Author Topic: CORE FOR GDT AND CT  (Read 285 times)

Offline prabhatkumar

  • High Voltage Experimenter
  • **
  • Posts: 55
  • Karma: +0/-0
    • View Profile
CORE FOR GDT AND CT
« on: April 13, 2020, 03:02:15 PM »
Hey there everyone !! I had successfully made my first sstc and I am very pleased with it's performance . I know I am not making big arcs but then this was only a learning experience and I had it. But during the lockdown I was thinking to study more on drsstc and then also choose a core for the CT, GDT and capacitors for the mmc. I don't want to make like deadly arcs which are 4 feet long . My secondary is only 10 inches tall and has a diameter of around 4.2 inches. It has got 1400 turns. In real life ,I get a resonating frequency of 238.5 kHz. I will run the coil without the toroid.
So now for the main question , I was reading the forums for the core for GDT and CT , and found that mads replied that he uses this :
https://www.mouser.in/ProductDetail/EPCOS-TDK/B64290L674X830/?qs=sGAEpiMZZMt1hubY80%2Fs8DEvGx1xc7EcUsoMlWTaffs=
I also found that many people use this core:
https://in.element14.com/ferroxcube/tn32-19-13-3e25/ferrite-core-toroid-3e25/dp/3057008
I also found another toroid from ferroxcube which has a different coating ( epoxy ), compared to the above cores . These two cores have the same material 3e-25 . But strangely though the coated one has a bigger diameter and a higher Al value still being a little cheaper from the other . I don't know a lot about the cores so please enlighten me on this . I would prefer to order the cheaper one with epoxy coating as I could save like 4 usd on 20 pieces . Also will the high Al of 7.3 uH of this core be suitable for the gdt. Link for the 2nd ferroxcube core
https://in.element14.com/ferroxcube/tx36-23-15-3e25/ferrite-core-toroid-3e25/dp/3057021
Also sorry for the inconvenience as the prices are mentioned in INR and not in USD

As a standard rule of thumb ( as far as I know ) , the Al value should be above 5000 as mads has said in his drsstc design guide.
Now I could also source any of the above cores , the epcos being a little bit more expensive because it has got a slightly larger diameter, I am thinking on the ferroxocube one.
But while browsing I found a page on digikey where there is a large number of cores given with materials like N30, T-35, T-65 etc
Now I would go for the core diameter and the Al value mentioned aside each core , it is right or also do we need to look for the other properties of the core . If yes then please can someone share a link to a page or briefly explain the main difference between the types like T-35, T-38 etc . I will attach the link to that page which has the different cores given.
https://www.digikey.com/catalog/en/partgroup/toroid-core-type/23563
THANKS !!
« Last Edit: April 13, 2020, 03:12:42 PM by prabhatkumar »

Offline ritaismyconscience

  • High Voltage Technician
  • ***
  • Posts: 135
  • Karma: +3/-0
    • View Profile
Re: CORE FOR GDT AND CT
« Reply #1 on: April 14, 2020, 01:06:51 AM »
The second core is thicker (has more cross sectional area) so its inductance should be higher. Both of them should work though.

Offline prabhatkumar

  • High Voltage Experimenter
  • **
  • Posts: 55
  • Karma: +0/-0
    • View Profile
Re: CORE FOR GDT AND CT
« Reply #2 on: April 14, 2020, 04:59:40 AM »
Second one as in which core please mention the name ??

Offline klugesmith

  • High Voltage Technician
  • ***
  • Posts: 186
  • Karma: +5/-0
    • View Profile
Re: CORE FOR GDT AND CT
« Reply #3 on: April 14, 2020, 05:10:37 AM »
3E25 is one of many ferrite formula standards.  Others have different permeability and saturation flux density.  Permeability and high frequency loss are temperature-dependent functions of Bmax.

You can get the single-turn inductance directly from core dimensions and permeability. 
Those determine its magnetic reluctance (ampere turns per weber), whose inverse is the single turn inductance.  Might help to get an understanding how the core variables affect you.

For example, Let's consider that TN32-19-13-3E25. 

Put 1 turn of wire through it, carrying 1 ampere of current.
The toroid's effective length (of magnetic flux path) is 76 mm.
With 1 ampere of MMF spread uniformly along that path, the H value is I/l = 1.0/0.076 = 0.076 amperes/meter.  YOu can convert that to oersteds if you want.

