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high-voltage transformer

Started by Winfield Hill October 31, 2019
 My 1:1 high-voltage transformer is coming along well.
 This is to make 5V, 12V, or whatever at high voltages.
 I'll be using it at 6kV, but it's passing tests at 9kV,
 and I'll do a weekend at 11kV before pronouncing it OK.

 The transformer is a small 50-cent common-mode choke,
 TAIYO YUDEN p/n TLF9UA102W0R8K1, footprint only 11x17mm.
 The pins are spaced 8mm.  We potted it with vacuum air
 removal, Dow Corning Sylgard-184, otherwise called PDMS.
 Testing with +5kV and -4kV, to avoid corona discharge.

https://www.dropbox.com/s/xtuzkei0xg8huhg/TLF9UA_potted.jpg?dl=1


-- 
 Thanks,
    - Win
On Thursday, October 31, 2019 at 9:25:14 AM UTC-4, Winfield Hill wrote:
> My 1:1 high-voltage transformer is coming along well. > This is to make 5V, 12V, or whatever at high voltages. > I'll be using it at 6kV, but it's passing tests at 9kV, > and I'll do a weekend at 11kV before pronouncing it OK. > > The transformer is a small 50-cent common-mode choke, > TAIYO YUDEN p/n TLF9UA102W0R8K1, footprint only 11x17mm. > The pins are spaced 8mm. We potted it with vacuum air > removal, Dow Corning Sylgard-184, otherwise called PDMS. > Testing with +5kV and -4kV, to avoid corona discharge. > > https://www.dropbox.com/s/xtuzkei0xg8huhg/TLF9UA_potted.jpg?dl=1
Isn't that wire insulation only good for 4kV? I guess 11kV isn't enough to cause breakdown between windings.
> > > -- > Thanks, > - Win
bloggs.fredbloggs.fred@gmail.com wrote...
> > On October 31, 2019, Winfield Hill wrote: >> >> My 1:1 high-voltage transformer is coming along well. >> This is to make 5V, 12V, or whatever at high voltages. >> I'll be using it at 6kV, but it's passing tests at 9kV, >> and I'll do a weekend at 11kV before pronouncing it OK. >> >> The transformer is a small 50-cent common-mode choke, >> TAIYO YUDEN p/n TLF9UA102W0R8K1, footprint only 11x17mm. >> The pins are spaced 8mm. We potted it with vacuum air >> removal, Dow Corning Sylgard-184, otherwise called PDMS. >> Testing with +5kV and -4kV, to avoid corona discharge. >> >> https://www.dropbox.com/s/xtuzkei0xg8huhg/TLF9UA_potted.jpg?dl=1 > > Isn't that wire insulation only good for 4kV? I guess > 11kV isn't enough to cause breakdown between windings.
The primary is near ground, and the secondary at HV. The coil voltages are low. I'm relying on the plastic bobbin for winding insulation from the ferrite core. The Sylgard protects all the other paths. The PCB will have a slot between coil sections, and it'll get a coat of urethane. -- Thanks, - Win
On Thursday, October 31, 2019 at 6:25:14 AM UTC-7, Winfield Hill wrote:
> My 1:1 high-voltage transformer is coming along well.
> The transformer is a small 50-cent common-mode choke, > TAIYO YUDEN p/n TLF9UA102W0R8K1, footprint only 11x17mm.
Common-mode chokes are often lossy; does your test include a thermometer? And, are you testing at low-load as well as high-load? Magnetization modulation in the core means that low-output-current is where the core losses are dominant. High-output-current testing will find the copper resistive losses to be the main effect.
On 31 Oct 2019 10:08:49 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

>bloggs.fredbloggs.fred@gmail.com wrote... >> >> On October 31, 2019, Winfield Hill wrote: >>> >>> My 1:1 high-voltage transformer is coming along well. >>> This is to make 5V, 12V, or whatever at high voltages. >>> I'll be using it at 6kV, but it's passing tests at 9kV, >>> and I'll do a weekend at 11kV before pronouncing it OK. >>> >>> The transformer is a small 50-cent common-mode choke, >>> TAIYO YUDEN p/n TLF9UA102W0R8K1, footprint only 11x17mm. >>> The pins are spaced 8mm. We potted it with vacuum air >>> removal, Dow Corning Sylgard-184, otherwise called PDMS. >>> Testing with +5kV and -4kV, to avoid corona discharge. >>> >>> https://www.dropbox.com/s/xtuzkei0xg8huhg/TLF9UA_potted.jpg?dl=1 >> >> Isn't that wire insulation only good for 4kV? I guess >> 11kV isn't enough to cause breakdown between windings. > > The primary is near ground, and the secondary at HV. > The coil voltages are low. I'm relying on the plastic > bobbin for winding insulation from the ferrite core. > The Sylgard protects all the other paths. The PCB will > have a slot between coil sections, and it'll get a coat > of urethane.
Test it to breakdown! -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
whit3rd wrote...
> >On Thursday, October 31, 2019 at 6:25:14 AM UTC-7, Winfield Hill wrote: >> My 1:1 high-voltage transformer is coming along well. > >> The transformer is a small 50-cent common-mode choke, >> TAIYO YUDEN p/n TLF9UA102W0R8K1, footprint only 11x17mm. > > Common-mode chokes are often lossy; does your test > include a thermometer?
We only need 0.5 watt, the losses are a fraction of that. The primary goal was to find a commercial part, with excess bobbin plastic, suitable to further HV hardening. -- Thanks, - Win
John Larkin wrote...
> >On 31 Oct 2019 10:08:49 -0700, Winfield Hill <winfieldhill@yahoo.com> >wrote: > >>bloggs.fredbloggs.fred@gmail.com wrote... >>> >>> On October 31, 2019, Winfield Hill wrote: >>>> >>>> My 1:1 high-voltage transformer is coming along well. >>>> This is to make 5V, 12V, or whatever at high voltages. >>>> I'll be using it at 6kV, but it's passing tests at 9kV, >>>> and I'll do a weekend at 11kV before pronouncing it OK. >>>> >>>> The transformer is a small 50-cent common-mode choke, >>>> TAIYO YUDEN p/n TLF9UA102W0R8K1, footprint only 11x17mm. >>>> The pins are spaced 8mm. We potted it with vacuum air >>>> removal, Dow Corning Sylgard-184, otherwise called PDMS. >>>> Testing with +5kV and -4kV, to avoid corona discharge. >>>> >>>> https://www.dropbox.com/s/xtuzkei0xg8huhg/TLF9UA_potted.jpg?dl=1 >>> >>> Isn't that wire insulation only good for 4kV? I guess >>> 11kV isn't enough to cause breakdown between windings. >> >> The primary is near ground, and the secondary at HV. >> The coil voltages are low. I'm relying on the plastic >> bobbin for winding insulation from the ferrite core. >> The Sylgard protects all the other paths. The PCB will >> have a slot between coil sections, and it'll get a coat >> of urethane. > > Test it to breakdown!
I was worried about the 8mm pin-to-pin clearance, and the inadequate hardening of my setup, compared to the end-use installation. I added teflon sleeves to the exposed pins. Then I started increasing the voltage towards 11kV. But it snapped anyway, at 10kV. Everything is still fine, zero uA leakage, but I'm going to finish with a four day soak test at 8.5kV, to convince myself it'll be fine for use at 6kV. The scheme should be good to higher voltages, with a choke having more pin clearance, like my original part's 12mm. -- Thanks, - Win
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