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#1
January 15th 04, 06:22 PM
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power transformers
Way back, when I was 7 or 8 years old, (I am 55 now), my dad got me an
electric train set....During that Christmas we were at my Grandparents place and they were on 25 hz power....At home we were on 60 hz power... We had to be at home for me to try out my new train set. What has that got to do with this question?... This.... I have a number of transformers and would like to experiement using then at a higher frequency....let say 500 hz and / or higher..... Would they still work?...I am assuming so... Would they run cooler?.... Could anyone foresee any negative effects?.... Larry ve3fxq |
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#2
January 15th 04, 06:29 PM
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Behold, larry signalled from keyed 4-1000A filament:
Would they still work?...I am assuming so... Yes. Would they run cooler?.... Depends. If the core is of good quality then they'll run cooler. Eddy current effects are more pronounced at higher frequencies. Could anyone foresee any negative effects?.... You may get higher than anticipated secondary voltage. -- Gregg *It's probably useful, even if it can't be SPICE'd* http://geek.scorpiorising.ca |
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#3
January 15th 04, 06:47 PM
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I'd try them, but cautiously. Running a 60Hz transformer at 500Hz will mean
that you have a higher unloaded inductance (good), a higher leakage inductance (bad), lower peak flux in the core (good), higher eddy current losses (bad), etc., etc. The eddy current losses are what will get you in theory, but in practice the smaller power transformers have laminations that seem to be thinner than necessary as a matter of constructional convenience. Hook it up, try it out, look for sparks, smell for smoke, and after a while put one of your less-valuable fingers on the core and see if it's getting hot. Back in the days of tubes it was common to see a moderate-power line transformer used as an output or a modulation transformer. If that's what you're thinking then search around on the web -- I recall a pretty comprehensive article about converting a power transformer to an output or modulation transformer (I can't remember which). I'm too young to have actually done this, but if this is what you're trying maybe you can find the article. "larry" wrote in message .cable.rogers.com... Way back, when I was 7 or 8 years old, (I am 55 now), my dad got me an electric train set....During that Christmas we were at my Grandparents place and they were on 25 hz power....At home we were on 60 hz power... We had to be at home for me to try out my new train set. What has that got to do with this question?... This.... I have a number of transformers and would like to experiement using then at a higher frequency....let say 500 hz and / or higher..... Would they still work?...I am assuming so... Would they run cooler?.... Could anyone foresee any negative effects?.... Larry ve3fxq |
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#4
January 15th 04, 07:11 PM
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First: thanks for the replys....
Second: Sometimes I feel like I must be very dense....what does the following line mean...? Behold, larry signalled from keyed 4-1000A filament I am still trying to figure out the meaning...sorry... Larry "Gregg" wrote in message news:9_ANb.16349$wf1.13504@edtnps89... Behold, larry signalled from keyed 4-1000A filament: Would they still work?...I am assuming so... Yes. Would they run cooler?.... Depends. If the core is of good quality then they'll run cooler. Eddy current effects are more pronounced at higher frequencies. Could anyone foresee any negative effects?.... You may get higher than anticipated secondary voltage. -- Gregg *It's probably useful, even if it can't be SPICE'd* http://geek.scorpiorising.ca |
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#5
January 15th 04, 08:11 PM
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If you look on the back of military equipment and some better test
equipment you'll see that much of it is rated from 50Hz to 400Hz. hank wd5jfr "larry" wrote in message .cable.rogers.com... Way back, when I was 7 or 8 years old, (I am 55 now), my dad got me an electric train set....During that Christmas we were at my Grandparents place and they were on 25 hz power....At home we were on 60 hz power... We had to be at home for me to try out my new train set. What has that got to do with this question?... This.... I have a number of transformers and would like to experiement using then at a higher frequency....let say 500 hz and / or higher..... Would they still work?...I am assuming so... Would they run cooler?.... Could anyone foresee any negative effects?.... Larry ve3fxq |
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#6
January 15th 04, 10:22 PM
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larry wrote:
First: thanks for the replys.... Second: Sometimes I feel like I must be very dense....what does the following line mean...? Behold, larry signalled from keyed 4-1000A filament I am still trying to figure out the meaning...sorry... Larry It is a nonsense phrase his browser tacks on to every message. It takes the name from the previous message and adds the rest. Some people think it is cute, or witty. Others just find it childish. -- We now return you to our normally scheduled programming. Take a look at this little cutie! ;-) http://home.earthlink.net/~mike.terrell/photos.html Michael A. Terrell Central Florida |
