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110V to 100V

A

atasaka

Jan 1, 1970
0
I made the mistake of bringing a fuzzy logic rice cooker back with me from
Japan and thought I could use a converter I already had at home but when I
looked at the specs on the cooker, it says 100V, 1100W, 20A. My converter
is rated for under 100W. So I found someone selling a 110V to 100V step
down transformer at 1500VA and 15A max. Is 1500VA the same as 1500W?
Will the 5A make any difference? I'm pretty clueless when it comes to
this stuff but want to make sure I don't do anything that will damage the
cooker since its electronics are quite complex as far as rice cookers go.
The seller is not a dealer so he is not sure either. Any help would be
appreciated. Thanks!
 
D

DarkMatter

Jan 1, 1970
0
I made the mistake of bringing a fuzzy logic rice cooker back with me from
Japan and thought I could use a converter I already had at home but when I
looked at the specs on the cooker, it says 100V, 1100W, 20A. My converter
is rated for under 100W. So I found someone selling a 110V to 100V step
down transformer at 1500VA and 15A max. Is 1500VA the same as 1500W?
Will the 5A make any difference? I'm pretty clueless when it comes to
this stuff but want to make sure I don't do anything that will damage the
cooker since its electronics are quite complex as far as rice cookers go.
The seller is not a dealer so he is not sure either. Any help would be
appreciated. Thanks!


100V at 20A is 2kW. A single 120 volt line at 15 amps is only 1.8kW

I'd find out what the thing really uses. Also, are you sure that
your mains are at 110V? A 110 to 100 step down xfmr is only a 120 to
109V conversion. The heating element in the cooker wouldn't mind so
much, but the front end supply and control electronics for it may.

Anyway, their 1100W claim doesn't jibe with their claim of a 20 Amp
draw. One or the other is not correct. Either the unit only draws 1.1
amps, or somebody doesn't know how to do the math in that japanese
rice cooker factory. Maybe he was using fuzzy logic too! :]
 
M

Mjolinor

Jan 1, 1970
0
Richard Crowley said:
"VA" is the acronym for "volt-amps" and is generally equivalent
to "W" (watts). Calculated by multiplying the volts and amps.

I would just try the 1500VA transformer and monitor it to see if
it overheats in use.

The numbers "100V, 1100W, 20A" don't really compute.
I believe the 100V because that is the domestic standard
in Japan. And the 1100W *sounds* reasonable. But 1100W
at 100V is only 11A (1100W divided by 100V). Dunno where
the "20A" comes from. Maybe it is an indication that they
recommend using it on a dedicated 20A branch circuit.

Taking them at their word (at least the parts we choose to
believe :), it may draw only 11A in which case, the 15A
transformer would be adequate.

AFAIK the tolerance of the power supply voltage SHOULD mean that it will
work OK off 110. If it were mine I would certainly try it, maybe through a
variac slowly if ti were very expensive but i am pretty certain it would be
OK.

That should get me a flaming :)
 
Z

Zak

Jan 1, 1970
0
atasaka said:
So I found someone selling a 110V to 100V step
down transformer at 1500VA and 15A max. Is 1500VA the same as 1500W?
Will the 5A make any difference?

It shouldn't be an expensive transformer by the way. You could use a 110
to 10 volt transformer of 150 (or 200) VA.

The tricK: the primary is wired to your 110 volts. The secondary is put
in series with your 110 volts, so that it subtracts (measure this...).

The transformer is asked to deliver 15 (or 20) amps at 10 volts. That's
a 150 to 200 watt transformer.


Thomas
 
A

atasaka

Jan 1, 1970
0
After reading your post, I looked at the rice cooker again and next to the
20A in katakana characters, I think it reads "fuse" but I'm not too sure.
Could this mean the rice cooker has a fuse built in that can handle up to
20A? Thanks for everyone's help.
 
J

Jerry G.

Jan 1, 1970
0
Your rice cooker will pull 11 Amps at 100 V and if you run it on 120 V
it will pull about 13 amps. The reason for the 20 Amps being indicated,
is that in Japan, the standard panel breaker for home kitchen appliance
use is 20 Amps. Here in North America the standard is 15 Amps. As for
the transformer, you should be okay with the 1500 VA unit.

The cooker would probably work on 120 V, but it will be a bit hard on
it. I would prefer to use the proper rated voltage. From 100 to 120 V
there is a 20% difference. This is a lot for continuous use. Running
the cooker on a higher voltage may definitely lower the life span of the
unit.

