HV insulation test

[Winfield Hill]

Panasonic ELF-21C0006A common-mode choke, with
insulation rating 2kV / 1min. Has two windings
on plastic bobbins, on opposite ferrite-core
legs. Digi-Key Part Number: PLK1296-ND

https://www.dropbox.com/s/wybkrot1xz6s33a/ELF-21C023A.jpg?dl=1

Candidate for 1:1 HV transformer, with 5 to 10kV
pri-sec insulation, after vacuum potting, with
Dow Corning Sylgard 184, rated at 12kV/mm.

https://www.dropbox.com/s/t0gg0rmgcnq2mbh/6kV-transformer_Sylgard-184.jpg?dl=1

HV insulation test, with an SRS PS350 5kV supply.
SHV connector with 2m of RG-58 coax and a pair
of alligator-clips. No coax leakage at 4kV, but
observe 4 to 5uA at 5kV. No additional leakage
with the potted transformer connected. Over the
first 20min, total leakage declines to 0uA, but
observe occasional jumps to 5uA, decaying in a
few seconds. Go to gym for 90 minutes. After
returning, leakage current is continuously zero,
and is still zero, for this report at six hours.


--
Thanks,
- Win

 

Winfield Hill <winfieldhill@yahoo.com> wrote in
news:qnu0rs02ks2@drn.newsguy.com:

Panasonic ELF-21C0006A common-mode choke, with
insulation rating 2kV / 1min. Has two windings
on plastic bobbins, on opposite ferrite-core
legs. Digi-Key Part Number: PLK1296-ND

https://www.dropbox.com/s/wybkrot1xz6s33a/ELF-21C023A.jpg?dl=1

Candidate for 1:1 HV transformer, with 5 to 10kV
pri-sec insulation, after vacuum potting, with
Dow Corning Sylgard 184, rated at 12kV/mm.

https://www.dropbox.com/s/t0gg0rmgcnq2mbh/6kV-transformer_Sylgard-1
84.jpg?dl=1

HV insulation test, with an SRS PS350 5kV supply.
SHV connector with 2m of RG-58 coax and a pair
of alligator-clips. No coax leakage at 4kV, but
observe 4 to 5uA at 5kV. No additional leakage
with the potted transformer connected. Over the
first 20min, total leakage declines to 0uA, but
observe occasional jumps to 5uA, decaying in a
few seconds. Go to gym for 90 minutes. After
returning, leakage current is continuously zero,
and is still zero, for this report at six hours.


Looks like it is partially potted in hard "Stycast" epoxy.

You should encapsulate the rest (windings) as best you can.


Ideally Vacuum encapsulate it.

However, you can simply spray on some varnish and pull a partial
vac on it and it will soak in and possibly cover the leak site.


https://www.electro-wind.com/dolph-spray-ac-46-anti-fungal-clear-air-
drying-varnish-155-c-clear-aerosal-spray-can-425-g.html

 

On 12 Oct 2019 19:06:52 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

Panasonic ELF-21C0006A common-mode choke, with
insulation rating 2kV / 1min. Has two windings
on plastic bobbins, on opposite ferrite-core
legs. Digi-Key Part Number: PLK1296-ND

https://www.dropbox.com/s/wybkrot1xz6s33a/ELF-21C023A.jpg?dl=1

Candidate for 1:1 HV transformer, with 5 to 10kV
pri-sec insulation, after vacuum potting, with
Dow Corning Sylgard 184, rated at 12kV/mm.

https://www.dropbox.com/s/t0gg0rmgcnq2mbh/6kV-transformer_Sylgard-184.jpg?dl=1

HV insulation test, with an SRS PS350 5kV supply.
SHV connector with 2m of RG-58 coax and a pair
of alligator-clips. No coax leakage at 4kV, but
observe 4 to 5uA at 5kV. No additional leakage
with the potted transformer connected. Over the
first 20min, total leakage declines to 0uA, but
observe occasional jumps to 5uA, decaying in a
few seconds. Go to gym for 90 minutes. After
returning, leakage current is continuously zero,
and is still zero, for this report at six hours.

Crank the voltage up until it arcs.



--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[Tim Williams]

Doesn't even have to be that fancy. I hi-potted a one like this,
https://www.digikey.com/product-detail/en/taiyo-yuden/TLF9UA102W0R8K1/587-2788-ND/2573875
breaking down at ~10kV. Sparked over the middle divider. ("Like" as in, it
was actually a Panasonic version, now obsolete; this one looks very
similar.)

