Author Topic: Gap distance between main bus bar  (Read 651 times)

Offline SAMGO

  • High Voltage Enthusiast
  • *
  • Posts: 19
  • Karma: +0/-0
    • View Profile
Gap distance between main bus bar
« on: October 26, 2021, 01:13:09 PM »
Hi to everyone, hope you are all doing well,

I'm now in the process of building a new DRSSTC and I have a question about my inverter design.
My inverter is based on two GD600HFY120C2S, see datasheet in attachement, running at around 560VDC from 3 phase supply. For the bus capacitance I'm using a 2s2p configuration of 4700uF 400VDC caps. The input of the 3 phase 80A rectifier is protected by 10A type C circuit breaker for added safety.

The gap between + and - it's now 2mm, this is okay for 560VDC but I was wondering if this could be a problem because of transients voltages.

If a transient comes it will be limited at the voltage necessary to fill the gap between + and - . In this way I can protect my IGBTs, maybe at the cost of loosing my 3 phase rectifier but it's cheaper and easy to change. The problem is that in this case the arc will also make the bus caps discharge and I have the feeling that is is not good and could kill the IGBTs in some strange way   :(

I'm now trying to decide between leaving it this way or putting a insulator layer / milling away some copper to enlarge the space between rails.

What do you think will be the better solution ?

Here is my Inverter so far, it's still missing the heatsink:




I also  made a small and simple circuit to safely discharge the main caps. The basic idea is to have an emergercy stop switch that will both open the 3 phase supply and put a power discharge resistor between + and - , this will also work if the 230V driver circuit it's un-plugged.

You can check it here:

Offline TMaxElectronics

  • High Voltage Engineer
  • ****
  • Posts: 229
  • Karma: +14/-0
    • View Profile
    • My random (and very empty) electronics blog
Re: Gap distance between main bus bar
« Reply #1 on: October 26, 2021, 06:38:24 PM »
With the width of your bus bars you could probably increase the spacing quite easily by drilling one of the mounting holes off-center. That would allow you to move the bus bar on the outer terminal further out, increasing the spacing considerably.

You will also need a pre-charge resistor for the dc bus. The inrush current of charging up such a large capacitance directly from the mains is massive, and will very likely cause problems.

I also think that a 10A breaker for such a high power coil is a little small. I managed to trip the breaker on my 3 phase 16A outlet in a matter of seconds with my skm400 coil and I suspect your inverter might do the same :)
And a type C breaker won't help do mucht to protect the semiconductors. if anything goes wrong the bus capacitance is likely enough to kill them by it self. I'd recommend just not installing a breaker on your coil directly, since all it would protect is the cabelling and that is already protected by the breaker in the distribution box.

Offline SAMGO

  • High Voltage Enthusiast
  • *
  • Posts: 19
  • Karma: +0/-0
    • View Profile
Re: Gap distance between main bus bar
« Reply #2 on: October 26, 2021, 08:29:08 PM »
With the width of your bus bars you could probably increase the spacing quite easily by drilling one of the mounting holes off-center. That would allow you to move the bus bar on the outer terminal further out, increasing the spacing considerably.

You will also need a pre-charge resistor for the dc bus. The inrush current of charging up such a large capacitance directly from the mains is massive, and will very likely cause problems.

I also think that a 10A breaker for such a high power coil is a little small. I managed to trip the breaker on my 3 phase 16A outlet in a matter of seconds with my skm400 coil and I suspect your inverter might do the same :)
And a type C breaker won't help do mucht to protect the semiconductors. if anything goes wrong the bus capacitance is likely enough to kill them by it self. I'd recommend just not installing a breaker on your coil directly, since all it would protect is the cabelling and that is already protected by the breaker in the distribution box.

Thanks TMax that's actually a good idea, I'll take note and see what to do when my fat heatsink arrives. Actually the holes are already off-center but I forgot that the widht of the busbars was changed last minute bruh :(

For the circuit breaker it's true that it doesn't add a lot of protection. I think I will go with the 10A one for the test phase and that evaluate to skip it when everything work as it should if necessary.
 
