probably imprison your dead carcass just to make a point.

In the case of a rice cooker the safety aspects are of more concern than the EMC directive.

RE: Using a 60hz mains device in the UK

A ricecooker is less complex than the lightbulb... unless said ricecooker has a digital controller (welcome to the age of sub-$1 throw-away microcontrollers).

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Using a 60hz mains device in the UK

(OP)
Splendid. When I said more complex, I meant more parts (including some that move). Thank you for the excellent advice. I knew I could count on you wonderful chaps.

Kimchee, anyone? :)

RE: Using a 60hz mains device in the UK

Moving parts on a rice cooker? Well that's a diferent story then. Moving parts implies motors and motors are definately affected by frequency and voltage. What the heck moves on your rice cooker? The lid?

http:/www.jraef.com
Eng-Tips: Help for your job, not for your homework  Read FAQ731-376 pirate

RE: Using a 60hz mains device in the UK

Maybe it's a jap bike. They are sometimes referred to as "rice cookers". Lots of moving parts there...

Gunnar Englund
www.gke.org

RE: Using a 60hz mains device in the UK

Not sure about your rice cooker, if it just has a heating element it should be fine.

If it has a motor driven timer, it may not be too happy, apart from running slow, the motor will run hotter. None of that may matter in practice.

RE: Using a 60hz mains device in the UK

We've missed the point that the UK with its notional 230V 50Hz supply still pumps out 240V in almost all locations. The 230V nominal supply in Europe has very broad tolerances to allow the distribution infrastructure of Europe (historically 220V) and the UK (historically 240V) to comply with the new 'standard' of 230V. Eventually Europe will all become 230V as assest on the netwrok are replaced, but I doubt it will be within my lifetime.

The 220V lamp or heater is running at nearly 10% overvoltage. The rice might cook a little quicker, but the filament lamp will not last as long. Enjoy it while it is working!

----------------------------------
  I don't suffer from insanity. I enjoy it...

RE: Using a 60hz mains device in the UK

(OP)
Other users of similar Korean produced rice cookers in the UK have expressed the same - that their cookers fail every few years and have to be replaced, due to the filaments giving up the ghost. The 10% extra voltage I suppose is a good reason!

RE: Using a 60hz mains device in the UK

If the cooker parts run hotter, the rice will get cooked faster..no problem.

:) could not resist!!!

RE: Using a 60hz mains device in the UK

Rice burner?

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"It's the questions that drive us"
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

RE: Using a 60hz mains device in the UK

I still want to know what moving parts there are in a rice cooker...

http:/www.jraef.com
Eng-Tips: Help for your job, not for your homework  Read FAQ731-376 pirate

RE: Using a 60hz mains device in the UK

(OP)
The lid? :)

RE: Using a 60hz mains device in the UK

I think you made a great job there Jeff. But I miss water level sensor. Or is that included in the weight sensing? I see a problem differentiating between water weight and rice weight.

Tangent alert!!!

Can you please add the following blocks to your diagram:

1  A sensor and comparator for rice.

2  A sensor and comparator for rice + water

3  A sequential circuit that a)promts for rice  b)prompts for water  c)checks that lid is on   d)starts cooking.

Gunnar Englund
www.gke.org

RE: Using a 60hz mains device in the UK

I can't believe I failed to spot the mismatched voltage direction. I was answering in terms of the applied voltage being lower than rated!

10% over-voltage means 20% over power and therefore 20% over-temperature =VERY BAD. Now typically devices are rated for 10% over-voltage, at least, so it shouldn't immediately fail, but like I said earlier you are asking for trouble legally. Suppose a guest touches it and gets an electric shock. You will be in deep doo-doo legally as you are already a criminal for importing it.

RE: Using a 60hz mains device in the UK

(OP)
I posted this thread in order to understand the implications of connecting this device to the UK mains, and any detrimental effect that that might have on the unit.....

Not sure I follow the logic of why does 10% over-voltage means 20% over power?

Clearly a hotter rice cooker is going to cook the rice quicker, I shall have to factor that into my assessment when I am adding rice and water.... :)

In regards to your comment about a "guest touching it and gets and electric shock", is the fact that the unit is operating outside of it's designed parameters going to make a shock more likely?

RE: Using a 60hz mains device in the UK

1.1 squared is 1.21 - that's why power is 21 percent higher when voltage is ten percent higher.