Should have much lower leakage than the kind you've shown, so you aren't
forced into a resonant type supply.

I wonder at what point the bobbin breaks down (through the divider, or to
the core and back).

Can always cascade things for more voltage standoff...

Have you looked at planar (PCB based) transformers? Should be good for a
lot of voltage (you can get the board basically as thick as you like), and
low leakage. May be on the expensive side; definitely slow to prototype.

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/

"Winfield Hill" <winfieldhill@yahoo.com> wrote in message
news:qnu0rs02ks2@drn.newsguy.com...

Panasonic ELF-21C0006A common-mode choke, with
insulation rating 2kV / 1min. Has two windings
on plastic bobbins, on opposite ferrite-core
legs. Digi-Key Part Number: PLK1296-ND

https://www.dropbox.com/s/wybkrot1xz6s33a/ELF-21C023A.jpg?dl=1

Candidate for 1:1 HV transformer, with 5 to 10kV
pri-sec insulation, after vacuum potting, with
Dow Corning Sylgard 184, rated at 12kV/mm.

https://www.dropbox.com/s/t0gg0rmgcnq2mbh/6kV-transformer_Sylgard-184.jpg?dl=1

HV insulation test, with an SRS PS350 5kV supply.
SHV connector with 2m of RG-58 coax and a pair
of alligator-clips. No coax leakage at 4kV, but
observe 4 to 5uA at 5kV. No additional leakage
with the potted transformer connected. Over the
first 20min, total leakage declines to 0uA, but
observe occasional jumps to 5uA, decaying in a
few seconds. Go to gym for 90 minutes. After
returning, leakage current is continuously zero,
and is still zero, for this report at six hours.


--
Thanks,
- Win

 

[Martin Riddle]

On 12 Oct 2019 19:06:52 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

Panasonic ELF-21C0006A common-mode choke, with
insulation rating 2kV / 1min. Has two windings
on plastic bobbins, on opposite ferrite-core
legs. Digi-Key Part Number: PLK1296-ND

https://www.dropbox.com/s/wybkrot1xz6s33a/ELF-21C023A.jpg?dl=1

Candidate for 1:1 HV transformer, with 5 to 10kV
pri-sec insulation, after vacuum potting, with
Dow Corning Sylgard 184, rated at 12kV/mm.

https://www.dropbox.com/s/t0gg0rmgcnq2mbh/6kV-transformer_Sylgard-184.jpg?dl=1

HV insulation test, with an SRS PS350 5kV supply.
SHV connector with 2m of RG-58 coax and a pair
of alligator-clips. No coax leakage at 4kV, but
observe 4 to 5uA at 5kV. No additional leakage
with the potted transformer connected. Over the
first 20min, total leakage declines to 0uA, but
observe occasional jumps to 5uA, decaying in a
few seconds. Go to gym for 90 minutes. After
returning, leakage current is continuously zero,
and is still zero, for this report at six hours.

Could have been surface moisture or just organics (finger oils, lunch,
etc). You can also throw that into a oven and bake at ~85C to burn off
organics.

Cheers

 

[Winfield Hill]

DecadentLinuxUserNumeroUno@decadence.org wrote...

Winfield Hill wrote:

Panasonic ELF-21C0006A common-mode choke, with
insulation rating 2kV / 1min. Has two windings
on plastic bobbins, on opposite ferrite-core
legs. Digi-Key Part Number: PLK1296-ND

https://www.dropbox.com/s/wybkrot1xz6s33a/ELF-21C023A.jpg?dl=1

Candidate for 1:1 HV transformer, with 5 to 10kV
pri-sec insulation, after vacuum potting, with
Dow Corning Sylgard 184, rated at 12kV/mm.

https://www.dropbox.com/s/t0gg0rmgcnq2mbh/6kV-transformer_Sylgard-1
84.jpg?dl=1

Looks like it is partially potted in hard "Stycast" epoxy.
You should encapsulate the rest (windings) as best you can.
Ideally Vacuum encapsulate it.

The Sylgard 184 is transparent, so you don't see the
2mm of extra potting around the entire transformer.
After pouring, it was placed in a vacuum to set, and
then baked overnight. Dow Corning Sylgard 184 is a
flexible silicone elastomer, meant for HV insulation.

https://www.dropbox.com/s/po5numnm3le783a/Sylgard-184_ds.pdf?dl=1


--
Thanks,
- Win

 

[Michael Terrell]

On Sunday, October 13, 2019 at 9:59:51 AM UTC-4, Winfield Hill wrote:

jlarkin wrote...