I agree with you about the pre-charge resistor, there is no way it will work if I attach it to 400VAC directly. For now I will be using a variac to be able to run it at a lower bus voltage. When everything works I will put 3 pre-charge resistors that get shorted after some seconds by a relais and regulate power via on-time.

Offline davekni

  • High Voltage Expert
  • ******
  • Posts: 1442
  • Karma: +70/-0
  • Physicist, engineer (electronic), and hobbiest
    • View Profile
Re: Gap distance between main bus bar
« Reply #3 on: October 26, 2021, 11:08:03 PM »
Quote
The gap between + and - it's now 2mm, this is okay for 560VDC but I was wondering if this could be a problem because of transients voltages.
If 2mm is air gap only, shouldn't be much risk.  A 2mm surface path (creepage distance) would be concerning.  Even for air, 3 or 4 or 5mm wouldn't hurt for comfort.  I'd think the risk is less from transients and more from any fine metal whiskers or other conductive debris falling or blowing across the gap and starting an arc.
David Knierim

Offline klugesmith

  • High Voltage Engineer
  • ****
  • Posts: 412
  • Karma: +13/-0
    • View Profile
Re: Gap distance between main bus bar
« Reply #4 on: October 27, 2021, 03:14:57 AM »
>> I'd think the risk is less from transients and more from any fine metal whiskers or other conductive debris falling or blowing across the gap and starting an arc.

At work we had a problem with low-voltage busbar parts made of copper and plated with pure tin.   Tin whisker growth is a real thing, even today.

Offline Duane B

  • High Voltage Enthusiast
  • *
  • Posts: 46
  • Karma: +2/-0
    • View Profile
    • Roaring 20s Superhets
Re: Gap distance between main bus bar
« Reply #5 on: October 27, 2021, 08:20:13 PM »
A 2mm gap might be troublesome with thermal expansion, dirt and debris over time. You might be better off increasing the distance of the gap and installing some type of MOV across the bus.
Duane Bylund

Offline klugesmith

  • High Voltage Engineer
  • ****
  • Posts: 412
  • Karma: +13/-0
    • View Profile
Re: Gap distance between main bus bar
« Reply #6 on: October 28, 2021, 07:59:25 PM »
You can look up clearance and creepage rules for your working voltage.
https://www.protoexpress.com/blog/importance-pcb-line-spacing-creepage-clearance/#Calculating_PCB_creepage_and_clearance

I would never depend on the 2 mm spacing as an intentional spark gap to protect components from an overvoltage transient.  So why not insert an insulating sheet to keep debris away from gap?

Offline SAMGO

  • High Voltage Enthusiast
  • *
  • Posts: 19
  • Karma: +0/-0
    • View Profile
Re: Gap distance between main bus bar
« Reply #7 on: November 06, 2021, 11:47:09 PM »
Quote
The gap between + and - it's now 2mm, this is okay for 560VDC but I was wondering if this could be a problem because of transients voltages.
If 2mm is air gap only, shouldn't be much risk.  A 2mm surface path (creepage distance) would be concerning.  Even for air, 3 or 4 or 5mm wouldn't hurt for comfort.  I'd think the risk is less from transients and more from any fine metal whiskers or other conductive debris falling or blowing across the gap and starting an arc.

A 2mm gap might be troublesome with thermal expansion, dirt and debris over time. You might be better off increasing the distance of the gap and installing some type of MOV across the bus.

You can look up clearance and creepage rules for your working voltage.
https://www.protoexpress.com/blog/importance-pcb-line-spacing-creepage-clearance/#Calculating_PCB_creepage_and_clearance

I would never depend on the 2 mm spacing as an intentional spark gap to protect components from an overvoltage transient.  So why not insert an insulating sheet to keep debris away from gap?

Thank to all of you for the suggestion! As a solution I will use a FR4 1.5mm spacer that is around 30kV of insulation so that I can first eliminate the debris problem (thanks I didn't thinked about that) and also augment the lenght of the creepage distance.


bdw Tin whisker growth it's very magical and spooky ahahhahahah those are the hard to find problems ....


