Author Topic: Primary-Strike Protection Grounding Scheme - Insanity?  (Read 341 times)

Offline nabzim

  • High Voltage Enthusiast
  • *
  • Posts: 24
  • 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: 226
  • Karma: +6/-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 Experimenter
  • **
  • Posts: 93
  • Karma: +1/-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: 24
  • 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: 24
  • 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: New DRSSTC broken - Help
[Dual Resonant Solid State Tesla coils]
Laci
Today at 09:41:43 AM
post Let's study DRSSTC, how does it work by running ORCAD simulation
[Dual Resonant Solid State Tesla coils]
VNTC
Today at 06:09:00 AM
post Re: Strange GDT signals (need to help)
[Dual Resonant Solid State Tesla coils]
VNTC
Today at 03:39:48 AM
post Re: New DRSSTC broken - Help
[Dual Resonant Solid State Tesla coils]
MEROVINGO85
Today at 01:19:22 AM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
hightemp1
May 23, 2019, 11:20:08 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
badpeter
May 23, 2019, 09:54:18 PM
post Re: New DRSSTC broken - Help
[Dual Resonant Solid State Tesla coils]
Teravolt
May 23, 2019, 09:19:34 PM
post Re: Next Gen DRSSTC
[Dual Resonant Solid State Tesla coils]
Netzpfuscher
May 23, 2019, 09:01:24 PM
post New DRSSTC broken - Help
[Dual Resonant Solid State Tesla coils]
MEROVINGO85
May 23, 2019, 08:18:56 PM
post Re: (DR)SSTC music MIDI files
[Dual Resonant Solid State Tesla coils]
profdc9
May 23, 2019, 05:36:38 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
hightemp1
May 23, 2019, 04:56:10 PM
post Re: Strange GDT signals (need to help)
[Dual Resonant Solid State Tesla coils]
Phoenix
May 23, 2019, 11:55:27 AM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
hightemp1
May 23, 2019, 05:51:09 AM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
May 23, 2019, 04:07:17 AM
post Strange GDT signals (need to help)
[Dual Resonant Solid State Tesla coils]
VNTC
May 23, 2019, 02:19:24 AM
post Re: Easy access to optimal resonance frequency but the benefit is quite small
[Dual Resonant Solid State Tesla coils]
VNTC
May 23, 2019, 02:00:48 AM
post Re: Strange gdt waveforms
[Dual Resonant Solid State Tesla coils]
VNTC
May 23, 2019, 01:33:56 AM
post Re: DRSSTC design questions + project progress
[Dual Resonant Solid State Tesla coils]
Mads Barnkob
May 22, 2019, 08:31:55 PM
post Re: Easy access to optimal resonance frequency but the benefit is quite small
[Dual Resonant Solid State Tesla coils]
dexter
May 22, 2019, 08:31:51 PM
post Easy access to optimal resonance frequency but the benefit is quite small
[Dual Resonant Solid State Tesla coils]
VNTC
May 21, 2019, 11:35:57 PM
post Re: Offgrid 48V solar to 24V battery setup
[Electronic circuits]
Mads Barnkob
May 21, 2019, 09:59:54 PM
post Re: General Oscilloscope Probing Techniques for (DR)SSTC h-bridge
[Beginners]
Mads Barnkob
May 21, 2019, 09:51:27 PM
post Re: ZVS Mazzilli circ with active gate driver - what causes ringing?
[Electronic circuits]
T3sl4co1l
May 21, 2019, 09:49:03 PM
post Re: ZVS Mazzilli circ with active gate driver - what causes ringing?
[Electronic circuits]
82026
May 21, 2019, 09:02:10 PM
post Re: DRSSTC design questions + project progress
[Dual Resonant Solid State Tesla coils]
Vaclav
May 21, 2019, 08:59:57 PM
post Re: DRSSTC design questions + project progress
[Dual Resonant Solid State Tesla coils]
Mads Barnkob
May 21, 2019, 08:28:43 PM
post Re: Identification of unknown embedded computer, help needed.
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
Mads Barnkob
May 21, 2019, 08:22:28 PM
post Re: DRSSTC design questions + project progress
[Dual Resonant Solid State Tesla coils]
Vaclav
May 21, 2019, 06:21:37 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
May 21, 2019, 06:12:55 PM
post Re: DRSSTC design questions + project progress
[Dual Resonant Solid State Tesla coils]
profdc9
May 21, 2019, 04:06:38 PM
post Re: DRSSTC design questions + project progress
[Dual Resonant Solid State Tesla coils]
Vaclav
May 21, 2019, 03:56:56 PM
post Re: DRSSTC design questions + project progress
[Dual Resonant Solid State Tesla coils]
Vaclav
May 21, 2019, 03:46:56 PM
post Re: DRSSTC design questions + project progress
[Dual Resonant Solid State Tesla coils]
profdc9
May 21, 2019, 02:32:59 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
May 21, 2019, 06:12:18 AM
post Re: Offgrid 48V solar to 24V battery setup
[Electronic circuits]
profdc9
May 20, 2019, 11:30:34 PM
post DRSSTC design questions + project progress
[Dual Resonant Solid State Tesla coils]
Vaclav
May 20, 2019, 06:38:54 PM
post Re: General Oscilloscope Probing Techniques for (DR)SSTC h-bridge
[Beginners]
Teravolt
May 20, 2019, 06:33:49 PM
post Re: ZVS Mazzilli circ with active gate driver - what causes ringing?
[Electronic circuits]
82026
May 20, 2019, 02:27:59 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
hightemp1
May 20, 2019, 02:57:46 AM
post Re: ZVS Mazzilli circ with active gate driver - what causes ringing?
[Electronic circuits]
T3sl4co1l
May 20, 2019, 01:06:27 AM
post Re: ZVS Mazzilli circ with active gate driver - what causes ringing?
[Electronic circuits]
82026
May 19, 2019, 09:14:59 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
May 19, 2019, 06:40:41 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
flyrod
May 19, 2019, 04:04:12 PM
post Re: Offgrid 48V solar to 24V battery setup
[Electronic circuits]
Mads Barnkob
May 19, 2019, 11:24:46 AM
post Re: ZVS Mazzilli circ with active gate driver - what causes ringing?
[Electronic circuits]
flyrod
May 19, 2019, 03:22:54 AM
post Re: Are bleeder resistors necessary if I can easily discharge my capacitor?
[Spark gap Tesla coils]
profdc9
May 19, 2019, 03:18:52 AM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
May 18, 2019, 10:48:59 PM
post Re: Is one of these good?
[Dual Resonant Solid State Tesla coils]
Golddustpeak
May 18, 2019, 04:19:11 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
May 17, 2019, 10:57:17 PM
post Are bleeder resistors necessary if I can easily discharge my capacitor?
[Spark gap Tesla coils]
jpb133
May 17, 2019, 09:41:56 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