Crank the voltage up until it arcs.

Then I'd have to throw it away. I finished
the SHV cable at the end of work Friday, and
took home a 5kV supply. Tuesday I'll push to
higher voltages, thinking of stopping at 10kV.

I need to rebuild the SHV cable, forgot to
flair the shield away from the RG-58/U center
dielectric, before soldering a ground wire.

Are you familiar with HV putty?

<https://www.newark.com/gc-electronics/10-8880/high-voltage-silicon-putty-1-25/dp/33K4548>

 

[Winfield Hill]

jlarkin@highlandsniptechnology.com wrote...

Crank the voltage up until it arcs.

Then I'd have to throw it away. I finished
the SHV cable at the end of work Friday, and
took home a 5kV supply. Tuesday I'll push to
higher voltages, thinking of stopping at 10kV.

I need to rebuild the SHV cable, forgot to
flair the shield away from the RG-58/U center
dielectric, before soldering a ground wire.


--
Thanks,
- Win

 

[Winfield Hill]

Tim Williams wrote...

Doesn't even have to be that fancy. I hi-potted a one like this,
https://www.digikey.com/product-detail/en/taiyo-yuden/TLF9UA102W0R8K1/587-2788-ND/2573875
breaking down at ~10kV. Sparked over the middle divider.

10kV sounds good, I'm thinking of 8kV tests for a few days.


--
Thanks,
- Win

 

Winfield Hill <winfieldhill@yahoo.com> wrote in news:qnvakb01i21
@drn.newsguy.com:

I need to rebuild the SHV cable, forgot to
flair the shield away from the RG-58/U center
dielectric, before soldering a ground wire.

We made ours in a way we called a "stab" termination.

The entire center, insulator and conductor is out about 6 full
inches on our 50kV RG-8 version.

On RG-58, I would have a stab of about 2 or 3 inches.

We used a PVC pipe and filled the thing with dielectric paste.

The 'stab' gets a big solder ball placed onto the node protrusion
(which should only be slightly less than the ball height). Down at
the bottom of the pipe, we epoxied the HV out of the supply inside
it. That makes the distance between those two nodes a couple inches
at least.

It is like one of those unmentionable appendages with the sheath
pulled back.

Connector GND
Coax
____________|-------| Stab
| |------------@
____________| |------------@
|-------| ^place solder ball here (in center
of stab)

Box Wall Entry
|
|
| PVC Pipe
____________|-------||__________________
| || XX
____________| ||________________XX <Epoxy at bottom
|-------||
|
|
|--Max Separation--|
| |

 

jlarkin@highlandsniptechnology.com wrote in
news:7qf6qehdu80qhhe45vr1bt4sh4p6icjemj@4ax.com:

On 13 Oct 2019 06:59:39 -0700, Winfield Hill
winfieldhill@yahoo.com
wrote:

jlarkin@highlandsniptechnology.com wrote...

Crank the voltage up until it arcs.

Then I'd have to throw it away. I finished
the SHV cable at the end of work Friday, and
took home a 5kV supply. Tuesday I'll push to
higher voltages, thinking of stopping at 10kV.

I need to rebuild the SHV cable, forgot to
flair the shield away from the RG-58/U center
dielectric, before soldering a ground wire.

I was thinking that you could make a HV transformer by

Winding a ferrite toroid with a few turns of well-insulated wire,
maybe HV wire on secondary only

Place Nomex™ transformer paper on the core center.

It is 715 V/mil dielectric strength.

Double strength transformer wire has more. Some makers go up to
quad strength.

But I found the ultimate HV wire...

<https://www.zeusinc.com/products/insulated-wire/peek-insulated-
wire/>


WOW! 500 degrees! 25kV!

or

Separating the halves of a pot core with a sheet of really good
insulator.

You could also make a capacitive or inductive coupler as a PC
board.
Maybe use unshielded surface-mount drum core inductors on opposite
sides.

 

[Winfield Hill]

DecadentLinuxUserNumeroUno@decadence.org wrote...

Winfield Hill <winfieldhill@yahoo.com> wrote:

I need to rebuild the SHV cable, forgot to
flair the shield away from the RG-58/U center
dielectric, before soldering a ground wire.

We made ours in a way we called a "stab" termination.

