Author Topic: Primary-Strike Protection Grounding Scheme - Insanity?  (Read 889 times)

Offline nabzim

  • High Voltage Enthusiast
  • *
  • Posts: 25
  • Karma: +0/-0
  • My full name is Adam Baltazar Mizban. Hello there!
    • View Profile
    • My YouTube Channel
Primary-Strike Protection Grounding Scheme - Insanity?
« on: February 18, 2019, 05:06:18 AM »
OK. So we are all familiar with the standard method of primary-strike protection, that is, connecting the RF-ground to the negative DC Bus via capacitive-coupling...
I have come to the realization, that this does NOT make sense.

If a streamer strikes your primary coil, the streamer-current must travel through one/both of your low-side IGBT's (full bridge), or through your low-side IGBT and/or Bus Capacitor (half bridge) to get from the Primary coil to the -Vbus rail.

Why is it not instead the standard to capacitively-couple the RF-ground directly to the Primary Coil? (a.k.a. the center-point, between high-side and low-side IGBT's)
This would keep the high-energy current from traveling through the semiconductor.

Are my assumptions here correct? If there is any logical reasoning behind the standard grounding-scheme (other than copying Steve Ward), then can someone please educate me? ???

Offline Hydron

  • Administrator
  • High Voltage Engineer
  • *****
  • Posts: 302
  • Karma: +9/-0
    • View Profile
Re: Primary-Strike Protection Grounding Scheme - Insanity?
« Reply #1 on: February 18, 2019, 08:44:19 AM »
Coupling the non-MMC end of the primary would put a significant load on the bridge - take a look at the impedance of the typical coupling caps (e.g. 0.1uF) at the switching frequency. I suspect it would also cause EMI and safety issues, as any current through this capacitor would have to flow via the mains wiring to wherever the earth-neutral bond point is.

Given that the issue doesn't seem to be the strike current (on the order of a few amps only) flowing through the igbts (which have anti parallel diodes included to provide a path when off) but was more about voltage stress between the bridge and heatsink (ground) when hit, the standard method seems to do the trick.

Offline Teravolt

  • High Voltage Technician
  • ***
  • Posts: 104
  • Karma: +2/-0
    • View Profile
Re: Primary-Strike Protection Grounding Scheme - Insanity?
« Reply #2 on: February 18, 2019, 09:25:24 PM »
adding beafy varistors from the primary to ground should increase robustness and a decent strike rail to ground is common practice hear

Offline nabzim

  • High Voltage Enthusiast
  • *
  • Posts: 25
  • Karma: +0/-0
  • My full name is Adam Baltazar Mizban. Hello there!
    • View Profile
    • My YouTube Channel
Re: Primary-Strike Protection Grounding Scheme - Insanity?
« Reply #3 on: March 06, 2019, 08:33:48 AM »
Coupling the non-MMC end of the primary would put a significant load on the bridge - take a look at the impedance of the typical coupling caps (e.g. 0.1uF) at the switching frequency. I suspect it would also cause EMI and safety issues, as any current through this capacitor would have to flow via the mains wiring to wherever the earth-neutral bond point is.

Given that the issue doesn't seem to be the strike current (on the order of a few amps only) flowing through the igbts (which have anti parallel diodes included to provide a path when off) but was more about voltage stress between the bridge and heatsink (ground) when hit, the standard method seems to do the trick.
Thank you. I'm most likely going with the negative rail.

Offline nabzim

  • High Voltage Enthusiast
  • *
  • Posts: 25
  • Karma: +0/-0
  • My full name is Adam Baltazar Mizban. Hello there!
    • View Profile
    • My YouTube Channel
Re: Primary-Strike Protection Grounding Scheme - Insanity?
« Reply #4 on: March 06, 2019, 08:47:41 AM »
adding beafy varistors from the primary to ground should increase robustness and a decent strike rail to ground is common practice hear

MOV's in addition to the capacitor? and in parallel, I'm assuming?

Grounded strike rail is a certainty! It sure comes in handy on my spark-gap coil: youtu.be/3d4ZDvA5Kcc   

High Voltage Forum

Re: Primary-Strike Protection Grounding Scheme - Insanity?
« Reply #4 on: March 06, 2019, 08:47:41 AM »

 


