Inverter to drive microwave
 

Any reliability issues concerning a new Sharp R-1540 microwave to power
it off a square wave inverter when camping? Is there any real
difference between "square wave" and "modified square wave" inverters?

Thanks

Tut

In article .com,
cnctut wrote:
Any reliability issues concerning a new Sharp R-1540 microwave to power
it off a square wave inverter when camping? Is there any real
difference between "square wave" and "modified square wave" inverters?

You're into a fairly chunky invertor to power a decent microwave. And a
chunky battery to power it. Surely a gas or paraffin stove is much more
suitable for camping?

--
*Always borrow money from pessimists - they don't expect it back *

Dave Plowman London SW
To e-mail, change noise into sound.

Dave--

The microwave is in an RV--I have multiple generators that would
work--just hate to start them for 2 minute popcorn or 60 sec hot tea.
Thought an inverter might be a quick solution--the RV has 2 D-8
batteries for DC power--1350 amp-hrs each.

Thanks

Tut

"cnctut" wrote in message
oups.com...
Dave--

The microwave is in an RV--I have multiple generators that would
work--just hate to start them for 2 minute popcorn or 60 sec hot tea.
Thought an inverter might be a quick solution--the RV has 2 D-8
batteries for DC power--1350 amp-hrs each.

Thanks

Tut
sounds like you have enough battery power but I have no idea which would be
better for a microwave

"cnctut" wrote in
oups.com:

Any reliability issues concerning a new Sharp R-1540 microwave to power
it off a square wave inverter when camping? Is there any real
difference between "square wave" and "modified square wave" inverters?

Thanks

Tut


Iron-core transformers do not like square waves-the harmonics just generate
excess heat in the core.You would need a hefty inverter to power the
average MW oven;they run about a kilowatt output(~15A@120VAC input),and
with an iron-core transformer,the startup surge would require more inverter
power.

"modified squarewave" inverters generate a stepped version of a sine
wave,reducing the harmonic output.

--
Jim Yanik
jyanik
at
kua.net

"Jim Yanik" . wrote in message
.. .
"cnctut" wrote in
oups.com:

Any reliability issues concerning a new Sharp R-1540 microwave to power
it off a square wave inverter when camping? Is there any real
difference between "square wave" and "modified square wave" inverters?

Iron-core transformers do not like square waves-the harmonics just
generate
excess heat in the core.You would need a hefty inverter to power the
average MW oven;they run about a kilowatt output(~15A@120VAC input),and
with an iron-core transformer,the startup surge would require more
inverter
power.

"modified squarewave" inverters generate a stepped version of a sine
wave,reducing the harmonic output.

An inverter microwave might work better since they rectify AC to DC.
--
N

Jim Yanik wrote:
"cnctut" wrote in
oups.com:

Any reliability issues concerning a new Sharp R-1540 microwave to
power
it off a square wave inverter when camping? Is there any real
difference between "square wave" and "modified square wave"
inverters?

Thanks

Tut


Iron-core transformers do not like square waves-the harmonics just
generate
excess heat in the core.You would need a hefty inverter to power the
average MW oven;they run about a kilowatt output(~15A@120VAC
input),and
with an iron-core transformer,the startup surge would require more
inverter
power.

I'm ok with a little bigger inverter if you think the extra heat for
the microwave transformer won't be a problem over one 2 or 3 minute
duty cycle.



"modified squarewave" inverters generate a stepped version of a sine
wave,reducing the harmonic output.

Are you saying a modified square wave inverter has multiple stair steps
to max voltage vice one large step for older pure square wave
inverters? Or does the modified inverter produce a wave similiar to the
first 2 or 3 sums of a Fourier series (sorry, I don't mean to sound
like a Jacka--?)

Thanks

Tut



--
Jim Yanik
jyanik
at
kua.net

NSM wrote:
"Jim Yanik" . wrote in message
.. .
"cnctut" wrote in
oups.com:

Any reliability issues concerning a new Sharp R-1540 microwave to
power
it off a square wave inverter when camping? Is there any real
difference between "square wave" and "modified square wave"
inverters?

Iron-core transformers do not like square waves-the harmonics just
generate
excess heat in the core.You would need a hefty inverter to power
the
average MW oven;they run about a kilowatt output(~15A@120VAC
input),and
with an iron-core transformer,the startup surge would require more
inverter
power.

"modified squarewave" inverters generate a stepped version of a
sine
wave,reducing the harmonic output.