The relative permability of 3E25 is given as 5500.  I'm no expert, but that seem like a nice high value for a ferrite.   Flux density in the core is B = H * u0 & u(relative), where u0 is always 4e-7*pi.  So B = 0.0909 teslas (909 gausses), well below saturation.

The toroid's effective area (of magnetic flux path) is given as 76.5 mm^2.
Total flux is the product of B and flux path area. 
In SI units, 0.091 * 7.65e-5 = 6.96e-6 webers = 6.96 uWb.

If the current were changing at 1 ampere per second, the flux would change at 6.96 uWb per second, automatically inducing 6.96 uV per turn.  Hence the inductance is 6.96 uH.
Verstehen Sie?

« Last Edit: April 14, 2020, 05:16:41 AM by klugesmith »

Offline davekni

  • High Voltage Engineer
  • ****
  • Posts: 378
  • Karma: +22/-0
  • Physicist, engineer (electronic), and hobbiest
    • View Profile
Re: CORE FOR GDT AND CT
« Reply #4 on: April 14, 2020, 06:45:19 AM »
"Second one as in which core please mention the name ??"  I think that refers to the TX36/23/15-3E25 core you listed as being a bit cheaper and having an epoxy coating.  It looks good to me.  The link you reference lists inductance as 7.39uH / turn^2, which is above Mads' recommended minimum of 5000nH (5uH).  For your 238kHz frequency, even a 2-turn GDT would avoid saturation.  (I'd recommend a few more turns to reduce magnetization current.)
David Knierim

Offline prabhatkumar

  • High Voltage Experimenter
  • **
  • Posts: 55
  • Karma: +0/-0
    • View Profile
Re: CORE FOR GDT AND CT
« Reply #5 on: April 14, 2020, 07:46:19 AM »
Thanks a lot klugesmith and davekni for your kind replies. Well I really appreciate how klugesmith taught how to calculate the inductance per turn just by formulas. And it's a shame for me as I still don't understand that level of details of electronics. And davekni also thanks for your advice on the core.
And something more bad also that I can't source anything from element 14 since they require a GST no so individuals and hobbyists like me can't buy straight from them . I will be updating this thread when I buy the cores from some other seller locally and trying it out ( the local vendors don't have the ferroxcube cores , they have only epcos cores like N-30 and T-38  and maybe few others ). Thanks everyone for now !

High Voltage Forum

Re: CORE FOR GDT AND CT
« Reply #5 on: April 14, 2020, 07:46:19 AM »

 


