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Transformer Mounting


Paul Z.
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Browsing through an energy forum last week, some know-it-all claimed that any metal objects in the vicinity of the transformer can affect its internal field.  I have always suspected as such, but had no facts to back it up.

Up until this point, all my transformers were mounted on HPDE legs (usually three of them), with high temp nylon straps, as shown in the picture below.  The only metal is the screws that hold the legs down -- and even those are recessed about 3/8-inch.

Now, my question is, is all this insulation really unnecessary?  Should I just be using steel straps like Power Jack?

Obviously, I would still elevate the transformer, as shown, for better airflow...only with metal brackets.  This enclosure is blower vented, so the transformer stays pretty cool regardless.

 

transformer.thumb.jpg.a46ff7892cb3b679b37ac50f4e2c57b7.jpg

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3 minutes ago, Paul Z. said:

some know-it-all claimed that any metal objects in the vicinity of the transformer can affect its internal field.  I have always suspected as such, but had no facts to back it up.

I mean, if you dig far enough, there will probably be some correlation between the orbit of Saturn and the purity of the transformer's AC output...

You can test and experiment with different methods, and check them with the hum of the transformer, the no load current, quality of the AC output, efficiency--but likely none of it will matter ;-).  Whatever is safest/best for your needs will probably be fine.

The only thing to watch out for is accidentally making a full loop around the transformer core with a magnetically permeable material.  The PJ brackets have a plastic insulator at the bottom for this very reason--without it, you'll get 300-400 amps at 1v (or whatever the turns/volt is on the transformer in question) running through the material, which will cause high idle current...and a fire hazard as the metal heats up.

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That's a nice cabinet you have!  I like your foam? mounting blocks too.  I ended up using rubber wedges (4) cut from a rubber buffing wheel.  Didn't bother tying it down as you did (probably smarter to tie it down, but no earthquakes here).  Figured trans was heavy enough not to move.  Raising the trans up greatly improved airflow and therefore transformer cooling efficiency for me.  Worth the effort.

My older model transformers all have a plastic-coated metal (aluminum? sheet metal?) 'sleeve' around them, which I always assumed was to contain the magnetic field.  This is on 2 and 3 transformer model powerjacks,  to limit interference with the other transformers?  Just guessing but seems reasonable.  Necessary?  Who knows.

IMG_2743.JPG

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34 minutes ago, dochubert said:

What material is it made of?  High temp plastic?

Its ABS so rated to melting point 230C which is about 440F so rated well beyond the insulation on the wire to the transformer.  I kept the rubber pad under coil just to make sure that vibration doesn't cause any issues.  Rubber melts at about 180C 350F so guess rubber pad is the weak point but if the coil ever gets that hot I would hope that the inverter would have shut down by then.

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On 4/29/2021 at 10:17 PM, dochubert said:

I think you've got a winner there!  I've never had an issue with the rubber pads or the rubber blocks I've been using.  I consider a transformer "running too hot" if it reaches 50c so should be no issues with your cooling plate with typical loads.

Nice job!

My poor MSB units hit 45°C daily. That is 113°F. As for the plastic temps that  AquaticsLive   quotes, that is strange as the printer prints both the ABS and PLA at 180°C except for the PLA Carbon Fiber which prints at 200°C. You can tell the difference in PLA and ABS after printing as the ABS shrinks a lot more. The PLA Carbon Fiber needs the higher temp to flow better.

 

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On 4/29/2021 at 7:24 PM, AquaticsLive said:

This is my 3D printed cooling plate, huge improvement.  Similar idea as Paul's.  If anyone wants the stl file let me know.

Cooling.jpg

Yes please. I think that would be perfect for having one on top and bottom to help cool a transformer.

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42 minutes ago, Waterman said:

My poor MSB units hit 45°C daily. That is 113°F.

Ambient temp in a hot garage/shed.  I wouldn't be concerned until units exceed 150-160F internal.  Default GS settings don't reach full fan speed until 136F anyhow...

To transfer heat, a temperature difference is required...thermodynamics I guess.

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1 minute ago, Sid Genetry Solar said:

Ambient temp in a hot garage/shed.  I wouldn't be concerned until units exceed 150-160F internal.  Default GS settings don't reach full fan speed until 136F anyhow...

To transfer heat, a temperature difference is required...thermodynamics I guess.

Sad part is, mine is open to air flow by design. And still gets that hot.

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On 5/3/2021 at 7:35 AM, Waterman said:

You can tell the difference in PLA and ABS after printing as the ABS shrinks a lot more. The PLA Carbon Fiber needs the higher temp to flow better.

As far as temperature resistance my experience has been normal ABS holds up a bit better than PLA over time  Parts that I have made with PLA tend to get brittle after a few years.  I don't want to get in to the arguments though whatever works better for you is the best.

I haven't used PLA Carbon fiber one I will give a shot sometime. 

My battery bank and inverter is inside an ambulance that sees some very rough roads and its all about how much shock and vibration things can take.  I have solar panels mounted with 3D printed mounts that have been up there since 2016 on the roof taking highway speeds and the sun.  I just swapped out a bracket this winter just because I was a bit worried and still just as solid as I made it.  I think it comes down to the engineering behind making something taking the in to account the advantages of each each material. 

I do think we may end up with a 3D printer thread in the future though would like to share projects.  This is my current printer I designed and built it myself inside of a 48" server cabinet can print some pretty large items it is a fully heated cabinet.  I also have a cutting head which I can do some CNC with phenolic, super messy so don't like doing that unless I really need to. 

  IMG_20210504_200138118.thumb.jpg.1fb947d3e839b7efe8aab063b6c9ee31.jpg

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1 minute ago, AquaticsLive said:

As far as temperature resistance my experience has been normal ABS holds up a bit better than PLA over time  Parts that I have made with PLA tend to get brittle after a few years.  I don't want to get in to the arguments though whatever works better for you is the best.

 

 

No argument on the ABS being stronger, you just have to plan for the shrinkage.

And nice unit.

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