An inverter microwave might work better since they rectify AC to DC.
--
N

NSM--isn't there some 120vac in the microwave unit somewhere--AC fans,
motors, etc?

Jim Yanik wrote:
"cnctut" wrote in
oups.com:

Any reliability issues concerning a new Sharp R-1540 microwave to
power
it off a square wave inverter when camping? Is there any real
difference between "square wave" and "modified square wave"
inverters?

Thanks

Tut


Iron-core transformers do not like square waves-the harmonics just
generate
excess heat in the core.You would need a hefty inverter to power the
average MW oven;they run about a kilowatt output(~15A@120VAC
input),and
with an iron-core transformer,the startup surge would require more
inverter
power.

"modified squarewave" inverters generate a stepped version of a sine
wave,reducing the harmonic output.

--
Jim Yanik
jyanik
at
kua.net


Jim

Thanks--I got off my lazy kester and did a google and found the wave
shape for a modified square wave inverter. Appreciate your input.

Tut

"cnctut" wrote in message
oups.com...

NSM--isn't there some 120vac in the microwave unit somewhere--AC fans,
motors, etc?

Sure, but they're shaded pole motors - should be OK.
--
N

"cnctut" wrote in message
oups.com...
Thanks--I got off my lazy kester and did a google and found the wave
shape for a modified square wave inverter. Appreciate your input.

A modified sine wave doesn't have a 3rd harmonic, and the idea is that
eliminating is goes a long way towards reducing overheating in transformers
(since the higher the harmonic, the more it's naturally surpressed from the
core's self inductance).

---Joel Kolstad

"cnctut" wrote in
oups.com:


Jim Yanik wrote:
"cnctut" wrote in
oups.com:

Any reliability issues concerning a new Sharp R-1540 microwave to
power
it off a square wave inverter when camping? Is there any real
difference between "square wave" and "modified square wave"
inverters?

Thanks

Tut


Iron-core transformers do not like square waves-the harmonics just
generate
excess heat in the core.You would need a hefty inverter to power the
average MW oven;they run about a kilowatt output(~15A@120VAC
input),and
with an iron-core transformer,the startup surge would require more
inverter
power.

I'm ok with a little bigger inverter if you think the extra heat for
the microwave transformer won't be a problem over one 2 or 3 minute
duty cycle.



"modified squarewave" inverters generate a stepped version of a sine
wave,reducing the harmonic output.

Are you saying a modified square wave inverter has multiple stair steps
to max voltage vice one large step for older pure square wave
inverters?

Yes,AFAIK.




--
Jim Yanik
jyanik
at
kua.net

Jim

Thanks for the response--and thanks for not reprinting the Fourier
stuff. ;-))

Tut

The Don Rowe inverter FAQ has a question about running an inverter off
of a microwave:

http://www.donrowe.com/inverters/inverter_faq.html

Unfortunately it's rather light on details. Anyway, it should work, but
you'll probably need a 2k running, 5k surge inverter to run it. They
are out there and actually not terribly expensive any more. Sinewave
units at that size are still pricey. A Xantrax 1750 for instance is
around $300 with the cable necessary to install it, and will run most
reasonably sized microwave ovens for as long as your batteries hold
out.

-Keith

Keith--thanks

Tut

"Jim Yanik" . wrote in message
.. .
"cnctut" wrote in
oups.com:

Any reliability issues concerning a new Sharp R-1540 microwave to power
it off a square wave inverter when camping? Is there any real
difference between "square wave" and "modified square wave" inverters?

Thanks

Tut


Iron-core transformers do not like square waves-the harmonics just
generate
excess heat in the core.You would need a hefty inverter to power the
average MW oven;they run about a kilowatt output(~15A@120VAC input),and
with an iron-core transformer,the startup surge would require more
inverter
power.

"modified squarewave" inverters generate a stepped version of a sine
wave,reducing the harmonic output.




I have a 1500W inverter I've been trying to sell for $75 for a while now so
they're obviously not hard or expensive to acquire. It runs a microwave just
fine, transformer buzzes a bit louder but how often does one get run for
more than a few minutes?

"James Sweet" wrote in message
news:0nDhe.6622$Y12.5595@trnddc09...

I have a 1500W inverter I've been trying to sell for $75 for a while now
so
they're obviously not hard or expensive to acquire. It runs a microwave
just
fine, transformer buzzes a bit louder but how often does one get run for
more than a few minutes?

And it's not impossible to smooth the output either.
--
N