The entire center, insulator and conductor is out about
6 full inches on our 50kV RG-8 version.

On RG-58, I would have a stab of about 2 or 3 inches.

We used a PVC pipe and filled the thing with dielectric paste.

The 'stab' gets a big solder ball placed onto the node protrusion
(which should only be slightly less than the ball height). Down at
the bottom of the pipe, we epoxied the HV out of the supply inside
it. That makes the distance between those two nodes a couple inches
at least.

It is like one of those unmentionable appendages with the sheath
pulled back.

Connector GND
Coax
____________|-------| Stab
| |------------@
____________| |------------@
|-------| ^place solder ball here
(in center of stab)

Box Wall Entry
|
|
| PVC Pipe
____________|-------||__________________
| || XX
____________| ||________________XX <Epoxy at bottom
|-------||
|
|
|--Max Separation--|
| |

That's interesting, assuming I understand it. The issue
I was talking about is creating a high electric field on
an abrupt edge of the shield braid, which can cause the
dielectric to fail. Flairing the braid, and filling the
space with insulator (heat-shrink layers, etc.), before
doing any operations on it, avoids creating high E-fields.


--
Thanks,
- Win

 

[Martin Riddle]

On Sun, 13 Oct 2019 14:48:16 +0000 (UTC),
DecadentLinuxUserNumeroUno@decadence.org wrote:

DecadentLinuxUserNumeroUno@decadence.org wrote in
news:qnvcpr$19am$1@gioia.aioe.org:


Connector GND
Coax
____________|-------| Stab
| |------------@
____________| |------------@
|-------| ^place solder ball here (in
|center
of stab)

Box Wall Entry
|
|
| PVC Pipe
____________|-------||__________________
| || XX
____________| ||________________XX <Epoxy at bottom
|-------||
|
|
|--Max Separation--|
| |


It did not display right on my client.

They do make HV BNC connector.
<https://www.newark.com/kings/1065-2/rf-coaxial-10kv-high-voltage-plug/dp/17B5421>

But you also need the HV 58 cable, most are only good to 5kv.

Cheers

 

DecadentLinuxUserNumeroUno@decadence.org wrote in
news:qnvcpr$19am$1@gioia.aioe.org:

Connector GND
Coax
____________|-------| Stab
| |------------@
____________| |------------@
|-------| ^place solder ball here (in
|center
of stab)

Box Wall Entry
|
|
| PVC Pipe
____________|-------||__________________
| || XX
____________| ||________________XX <Epoxy at bottom
|-------||
|
|
|--Max Separation--|
| |


It did not display right on my client.

 

On 13 Oct 2019 06:59:39 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

jlarkin@highlandsniptechnology.com wrote...

Crank the voltage up until it arcs.

Then I'd have to throw it away. I finished
the SHV cable at the end of work Friday, and
took home a 5kV supply. Tuesday I'll push to
higher voltages, thinking of stopping at 10kV.

I need to rebuild the SHV cable, forgot to
flair the shield away from the RG-58/U center
dielectric, before soldering a ground wire.

I was thinking that you could make a HV transformer by

Winding a ferrite toroid with a few turns of well-insulated wire,
maybe HV wire on secondary only

or

Separating the halves of a pot core with a sheet of really good
insulator.

You could also make a capacitive or inductive coupler as a PC board.
Maybe use unshielded surface-mount drum core inductors on opposite
sides.



--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[Winfield Hill]

Michael Terrell wrote...

Are you familiar with HV putty?

https://www.newark.com/gc-electronics/10-8880/high-voltage-silicon-putty-1-25/dp/33K4548

No, I wasn't, thanks!!


--
Thanks,
- Win

 

Winfield Hill <winfieldhill@yahoo.com> wrote in news:qnvi6b01uq5
@drn.newsguy.com:

> https://www.zeusinc.com/products/insulated-wire/peek-insulated-wire/

https://www.zeusinc.com/wp-
content/uploads/2017/05/PEEK_Insulated_Wire_ZEUS.pdf

 

[Winfield Hill]

DecadentLinuxUserNumeroUno@decadence.org wrote...

But I found the ultimate HV wire...

https://www.zeusinc.com/products/insulated-wire/peek-insulated-wire/

WOW! 500 degrees! 25kV!

Which one was that, I couldn't find it.


