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Selfwound 50hz HV transformer

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vasil

Sun Feb 26 2006, 08:03PM

Registered Member #229 Joined: Tue Feb 21 2006, 07:33PM
Location: Romania
Posts: 506

It looks awsome, but it will work for long time in SGTC service? If not, a future VTTC project can have this tranformer...

Marko

Sun Feb 26 2006, 08:08PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Actually biggest problem is to get the core apart.
Usually 'EE' cores are used and glued heavily (for cheap transformers) so its pain to get them apart, and even more pain to get all back and secure, soometimes core is welded (no chance to rewind such transformer).

I found a small transformer consisting of 4 C - cores, and got it apart.
May be rewound for HV transformer and used to power nano-SGTCs...

'EI' cores are also good, thats like one reaching has.
Just be careful with saturation...

iRET

Sun Feb 26 2006, 08:18PM

Registered Member #258 Joined: Sun Feb 26 2006, 03:58PM
Location:
Posts: 21

Reaching:
This is really interesting!

to see homemade transformer working nicely. How warm or hot does the transformer gets for like 5-10 seconds of running time? Are you planning to hook it up to a SGTC like vasil described?

Reaching

Sun Feb 26 2006, 08:26PM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

yeah, the core saturated when i draw an arc, hence this incredible peak current. the humming in the video is due to the transformers gap. i sawed the weldingline off to get the core into two pieces. i have no welder, so i screwed the parts together.

the biggest problem i had with this transformer was the primary. i thought i can use the old one but the new primary part of the former was too small, so i got only half of the windings on it.
tommorow i want to rewind the primary with some thinner wire to get more inductance. the core can take 2kW before it saturates so i have to find a compromise.

then to Omicron, we dont need useless posts like this here. as others mentioned, i dont want to kill myself and i know what im doing.

on 230volt input without ballasting the primary gets hot after a few seconds of arc drawing. with 200volt input, everything gets slightly warm even when i run it for minutes. with a mot primary as my ballast, everything is fine for long time, maximum current draw of around 9-10A

iRET

Sun Feb 26 2006, 08:54PM

Registered Member #258 Joined: Sun Feb 26 2006, 03:58PM
Location:
Posts: 21

I had similar humming/ticking in my transformer core. But mine was a rod shape core formed with insulated 22awg wires. I soaked the whole thing in shellac and baked it slowly in oven, now it's as hard as a solid metal rod and no noise.

What kind of formula do you use to determine your core saturation level ?

Curious whether a incadescent bulb will served as a good ballasting.

Mike

Sun Feb 26 2006, 09:26PM

Registered Member #58 Joined: Thu Feb 09 2006, 05:40AM
Location: Tri-Cities, Washington, US
Posts: 317

Omicron, a lot of things people do on this board are most likely not safe and potentially lethal. However they know what they are doing, please don't crap on someone's success.

Anyways, awesome job Reaching. Those are very nice Arcs, somewhat near what 2 mots series'd look like, and you've done it from only one transformer!
Keep up the good work.

Reaching

Sun Feb 26 2006, 11:33PM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

yeah thanks.

i made a new primary with 2x0,5mm wire paralleled, around 500 turns. now it works fine for long time even on 230volt . while drawing an arc the current is near 6A. tommorow i want to experiment a bit with the primary turns. i want to unwind some windings until the core nearly saturates. with this technique i should be able to determine the most efficient primary setting. i want to go for 1,5kW or so.
with the current setting the transformer is silent, no buzzing or humming anymore

for beauty i wound a few layers isotape around the secondary,.

williamn

Mon Feb 27 2006, 12:39AM

Registered Member #55 Joined: Thu Feb 09 2006, 04:56AM
Location:
Posts: 149

Nice work Reaching! Not bad for your FIRST HV project

Do you think it could handle SGTC duty? It would make a great SGTC!

Kolas

Mon Feb 27 2006, 05:44AM

Registered Member #102 Joined: Thu Feb 09 2006, 08:15PM
Location: Raleigh, NC
Posts: 169

wow man, you got uber lucky!
i never could find a EI core like that, had to take a interlapped one apart
tee hee ill finish it up too
you've got me thinking about that thing agian
mine was goign to put out about 25kV

kolas

Reaching

Mon Feb 27 2006, 07:30AM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

yeah, i think, the transformer will work fine in a sgtc. the secondary is wound out of 0,3mm and got only warm at 2kw+ of input.it can withstand voltages above 6,5kV (tested) so i think it could do the job.

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