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Vacuum pump for high voltage transformer potting

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joeqsmith:

--- Quote from: xzswq21 on August 11, 2021, 07:05:24 pm ---Do you know any small size and reliable vacuum pumps and vacuum chambers?

--- End quote ---
Sorry but I have no idea what country you are even in.

NiHaoMike:

--- Quote from: langwadt on August 11, 2021, 11:08:00 pm ---if you have plenty of water (or a water pump) a water aspirator?

--- End quote ---
The only thing venturi type vacuum pumps are good for is applications where they're likely to suck contaminants that would damage most pumps. It's not at all difficult to find a mechanical pump that can pull lower.

xzswq21:
What do you think about the Leybold TRIVAC series (but used not a new)? For example Trivac D 2.5 E? Thanks

geggi1:
Check on youtube.
You will find several videos on how to make a vacuum chamber with a fridge compressor and a pressure cooker.
Mos of the time these builds are used for potting and is probably sufficient for your use.

jonpaul:
Bonjour a tous: Just now  reading the OP post by  xzswq21

in 1980s and 1990 we made many potted HVPS with transformers for 12 KV aviation PSU. ~ 10,000 pcs were made over the years.

1/ The potting compound is critical esp for fill and cure chemistry as well as creation of internal mechanical stress during cure.

2/ Generally a two part heat cure epoxy/silica/filler is used.

3/ The device used is a vacuum oven, which are available from industrial equipment suppliers in all sizes. Check epay for used ones.

4/ Homebuilt vacuum is possible but somewhat risky from safety and yield. Consult a few vacuum technique textbooks, many are available.

5/ We pulled ~ 1mm Hg and kept the pumps running for the entire cure cycle, many hours or overnight.

6/ After cure, an annealing cycle is used to relieve internal stresses.

7/ Stress can crack the ferrite and damage insulation and other parts. Poor Yield kills profit and results in useless bricked units. We had 50% initially and 95% after a year of process and compund improvement.

8/ Stress is proportional to potting shell dimensions, our parts were ~ 1x1x3". Larger shells may have worse stress.

I hope this info is useful to the OP and others.

Just the ramblings of an old retired EE.....

Bon Chance!

Jon


 

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