--
Thanks,
- Win

 

DecadentLinuxUserNumeroUno@decadence.org wrote in news:qnvgc3$1pb6$1
@gioia.aioe.org:

jlarkin@highlandsniptechnology.com wrote in
news:7qf6qehdu80qhhe45vr1bt4sh4p6icjemj@4ax.com:

On 13 Oct 2019 06:59:39 -0700, Winfield Hill
winfieldhill@yahoo.com
wrote:

jlarkin@highlandsniptechnology.com wrote...

Crank the voltage up until it arcs.

Then I'd have to throw it away. I finished
the SHV cable at the end of work Friday, and
took home a 5kV supply. Tuesday I'll push to
higher voltages, thinking of stopping at 10kV.

I need to rebuild the SHV cable, forgot to
flair the shield away from the RG-58/U center
dielectric, before soldering a ground wire.

I was thinking that you could make a HV transformer by

Winding a ferrite toroid with a few turns of well-insulated wire,
maybe HV wire on secondary only

Place Nomex™ transformer paper on the core center.

It is 715 V/mil dielectric strength.

Double strength transformer wire has more. Some makers go up to
quad strength.

But I found the ultimate HV wire...

https://www.zeusinc.com/products/insulated-wire/peek-insulated-
wire/


WOW! 500 degrees! 25kV!


or

Separating the halves of a pot core with a sheet of really good
insulator.

Not good. That gap has efficiency costs.

You could also make a capacitive or inductive coupler as a PC
board.
Maybe use unshielded surface-mount drum core inductors on opposite
sides.

Two drums, same side, Nomex paper separator. Still need a good core
in there.

 

Winfield Hill <winfieldhill@yahoo.com> wrote in
news:qnvg6g01r3o@drn.newsguy.com:

DecadentLinuxUserNumeroUno@decadence.org wrote...

Winfield Hill <winfieldhill@yahoo.com> wrote:

I need to rebuild the SHV cable, forgot to
flair the shield away from the RG-58/U center
dielectric, before soldering a ground wire.

We made ours in a way we called a "stab" termination.

The entire center, insulator and conductor is out about
6 full inches on our 50kV RG-8 version.

On RG-58, I would have a stab of about 2 or 3 inches.

We used a PVC pipe and filled the thing with dielectric paste.

The 'stab' gets a big solder ball placed onto the node
protrusion
(which should only be slightly less than the ball height). Down
at the bottom of the pipe, we epoxied the HV out of the supply
inside it. That makes the distance between those two nodes a
couple inches at least.

It is like one of those unmentionable appendages with the
sheath
pulled back.

Connector GND
Coax
____________|-------| Stab
| |------------@
____________| |------------@
|-------| ^place solder ball here
(in center of stab)

Box Wall Entry
|
|
| PVC Pipe
____________|-------||__________________
| || XX
____________| ||________________XX <Epoxy at bottom
|-------||
|
|
|--Max Separation--|
| |


That's interesting, assuming I understand it. The issue
I was talking about is creating a high electric field on
an abrupt edge of the shield braid, which can cause the
dielectric to fail. Flairing the braid, and filling the
space with insulator (heat-shrink layers, etc.), before
doing any operations on it, avoids creating high E-fields.

Ahhh... We also placed HV shrink on things. You are averting
corona failure or a plain and simple insulation failure breach.
I see.

We hired an engineer from a competitor HV company once, and this
guy was really smart. He did a demo for us once while we were
developing a 50kV supply. We test in fluorinert bath and that is
like 460V/mil dielectric strength. We have an HV probe that can read
that voltage, so he immerses the output node in a corner of the bath
away from the circuit board, and then an HV probe tip can be put on
it. OK so far. Then, he takes about 4 feet of an old broomstick
handle, and runs an HV insulated ground wire up it to the tip where
he places a nail with the tip rounded off. Standing back from the
bath, as he approaches it with the tip, the entire bath started
shaking and as he entered the bath, the HV arc'd right through the
fluorinert to the nail. I know about gradient and such, so i knew it
would do it, I just didn't think it would jump that far through the
fluid, and we had never seen the dancing bath thing before either.
That was cool. THEN he changed the round tip nal for a nail with a
very sharp tip. Talk about far out! It started dancing from several
feet away, and a LOT as he approached the fluorinert pan, and WOW, it
jumped up through the fluorinert and air to the nail before he even
got to it. Thankfully, each of these demonstrations were also a test
of the supplies shut down features, so it was OK. Only a single SNAP
arc each time. But that high gradient, sharp nail show was COOL!