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#7
January 16th 04, 03:42 AM
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Way back, when I was 7 or 8 years old, (I am 55 now), my dad got me an
electric train set....During that Christmas we were at my Grandparents place and they were on 25 hz power....At home we were on 60 hz power... We had to be at home for me to try out my new train set. What has that got to do with this question?... This.... I have a number of transformers and would like to experiement using then at a higher frequency....let say 500 hz and / or higher..... Would they still work?...I am assuming so... Would they run cooler?.... Usually if the transformer was designed for a low frequency it will work at a higher one tuil the frequency is so high you run into core losses. If a transformer is designed for a higher frequcncy it will overheat if ran on a much lower frequency. The military used to use about 400 hz AC in the planes so they could save weight on the transformer cores for one reason. |
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#8
January 16th 04, 03:53 AM
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Behold, Michael A. Terrell signalled from keyed 4-1000A filament:
larry wrote: First: thanks for the replys.... Second: Sometimes I feel like I must be very dense....what does the following line mean...? Behold, larry signalled from keyed 4-1000A filament I am still trying to figure out the meaning...sorry... Larry It is a nonsense phrase his browser tacks on to every message. It takes the name from the previous message and adds the rest. Some people think it is cute, or witty. Others just find it childish. Yeah, I just found the default soooooo boring ;-) -- Gregg *It's probably useful, even if it can't be SPICE'd* http://geek.scorpiorising.ca |
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#9
January 16th 04, 03:55 PM
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I have a number of transformers and would like to experiement using then
at a higher frequency....let say 500 hz and / or higher..... Would they still work?...I am assuming so... Would they run cooler?.... Could anyone foresee any negative effects?.... ========================= Running transformers on a higher freq is fine provided the core can manage the higher freq. During the valve era ,aeronautical radio equipment ran on 400 Hz resulting in smaller and hence lower weight transformers. However running power supply transformers at an AC frequency lower than the one they are designed for might cause the laminated core to overheat. In practice : 50 Hz transformers meant for use in Europe and elsewhere can be readily used in the US and Canada. However transformers designed for 60 Hz having 'marginal cores' could overheat when used on a 50 Hz supply. So equipment with 'wallwarts' purchased in the US ,(apart from being suitable for 117 V only ) I never use on a 50 Hz supply system. Nowadays with much equipment having a switch mode power supply , the frequency / voltage problem no longer exists. Frank GM0CSZ / KN6WH |
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#10
January 17th 04, 12:36 AM
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In article le.rogers.com,
"larry" writes: Way back, when I was 7 or 8 years old, (I am 55 now), my dad got me an electric train set....During that Christmas we were at my Grandparents place and they were on 25 hz power....At home we were on 60 hz power... We had to be at home for me to try out my new train set. What has that got to do with this question?... This.... I have a number of transformers and would like to experiement using then at a higher frequency....let say 500 hz and / or higher..... Would they still work?...I am assuming so... Should not be a problem. Designed for 25 Hz operation, they have a lot more iron in the core than those for 50/60 Hz. That means they are HEAVY. [it's a mechanical mounting problem only] Would they run cooler?.... Not any more than audio amplifier power output transformers at the same wattage. Could anyone foresee any negative effects?.... Other than physical mounting places having to be much more sturdy, no problems at all. Aerospace electronics went to 400 Hz (and higher "wild" supply frequencies) some time ago to save WEIGHT. For the same power handling capability, the core size could be smaller for a given core flux desnity in comparison to 60 Hz. You WILL get heating and inordinate core losses and loss of efficiency of power transfer in trying to use a 400 Hz transformer at 60 Hz. You will NOT have any of those problems on getting a lower- frequency transformer to work at a higher frequency. For common transformer iron laminations, the upper end of frequency response...where all the effects others were talking about, would be above, perhaps, 5 KHz to 10 KHz. Those other effects would only begin to show up at that limit frequency, getting worse at higher frequencies. In the old vacuum tube "Hi-Fi" music amplifers, output transformers needed a BIG core cross section to reach down to 30 Hz. The upper end of response was determined primarily by the distributed capacitance of the winding with the most turns, secondarily by the iron alloy of the core. Mutual inductance effects didn't much come into play - regardless of what some instructors talked about in classes to illustrate "points" about mutual inductance. :-) Len Anderson retired (from regular hours) electronic engineer person |
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