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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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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 |
#2
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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. |
#3
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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 |
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"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 |
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"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 |
#6
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"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 |
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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 |
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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? |
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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 |
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"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 |
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"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 |
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"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 |
#13
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Jim
Thanks for the response--and thanks for not reprinting the Fourier stuff. ;-)) Tut |
#14
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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 |
#16
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"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 $75 for a while now so they're obviously not hard or expensive to acquire. It runs a microwave just fine, transformer buzzes a bit louder but how often does one get run for more than a few minutes? |
#17
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"James Sweet" wrote in message news:0nDhe.6622$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 |
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