Offline TMaxElectronics

  • High Voltage Engineer
  • ****
  • Posts: 229
  • Karma: +14/-0
    • View Profile
    • My random (and very empty) electronics blog
Re: Gap distance between main bus bar
« Reply #8 on: November 07, 2021, 01:44:42 AM »
Quote
bdw Tin whisker growth it's very magical and spooky ahahhahahah those are the hard to find problems ....
especially if they immediately get blown to pieces when they make contact and disappear ;)

Quote
I will use a FR4 1.5mm spacer that is around 30kV of insulation
Yeah that will probably improve the situation without too much effort. But I'm not so sure about the 30kV for 1.5mm FR4. I've seen normal mains (230V) cause tracking from one side of the board to the other before. But that might have been from heat/contamination with smoke machine fluid.

High Voltage Forum

Re: Gap distance between main bus bar
« Reply #8 on: November 07, 2021, 01:44:42 AM »

 


* Recent Topics and Posts

post Mixing PID loops
[General Chat]
Patrick
Today at 07:28:01 AM
post Re: Hi! 811 A tesa coil
[Vacuum Tube Tesla Coils (VTTC)]
jpvvv123
Today at 04:13:06 AM
post Re: Self Starting Coil (Not)
[Solid State Tesla Coils (SSTC)]
davekni
Today at 03:34:15 AM
post Self Starting Coil (Not)
[Solid State Tesla Coils (SSTC)]
alan sailer
January 23, 2022, 10:45:46 PM
post Re: GDT Slow Rise/Fall times even with resistor shorted
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
January 23, 2022, 09:06:49 PM
post GDT Slow Rise/Fall times even with resistor shorted
[Dual Resonant Solid State Tesla coils (DRSSTC)]
SalinsLV
January 23, 2022, 07:18:56 PM
post Re: Hi! 811 A tesa coil
[Vacuum Tube Tesla Coils (VTTC)]
304er
January 23, 2022, 06:18:13 PM
post Re: 120VAC Mains Ramped Builds
[Solid State Tesla Coils (SSTC)]
Magneticitist
January 22, 2022, 11:20:55 AM
post Re: 120VAC Mains Ramped Builds
[Solid State Tesla Coils (SSTC)]
ZakW
January 22, 2022, 07:07:09 AM
post Re: GDT Testing
[Solid State Tesla Coils (SSTC)]
johnf
January 22, 2022, 05:27:37 AM
post Re: Help on my "first" SSTC (LabCoatz SSTC 2.0)- Popping transistors
[Solid State Tesla Coils (SSTC)]
davekni
January 22, 2022, 04:27:38 AM
post Re: Hi! 811 A tesa coil
[Vacuum Tube Tesla Coils (VTTC)]
jpvvv123
January 22, 2022, 12:53:04 AM
post Re: 120VAC Mains Ramped Builds
[Solid State Tesla Coils (SSTC)]
Magneticitist
January 21, 2022, 07:36:07 PM
post Re: Muon Decay
[Detection, Counting and Measurements]
Uspring
January 21, 2022, 07:27:23 PM
post Re: Etching PCBs with a SLA 3d printer
[Printed Circuit Board]
TMaxElectronics
January 21, 2022, 02:05:52 PM
post Re: 120VAC Mains Ramped Builds
[Solid State Tesla Coils (SSTC)]
ZakW
January 21, 2022, 09:08:18 AM
post Re: Muon Decay
[Detection, Counting and Measurements]
Da_Stier
January 21, 2022, 08:42:54 AM
post 120VAC Mains Ramped Builds
[Solid State Tesla Coils (SSTC)]
Magneticitist
January 21, 2022, 03:00:04 AM
post Re: Muon Decay
[Detection, Counting and Measurements]
alan sailer
January 21, 2022, 02:16:57 AM
post Re: Help on my "first" SSTC (LabCoatz SSTC 2.0)- Popping transistors
[Solid State Tesla Coils (SSTC)]
TiagoBS
January 20, 2022, 06:56:35 PM
post Re: Muon Decay
[Detection, Counting and Measurements]
Da_Stier
January 20, 2022, 05:19:26 PM
post Re: Muon Decay
[Detection, Counting and Measurements]
alan sailer