* Recent Topics and Posts

post Re: Isn't there a better way to make a custom toroid?
[General Chat]
johnf
Today at 01:33:47 AM
post MMC for a 32kvac load
[Capacitor Banks]
Rowdy
Today at 01:02:34 AM
post Re: Isn't there a better way to make a custom toroid?
[General Chat]
Rowdy
May 24, 2020, 11:47:26 PM
post Re: GDT cable specs
[Transformer (Ferrite Core)]
costas_p
May 24, 2020, 11:09:44 PM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
Rowdy
May 24, 2020, 10:39:45 PM
post Re: GDT cable specs
[Transformer (Ferrite Core)]
station240
May 24, 2020, 09:55:49 PM
post Re: Working Principle Of Neon Transformer Circuit
[Transformer (Ferrite Core)]
davekni
May 24, 2020, 09:55:48 PM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
Mads Barnkob
May 24, 2020, 08:16:40 PM
post Re: GDT cable specs
[Transformer (Ferrite Core)]
thecyberman
May 24, 2020, 05:38:27 PM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
Rowdy
May 24, 2020, 02:33:55 PM
post Re: Freewheeling diodes are burning (Now other problems)
[Solid State Tesla Coils (SSTC)]
hip424
May 24, 2020, 02:31:39 PM
post Re: Working Principle Of Neon Transformer Circuit
[Transformer (Ferrite Core)]
iraquois
May 24, 2020, 02:08:53 PM
post Re: Easy to build Polyphonic MIDI Interrupter
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
Max
May 24, 2020, 12:12:36 PM
post Re: Working Principle Of Neon Transformer Circuit
[Transformer (Ferrite Core)]
ritaismyconscience
May 24, 2020, 07:56:21 AM
post Re: Freewheeling diodes are burning (Now other problems)
[Solid State Tesla Coils (SSTC)]
ritaismyconscience
May 24, 2020, 03:09:57 AM
post Re: Working Principle Of Neon Transformer Circuit
[Transformer (Ferrite Core)]
davekni
May 23, 2020, 10:24:55 PM
post Re: GDT cable specs
[Transformer (Ferrite Core)]
johnf
May 23, 2020, 09:30:29 PM
post GDT cable specs
[Transformer (Ferrite Core)]
costas_p
May 23, 2020, 09:06:39 PM
post Re: Working Principle Of Neon Transformer Circuit
[Transformer (Ferrite Core)]
Mads Barnkob
May 23, 2020, 08:22:59 PM
post Re: Freewheeling diodes are burning (Now other problems)
[Solid State Tesla Coils (SSTC)]
davekni
May 23, 2020, 07:47:49 PM
post Re: Building a bigger DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
May 23, 2020, 07:41:41 PM
post Working Principle Of Neon Transformer Circuit
[Transformer (Ferrite Core)]
iraquois
May 23, 2020, 02:09:26 PM
post 600 Watt GEL Battery Charger Teardown - Signet Systems HB600-24B
[Electronic Circuits]
Mads Barnkob
May 23, 2020, 12:46:23 PM
post Re: Building a bigger DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ritaismyconscience
May 23, 2020, 04:14:52 AM
post Re: New projet OmegaDR
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ritaismyconscience
May 22, 2020, 01:15:36 AM
post Re: New projet OmegaDR
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mugi30
May 21, 2020, 11:55:37 PM
post Re: Easy to build Polyphonic MIDI Interrupter
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
Max
May 21, 2020, 07:46:28 PM
post Re: New projet OmegaDR
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mugi30
May 21, 2020, 09:15:57 AM
post Re: How to get rid of stuff?
[Sell / Buy / Trade]
johnf
May 21, 2020, 06:35:31 AM
post Re: How to get rid of stuff?
[Sell / Buy / Trade]
MRMILSTAR
May 21, 2020, 05:23:40 AM
post Re: Easy to build Polyphonic MIDI Interrupter
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
futurist
May 21, 2020, 12:16:04 AM
post Re: How to get rid of stuff?
[Sell / Buy / Trade]
klugesmith
May 20, 2020, 11:22:34 PM
post Re: Powerful easy to build MIDI Interrupter
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
Max
May 20, 2020, 12:15:43 PM
post Re: Portable Q(uarantine)CW Tesla Coil
[Dual Resonant Solid State Tesla coils (DRSSTC)]
SteveN87
May 19, 2020, 02:08:20 PM
post Re: New projet OmegaDR
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mugi30
May 19, 2020, 12:05:51 PM
post Re: Powerful easy to build MIDI Interrupter
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
Max
May 19, 2020, 11:49:02 AM
post Re: Powerful easy to build MIDI Interrupter
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
Mads Barnkob
May 19, 2020, 09:26:06 AM
post Re: Portable Q(uarantine)CW Tesla Coil
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Weston
May 19, 2020, 07:55:54 AM
post Re: What's the best way to trigger these things?
[Capacitor Banks]
klugesmith
May 19, 2020, 01:55:11 AM
post Re: New projet OmegaDR
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ritaismyconscience
May 18, 2020, 11:54:27 PM
post Re: New projet OmegaDR
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mugi30
May 18, 2020, 10:10:09 PM
post Re: New projet OmegaDR
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mugi30
May 18, 2020, 10:05:14 PM
post Re: What's the best way to trigger these things?
[Capacitor Banks]
johnf
May 18, 2020, 09:03:11 PM
post Re: What's the best way to trigger these things?
[Capacitor Banks]
John123
May 18, 2020, 07:50:08 PM
post Re: Powerful easy to build MIDI Interrupter
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
Max
May 18, 2020, 04:15:16 PM
post Re: Freewheeling diodes are burning (Now other problems)
[Solid State Tesla Coils (SSTC)]
hip424
May 18, 2020, 03:13:14 PM
post Re: How to get rid of stuff?
[Sell / Buy / Trade]
klugesmith
May 18, 2020, 06:31:25 AM
post Re: Building a bigger DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ritaismyconscience
May 18, 2020, 03:18:40 AM
post Re: What's the best way to trigger these things?
[Capacitor Banks]
davekni
May 18, 2020, 02:26:27 AM
post Re: What's the best way to trigger these things?
[Capacitor Banks]
rikkitikkitavi
May 17, 2020, 11:17:06 PM

Sitemap 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 
SimplePortal 2.3.6 © 2008-2014, SimplePortal