about interwinding capacitence... / High Voltage / Forums

Forums

4hv.org :: Forums :: High Voltage

« Previous topic | Next topic »

about interwinding capacitence...

previous 1 2 3 next

Move Thread

LAN_403

Patrick

Tue Mar 23 2010, 07:30PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Mattski i remember now.

Suliaman yeah i realise that.

Steve McConnor thanks for that delete, i dont know how that haappened maybe i had two windows open at the sam time, or i had a network hiccup. thanks for the links too, i am a regular visitor to Steve Wards site which i referenc often, he is an ace coiler, in my book.

IntraWinding

Wed Mar 24 2010, 01:33AM

Registered Member #2261 Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581

I had all sorts of hassle from intrawinding capacitance years ago when I was trying to build a HeNe laser power supply based on a switch mode controller IC, which I guess was the wrong approach, but I didn't have much to go on at the time - certainly nothing as great as 4HV

Anyway, hence the name... Oh, and the number of HT secondary coils I wound back then! Good luck with your efforts.

McCluskyCustom

Wed Mar 24 2010, 02:09AM

Registered Member #2538 Joined: Sat Dec 12 2009, 06:56AM
Location: San Luis Obispo, CA, USA
Posts: 10

The technique Sulaiman pointed out above reduces the distributed capacitance by 25%, which is significant considering the potential circulating currents. This figure is calculated and comes from the paper I mentioned previously.

The capacitance doesn't necessarily limit your upper frequency, esp if you are driving it with a sine wave (or some sort of resonance). What it does do is increase circulating currents. Circulating currents sap power and thus output voltage, but more importantly, can overheat the secondary. I^2*R losses in thin wire, and with many turns packed into layers in a small space, heat has trouble escaping, and *poof* smoke. Increasing AWG of your wire will reduce the power loss in the secondary assuming the capacitance is constant. But often smaller wire allows fewer layers and thus less capacitance, yielding lower power losses, despite its higher resistance. As with everything, balance.

Patrick

Wed Mar 24 2010, 03:23AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

yikes....i need to think about all this some more...

Sulaiman

Thu Mar 25 2010, 06:24PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141

The technique that I mentioned also reduces inter-layer voltage stress by 50%
- very useful.

Patrick

Fri Mar 26 2010, 12:12AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

yeah suliaman i realize that, and uzzors mentions that as a significant advantage.

IntraWinding

Fri Mar 26 2010, 02:38PM

Registered Member #2261 Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581

What's the best way to run the wire back so that each layer starts at the same end? Do you need to give it it's own insulated layer in the winding?

Patrick

Sat Mar 27 2010, 06:51AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

yes IntraWinding i use a 0.004" layer of overheadtransparency for that run back strand.

i dont know what the right layer+taper rate is i need~625 turns on my secondary im going to try a layout of

140+120+100+80+60+50+40+30

which is 620 turns in those 8 layers. with the 140 turn layer being
near ground, and the 30 turn layer being the highest voltage one. I believe this is what Steve Ward does for his CCPS project. he used 18 mils of PE between layers, i will use 31 mils of polyester (overhead transparencies), vinyl-nylon (bill board signage), paper (computer paper), and oil (veggie). between each layer of wire which should be good for mucho kV (I belive i have characterized this to 21kV). but capacitence still worries me. I will PM Steve Ward soon. oh, also the oil is vaccum drawn at 100 microns of mecury, for a total cycle and profile of about 3-4 hours of high vacuum.

-Patrick

IntraWinding

Sat Mar 27 2010, 11:25AM

Registered Member #2261 Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581

Apart from spacing the windings, I also tried increasing the distance between winding layers. After a layer of insulation I added a couple of layers of thick self adhesive Glass Fibre tape and another layer of insulation.

Here's that paper freely available if anyone needs it:

Using Transformer Parasitics for Resonant Converters â€“
A Review of the Calculation of the Stray Capacitance of Transformers

Patrick

Sat Mar 27 2010, 05:12PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

whoa! that was a pdf i really needed, thanks IntraWinding!

i still dont know why Steve Ward thinks my transformer will have to much impedeance, i sent a PM , so far even with capacitence it looks like it should work. Or so the math suggests, though until one builds it one cannot make great claims.

-Patrick

previous 1 2 3 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob