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Genetry Solar 12,000 watt prototype unboxing live


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11 hours ago, dochubert said:

Do you know what the kva rating is for that transformer?

Haha.  I wrote the winding specification right here on my laptop...wire diameter, number of parallel strands, number of turns, location of the winding terminations...this is no "off-the-shelf transformer."  It's 100% custom just for Genetry Solar, based on Genetry Solar specifications.

The windings are design rated for 12kw continuous.  The only unknown is the temperature rise from the core; that's what we'll determine when it's load tested.  But as large as the core is, I do not expect this to be a problem.

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Just was thinking Sid.  Why can L1 and L2 be separet cores?  Have them sideways instead of the normal way and have fans blowing directly through the cores.  Seem like if l1 and l2 wasn't together it would help on the heat problems. and uhm, why round?  couldn't it be square, or shape like a pillar.  I might be missing something, is it cause of the magnetic field.  Since far as I know there isn't a magnet in the center of these corils.

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OK, transformer basics...

The heat is generated by losses, of the core and the windings on the core.  In the case of a stock PJ inverter, the windings are severely undersized, causing them to generate a huge amount of heat at high load.  Separating this waste heat across 2 cores simply gives you more area to dissipate the heat, but it does not reduce the heat.

If you separate the L1 and L2 secondary windings to separate cores, now you need two primary windings as well.  If the windings and core are mathematically sized for this difference, the total wire and core cross section will remain the same--however, you've created twice as much work required to manufacture the inverter.  And the heat problem will remain the same, due to the inadequate winding specification.

Why is the transformer round?  Most other low-frequency inverters use a square-frame transformer, characterized by (comparatively) very high idle currents, and reduced efficiency.  The round toroidial transformer is difficult to mount, but it is significantly more efficient, with much lower idle current.  I haven't studied this sort of thing to explain why, I just appreciate that it is ;-).

You are correct, there is no "magnet" in the center of the toroid cores, however when they're running, there is an extremely strong magnetic field present in (and around) the cores due to the electromagnetic principle of wire wrapped around a magnetically permeable material.

 

I personally mounted a "9kw" PJ AS-5 transformer sideways, with a 200CFM fan blowing directly through the center of the core.  Still overloaded at a 3kw load.

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Thanks Sid for the lesson.  I'm always learning new things.  I got into this hobby about three years ago, and learning how things work from eletrical to makeing batteries.  Kind of fun.  Too bad you can't incorporate water cooling into a coil, sort of using a heat pipe design with prefilled water, seem you could make a thicker wire with water cooling and use less wire to get the same results.

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30 minutes ago, The Blind Wolf said:

Too bad you can't incorporate water cooling into a coil, sort of using a heat pipe design with prefilled water, seem you could make a thicker wire with water cooling and use less wire to get the same results.

Not like hollow copper pipe hasn't been used before on huge transformers for just this reason ;-).  Of course, by the time you need water cooling, there's significant losses involved...so it's easier just to calculate the winding specification to carry the desired load.

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Quote

I personally mounted a "9kw" PJ AS-5 transformer sideways, with a 200CFM fan blowing directly through the center of the core.  Still overloaded at a 3kw load.

There's got to be something wrong with that transformer!  My old 3 transformer pj (3 AS2 xfmrs in parallel) can do 4-5kw for hours with good fan control.  It'll do 6kw for a short while...

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Sean said the same after I told him about it.  Only thing I can guess is perhaps the core...but the windings were good.  Actually took that one apart, paralleled all 3 tiny strands of wire (1 on one phase, 2 strands on the other) for one phase, added a whole winding for the second phase, and put the primary back on...don't recommend that to anyone for an afternoon project...but it seems to run cooler.  It was designed before PJ started making transformers in-house, and had copper wire.

A friend provided me a hand-wound transformer that runs like a dream in comparison...ever since installing it, my 200CFM fans have NEVER reached full speed.  Come to think of it, they've never reached 50% speed, either...

Would have to say that the 3 AS2s running 5kw is about 1.66kw each.  As PJ can't run less than 1 strand of wire for a coil, that sounds about right. 

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2 hours ago, Sid Genetry Solar said:

Sean said the same after I told him about it.  Only thing I can guess is perhaps the core...but the windings were good.  Actually took that one apart, paralleled all 3 tiny strands of wire (1 on one phase, 2 strands on the other) for one phase, added a whole winding for the second phase, and put the primary back on...don't recommend that to anyone for an afternoon project...but it seems to run cooler.  It was designed before PJ started making transformers in-house, and had copper wire.

A friend provided me a hand-wound transformer that runs like a dream in comparison...ever since installing it, my 200CFM fans have NEVER reached full speed.  Come to think of it, they've never reached 50% speed, either...

Would have to say that the 3 AS2s running 5kw is about 1.66kw each.  As PJ can't run less than 1 strand of wire for a coil, that sounds about right. 

A lot of people down under and in England have been stripping toroidal transformers and rewinding them to get what they want. And they work. Sounds like your friend did the same for you.

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