Now, the 220-> 230 vs 240 -> 230 V change is over. So even UK should be close to 230 V. But, of cours, ScottyUK knows. He lives there.

Gunnar Englund
www.gke.org

RE: Using a 60hz mains device in the UK

How are you going to cook the rice faster? 212 degrees is as far as you're going.  It might heat to a boil faster but also might drive off the water faster leaving too little for proper rice absorption.

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

RE: Using a 60hz mains device in the UK

Thats why I am not a cook...:)

RE: Using a 60hz mains device in the UK

Hi Skogs,

The UK is still firmly 240V, although 'officially' it is now 230V! We're just right up at the very top end of the permitted tolerance of +10% on nominal. 230+10% = 253V. Our old standard was 240V +6% which conveniently is 254V. Thus the UK infrastructure technically does comply with the new requirements. The cost of changing all the 240V distribution transformers for a lower voltage equivalent en-masse would be astronomical. They'll just get replaced as they reach the end of their service life. For a distribution transformer that could be 40 or 50 years.

----------------------------------
  I don't suffer from insanity. I enjoy it...

RE: Using a 60hz mains device in the UK

Hi Scotty,

I have noticed that the power factor for some motors has gradually got worse during the 220 -> 230 V adaption (which took 15 - 20 years and also means that 380 V is now 400 V)). Also, many incandescent lamps seemed to live shorter lives until we got the 230 V rated ones everywhere.

I will bring a DMM next time I go to UK (heck, don't I always bring scopes and voltmeters and what have you wherever I go?) so I can verify that high mains voltage. But you have gone metric? Haven't you?

Gunnar Englund
www.gke.org

RE: Using a 60hz mains device in the UK

Yeah, we're definitely metric! I guess there will be a few transformers at the new voltage where modern development has occurred, but I've just checked my house mains and it is 242V tonight. It was built in 1993, so it's not old, but not young enough to have seen the new standard.

----------------------------------
  I don't suffer from insanity. I enjoy it...

RE: Using a 60hz mains device in the UK

logbook wrote:

Quote:

Just to make your day I should point out that bringing a non-CE marked electrical appliance into the UK (effectively importing it) and putting it into service is actually a criminal offence. If you get electrocuted the government will probably imprison your dead carcass just to make a point.

Actually, don't they just brand your forehead (aka for'hd) with a "V"?

RE: Using a 60hz mains device in the UK

I have seen a lot of electrical equipment brought over from Hong Kong, Singapore, Japan into Australia and run on Australian 240V 50Hz (yes I know Australia is also now supposed to be 230V).  

These electrical appliance range from clocks, radios, hifi, video games to rice cookers.  

So far all the rice cookers operate fine and cook properly. They don't cook any faster as far as I can see.   

Occasionally some of the simpler appliances with small transformers in them such as radio clocks work fine but do seem to run slightly hotter.  In one case the thermal fuse monitoring the transformer failed.

I won't even mention how some people even just bend the pins of the plug to fit into Australian power points!!!

RE: Using a 60hz mains device in the UK

If your recently arrived rice cooker from Korea fails to do the job, send her back.  

I am sure there are plenty of other Korean ladies that know how to cook rice, whatever the mains frequency or voltage.

RE: Using a 60hz mains device in the UK

(OP)
Very funny, Warspeed.
My girlfriend would readjust your internal voltage if she heard you saying that. :)

RE: Using a 60hz mains device in the UK

As itsmoked said, it will not cook the rice any faster, rice cooks as fast as it cooks. The heater elements will get hotter faster, but that just means they will get cycled on and off more rapidly to maintain the required temperature setting.

Gunnar,
As much as I enjoyed your thinking that I had made that nice block diagram, I must admit to plagiarizing it from a rice cooker mfrs website. I imagine that the weight sensor is total combined weight of rice and water so that it can tweak the time for the batch size. The cook must externally determine the rice/water ratio based on volumetric measurement as they have for countless eons. Some things don't need improvement. I also find it interesting that they sense the upper lid temp and feed that into the comparator with the cooker temp, probably to tweak for ambient conditions. For instance, if cooking rice in a igloo, the heat losses through the top might make it take longer to cook. That also might possibly be your detection circuit for the lid left up!

I still want to find the moving parts though... Motorized stirring paddles? Fluffing fork?

http:/www.jraef.com
Eng-Tips: Help for your job, not for your homework  Read FAQ731-376 pirate

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