I am curious to know the company that made your rice cooker. Before
Sony got in to the TV and electronics business, they were a rice cooker
and small appliance manufacture. Infact, they were one of the best made.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
==============================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
Instruments http://www.zoom-one.com/glgtech.htm
==============================================
I made the mistake of bringing a fuzzy logic rice cooker back with me
from
Japan and thought I could use a converter I already had at home but when
I
looked at the specs on the cooker, it says 100V, 1100W, 20A. My
converter
is rated for under 100W. So I found someone selling a 110V to 100V step
down transformer at 1500VA and 15A max. Is 1500VA the same as 1500W?
Will the 5A make any difference? I'm pretty clueless when it comes to
this stuff but want to make sure I don't do anything that will damage
the
cooker since its electronics are quite complex as far as rice cookers
go.
The seller is not a dealer so he is not sure either. Any help would be
appreciated. Thanks!
 
M

Mjolinor

Jan 1, 1970
0
Jerry G. said:
Your rice cooker will pull 11 Amps at 100 V and if you run it on 120 V
it will pull about 13 amps. The reason for the 20 Amps being indicated,
is that in Japan, the standard panel breaker for home kitchen appliance
use is 20 Amps. Here in North America the standard is 15 Amps. As for
the transformer, you should be okay with the 1500 VA unit.

The cooker would probably work on 120 V, but it will be a bit hard on
it. I would prefer to use the proper rated voltage. From 100 to 120 V
there is a 20% difference. This is a lot for continuous use. Running
the cooker on a higher voltage may definitely lower the life span of the
unit.

I thouhght the original post said he wanted to run it from 110 volts but I
can't find it to check?
 
M

Mjolinor

Jan 1, 1970
0
Richard Crowley said:
...

Domestic power in North America is variously referred to as:
110, 115, 117, 120 V. Likely varies even wider than that.
Don't try to calibrate your voltmeter from the power line!

I must have missed the bit where he said he was in North America as well.
 
S

Steven

Jan 1, 1970
0
DarkMatter said:
100V at 20A is 2kW. A single 120 volt line at 15 amps is only 1.8kW

brrr. Wrong answer.
100V at 20A is 2kVA and has to be multiplied with cos(phi) to get real power
(in W or kW).
For resistive loads cos(phi) = 1, so then -- and only the! -- the 2kVA =
2kW.
If cos(phi) = 0 (pure inductive or capacitive loads) the 2kVA = 0W. Nothing,
zilch, nada
 
D

DarkMatter

Jan 1, 1970
0
brrr. Wrong answer.
100V at 20A is 2kVA and has to be multiplied with cos(phi) to get real power
(in W or kW).
For resistive loads cos(phi) = 1, so then -- and only the! -- the 2kVA =
2kW.
If cos(phi) = 0 (pure inductive or capacitive loads) the 2kVA = 0W. Nothing,
zilch, nada


It is a purely resistive load, dipshit.
 
H

Harry Conover

Jan 1, 1970
0
Steven said:
brrr. Wrong answer.
100V at 20A is 2kVA and has to be multiplied with cos(phi) to get real power
(in W or kW).
For resistive loads cos(phi) = 1, so then -- and only the! -- the 2kVA =
2kW.
If cos(phi) = 0 (pure inductive or capacitive loads) the 2kVA = 0W. Nothing,
zilch, nada

Given that rice cookers today are pretty inexpensive, and power
converters are not, I tend to believe that this guy would be well
advised to simply purchase a new rice cooker!

Harry C.
 
L

Lizard Blizzard

Jan 1, 1970
0
Richard said:
"VA" is the acronym for "volt-amps" and is generally equivalent
to "W" (watts). Calculated by multiplying the volts and amps.

I would just try the 1500VA transformer and monitor it to see if
it overheats in use.

The numbers "100V, 1100W, 20A" don't really compute.
I believe the 100V because that is the domestic standard
in Japan. And the 1100W *sounds* reasonable. But 1100W
at 100V is only 11A (1100W divided by 100V). Dunno where
the "20A" comes from. Maybe it is an indication that they
recommend using it on a dedicated 20A branch circuit.

Taking them at their word (at least the parts we choose to
believe :), it may draw only 11A in which case, the 15A
transformer would be adequate.

Maybe it uses a 100VAC 20 amp heating element with a TRIAC in series,
which never allows the full continuous 20 amps thru. I.e. it's really a
PWM controlled heater. And it might actually draw 20A peak for
fractions of a second.
 
L

Lizard Blizzard

Jan 1, 1970
0
Harry Conover wrote:
[snip]
Given that rice cookers today are pretty inexpensive, and power
converters are not, I tend to believe that this guy would be well
advised to simply purchase a new rice cooker!

Another thought. Advertise that you have a rice cooker that you brought
from Japan recently and you're looking to trade for a U.S. one for
someone who is going to Japan. Equivalent make, model, capacity, etc..
 
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