high-voltage transformer

W

Winfield Hill

Guest
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 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.
Click to expand...

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.
Click to expand...

Test it to breakdown!

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
 
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
Click to expand...

Isn't that wire insulation only good for 4kV? I guess 11kV isn't enough to cause breakdown between windings.

--
Thanks,
- Win
Click to expand...
 
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.
Click to expand...

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
 
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?
Click to expand...

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!
Click to expand...

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
 
X-ray low power tube power supply

http://ixbt.photo/photo/358797/30781Lv6MstoAez/aAL2LDV3Bs/1315772.jpg
 
On 2019-10-31 11:48, Winfield Hill wrote:
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.
Click to expand...

If by "snapped" you mean it started arcing then it is definitely not
suitable for 6kV working voltage. There is a huge difference between
working voltage and max dielectric withstand. Easily one order of magnitude.

Damage introduced by HV testing (such as hipot) is cumulative which is
why we are time-limited in medical for such tests.

If I needed a LV supply up on a HV rail I'd look at series resonant
structured with a massive isolation barrier. Simular to how electric
toothbrushes such as Philips Sonicare are charged.

--
Regards, Joerg

http://www.analogconsultants.com/
 
Joerg wrote...
If by "snapped" you mean it started arcing ...
Click to expand...

The arc was external to the transformer, across
the thin exposed pins, acting as sharp points.
I can harden them in the final product.

If I needed a LV supply up on a HV rail I'd look at
series resonant structured with a massive isolation
barrier.
Click to expand...

I made a serious HV transformer, similar to a TV
flyback, and used it at 20kV, but I'm looking for
a more simple approach. I think it'll work out OK.


--
Thanks,
- Win
 
On 2019-10-31 15:01, Winfield Hill wrote:
Joerg wrote...

If by "snapped" you mean it started arcing ...

The arc was external to the transformer, across
the thin exposed pins, acting as sharp points.
I can harden them in the final product.

If I needed a LV supply up on a HV rail I'd look at
series resonant structured with a massive isolation
barrier.

I made a serious HV transformer, similar to a TV
flyback, and used it at 20kV, but I'm looking for
a more simple approach. I think it'll work out OK.
Click to expand...

Just be careful. Sometimes HV stuff will initially work, for a while.
Then the barrier gradually breaks down until there is a loud bang. Or
you arrive at your lab and wonder why there are three fire trucks :)

--
Regards, Joerg

http://www.analogconsultants.com/
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top