Re: [tlug] [OT] Taking appliances between J and US power

[Jim <jep200404@example.com>]

By the way, which rice cookers have computer interfaces have good 
Linux driver support? 

David J Iannucci wrote:

> we've ... a suihanki that we bought and used in Japan,
> then brought to the US and ran on a transformer for several years.  

Did y'all remember to set the 50Hz/60Hz switch to the correct position? 
I just got an old rice cooker from a Japanese person who had been using it 
for the last few years in the US. The frequency switch was in the wrong 
position for the US where she had been using it for a few years. 

Mere transformers change the voltage, 
but not the frequency of the electrical power supplied. 

Most resistive heating elements don't care at all about the power frequency. 

Only the control electronics should care, and even then, only a little 
bit and only for ancient designs that use linear power supplies instead 
of modern switching power supplies. It's easy to design switching 
power supplies to work fine with either 50 Hz or 60 Hz automatically. 
The transformers for linear power supplies are usually less tolerant, 
but can be designed to be tolerant of both 50 Hz and 60 Hz power. 

> At one point it seemed the transformer had stopped working, 
> so we just started running the suihanki on US 110v power.  
> It has started to overflow suds, at first only on larger loads 
> and rarely, now more often, and on smaller loads (according to my wife).

This much makes sense. 

The power is related to the _square_ of the voltage 
(albeit reduced by increased resistance at higher temperatures). 
Increased power would likely increase frothing. 

With only a 10% difference in voltage, I would not expect much difference. 
Running a resistive heating device designed for 100 VAC on 110 VAC, 
I would expect about a 20% increase in heating power. 
So at 110 VAC, it would heat up quicker and boil more vigorously, 
and back at 100 VAC, it would heat up slower and boil normally. 

By the way, how do you know that your power is 110 VAC? 
Measure it. I just measured mine. It was 120.1 VAC. 

Running resistive heating devices designed for 100 VAC on 120 VAC, 
would yield about 40% more power. 40% increase in boiling including 
frothing would not be surprising. 

To summarize, running a 100 VAC simple electric rice cooker on 
110 VAC or 120 VAC, is likely to: 

   1. heat the rice quicker, 
   2. can change the cooking characteristics some. 
         (corroborated by wife noticing froth)
         scorching would not be surprising, especially for small loads
   3. shorten the life of the cooker, especially if cheaply made
         (for well made cookers, it shouldn't matter)

> I have convinced myself the transformer is ok, and I'd like to put the
> thing back on it, but my wife has heard from her friends that Japanese
> appliances, after being switched for some time to higher voltage, will
> die if then returned to 100v power. Does anyone know whether there's 
> any reason I should believe this?

No. It sounds like complete utter rubbish. 

Appliances (including rice cookers) do not "remember" or 
"get used to" the power that they are used on. 

I would expect the thing to last longer used on 100VAC. 

> Should [I/we] expect this sort of [bad] result? 

No. 

A 100 VAC rice cooker will last longer when used on 100 VAC than on 
110 VAC or 120 VAC. 

100 VAC appliances do not "get used to" 110 VAC or 120 VAC power. 
Running a 100 VAC rice cooker on 100 VAC after years of running on it 
on 110 VAC or 120 VAC is likely revert back to the old heating 
and cooking characteristics and extend the life of the cooker 
(especially if cheaply made). 

> I *strongly* encourage respondents to respond to me directly, ... 

Why?  http://www.catb.org/~esr/faqs/smart-questions.html#noprivate