* Recent Topics and Posts

post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
Today at 04:15:12 AM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ritaismyconscience
Today at 01:05:28 AM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
SteveN87
Today at 12:53:15 AM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
April 07, 2020, 10:54:57 PM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ritaismyconscience
April 07, 2020, 10:24:16 PM
post Re: Class E SSTC Topology
[Solid State Tesla Coils (SSTC)]
ZakW
April 07, 2020, 09:22:16 PM
post Re: Class E SSTC Topology
[Solid State Tesla Coils (SSTC)]
johnf
April 07, 2020, 09:04:34 PM
post Re: Class E SSTC Topology
[Solid State Tesla Coils (SSTC)]
ZakW
April 07, 2020, 08:48:01 PM
post Re: Class E SSTC Topology
[Solid State Tesla Coils (SSTC)]
Weston
April 07, 2020, 08:15:43 PM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
John123
April 07, 2020, 06:23:47 PM
post Re: Where is plasma globe arc arcing to?
[Beginners]
John123
April 07, 2020, 05:59:09 PM
post Re: Where is plasma globe arc arcing to?
[Beginners]
alan sailer
April 07, 2020, 04:30:26 PM
post Re: Powerful easy to build MIDI Interrupter
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
Max
April 07, 2020, 01:10:30 PM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
SteveN87
April 07, 2020, 12:44:56 PM
post Re: Where is plasma globe arc arcing to?
[Beginners]
John123
April 07, 2020, 07:05:30 AM
post Re: Where is plasma globe arc arcing to?
[Beginners]
Jun
April 07, 2020, 06:40:02 AM
post Re: Class E SSTC Topology
[Solid State Tesla Coils (SSTC)]
ZakW
April 07, 2020, 05:07:31 AM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
John123
April 07, 2020, 03:38:12 AM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
SteveN87
April 07, 2020, 03:21:55 AM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
John123
April 07, 2020, 02:59:28 AM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
davekni
April 07, 2020, 02:52:19 AM
post Re: Small DIY plasma globe using ZVS oscillator
[Transformer (Ferrite Core)]
John123
April 07, 2020, 02:29:21 AM
post Re: Where is plasma globe arc arcing to?
[Beginners]
John123
April 07, 2020, 02:21:55 AM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
John123
April 07, 2020, 02:00:26 AM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
SteveN87
April 07, 2020, 01:25:47 AM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
John123
April 07, 2020, 12:38:59 AM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
petespaco
April 07, 2020, 12:13:11 AM
post Re: Corona lockdown thread, tell about your situation
[General Chat]
John123
April 06, 2020, 10:07:59 PM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
davekni
April 06, 2020, 10:07:11 PM
post Re: Corona lockdown thread, tell about your situation
[General Chat]
Mads Barnkob
April 06, 2020, 09:57:29 PM
post Re: TVS diode selection for 400v transistor
[Electronic Circuits]
John123
April 06, 2020, 08:04:52 PM
post Re: Power MOSFETs with fast recovery body diodes
[Electronic Circuits]
John123
April 06, 2020, 07:49:30 PM
post Re: Where is plasma globe arc arcing to?
[Beginners]
davekni
April 06, 2020, 06:30:24 PM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
April 06, 2020, 06:23:27 PM
post Where is plasma globe arc arcing to?
[Beginners]
Jun
April 06, 2020, 02:10:18 PM
post Re: Interuppter code help for sstc (LONEOCEANS SSTC2 )
[Solid State Tesla Coils (SSTC)]
Max
April 06, 2020, 10:21:47 AM
post Journey to a small stand alone CW signal synthesizer
[Radio Frequency]
Da_Stier
April 06, 2020, 09:56:07 AM
post Re: GDT keeps on killing IGBTs
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ritaismyconscience
April 06, 2020, 05:09:29 AM
post Re: Class E SSTC Topology
[Solid State Tesla Coils (SSTC)]
ZakW
April 06, 2020, 02:26:28 AM
post Re: Skm100 coil
[Dual Resonant Solid State Tesla coils (DRSSTC)]
oneKone
April 06, 2020, 02:16:56 AM
post Re: Portable Q(uarantine)CW Tesla Coil
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
April 06, 2020, 12:43:50 AM
post Portable Q(uarantine)CW Tesla Coil
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Weston
April 05, 2020, 10:47:07 PM
post Re: Unconventional 3kW SSTC
[Solid State Tesla Coils (SSTC)]
davekni
April 05, 2020, 10:46:48 PM
post Re: Interuppter code help for sstc (LONEOCEANS SSTC2 )
[Solid State Tesla Coils (SSTC)]
Max
April 05, 2020, 10:09:40 PM
post Re: Interuppter code help for sstc (LONEOCEANS SSTC2 )
[Solid State Tesla Coils (SSTC)]
ritaismyconscience
April 05, 2020, 09:55:33 PM
post Re: Royer oscillator (ZVS) driven Jacob's ladder, E80 core transformer
[Transformer (Ferrite Core)]
davekni
April 05, 2020, 06:53:57 PM
post Re: Corona lockdown thread, tell about your situation
[General Chat]
Uspring
April 05, 2020, 06:18:50 PM
post Interuppter code help for sstc (LONEOCEANS SSTC2 )
[Solid State Tesla Coils (SSTC)]
prabhatkumar
April 05, 2020, 05:20:57 PM
post Optical flatness inspection
[Light, Lasers and Optics]
klugesmith
April 05, 2020, 08:20:08 AM
post Re: Corona lockdown thread, tell about your situation
[General Chat]
klugesmith
April 05, 2020, 07:49:27 AM

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