January 20, 2022, 03:53:54 PM
post Re: Muon Decay
[Detection, Counting and Measurements]
Uspring
January 20, 2022, 01:20:19 PM
post Re: Muon Decay
[Detection, Counting and Measurements]
Da_Stier
January 20, 2022, 10:11:21 AM
post Re: Muon Decay
[Detection, Counting and Measurements]
alan sailer
January 19, 2022, 08:22:49 PM
post Re: Muon Decay
[Detection, Counting and Measurements]
Mads Barnkob
January 19, 2022, 06:49:36 PM
post Re: Etching PCBs with a SLA 3d printer
[Printed Circuit Board]
hardboiled99
January 19, 2022, 07:37:27 AM
post Primary Coil Winding Technique
[Solid State Tesla Coils (SSTC)]
alan sailer
January 18, 2022, 10:34:48 PM
post Re: Muon Decay
[Detection, Counting and Measurements]
alan sailer
January 18, 2022, 08:46:53 PM
post Re: Muon Decay
[Detection, Counting and Measurements]
Mads Barnkob
January 18, 2022, 08:08:53 PM
post Re: GDT Testing
[Solid State Tesla Coils (SSTC)]
ZakW
January 18, 2022, 07:15:22 PM
post Muon Decay
[Detection, Counting and Measurements]
alan sailer
January 18, 2022, 06:49:48 PM
post Re: Strange reading for grid feedback coil voltage
[Vacuum Tube Tesla Coils (VTTC)]
304er
January 18, 2022, 08:47:53 AM
post Re: QO-100 / EShail 2 Uplink amplifier development adventures
[Radio Frequency]
Da_Stier
January 17, 2022, 09:13:32 PM
post Re: QO-100 / EShail 2 Uplink amplifier development adventures
[Radio Frequency]
Da_Stier
January 17, 2022, 09:05:56 PM
post Re: Help on my "first" SSTC (LabCoatz SSTC 2.0)- Popping transistors
[Solid State Tesla Coils (SSTC)]
Mads Barnkob
January 17, 2022, 07:45:48 PM
post Re: General Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
January 17, 2022, 07:41:34 PM
post Re: Strange reading for grid feedback coil voltage
[Vacuum Tube Tesla Coils (VTTC)]
Mads Barnkob
January 17, 2022, 07:38:25 PM
post Re: SSTC with push-pull configuration
[Solid State Tesla Coils (SSTC)]
Mads Barnkob
January 17, 2022, 07:31:03 PM
post Re: GDT Testing
[Solid State Tesla Coils (SSTC)]
Mads Barnkob
January 17, 2022, 07:28:02 PM
post Re: Induction heater Driver for Flyback?
[Voltage Multipliers]
MRMILSTAR
January 16, 2022, 09:00:02 PM
post Induction heater Driver for Flyback?
[Voltage Multipliers]
abstruse1
January 16, 2022, 07:35:26 PM
post Re: SSTC with push-pull configuration
[Solid State Tesla Coils (SSTC)]
Bambinz
January 16, 2022, 12:21:40 PM
post Re: SSTC with push-pull configuration
[Solid State Tesla Coils (SSTC)]
davekni
January 15, 2022, 07:10:03 PM
post Re: SSTC with push-pull configuration
[Solid State Tesla Coils (SSTC)]
Bambinz
January 15, 2022, 06:31:33 PM
post Re: SSTC with push-pull configuration
[Solid State Tesla Coils (SSTC)]
Magneticitist
January 14, 2022, 08:47:43 PM
post Re: SSTC with push-pull configuration
[Solid State Tesla Coils (SSTC)]
davekni
January 14, 2022, 08:39:07 PM
post Re: Unusual Youtube channel activity
[General Chat]
davekni
January 14, 2022, 08:14:17 PM
post Re: Unusual Youtube channel activity
[General Chat]
Mads Barnkob
January 14, 2022, 08:12:13 PM
post Unusual Youtube channel activity
[General Chat]
MRMILSTAR
January 14, 2022, 05:51:52 PM
post Re: Strange reading for grid feedback coil voltage
[Vacuum Tube Tesla Coils (VTTC)]
304er
January 14, 2022, 08:51:57 AM
post Re: SSTC with push-pull configuration
[Solid State Tesla Coils (SSTC)]
Bambinz
January 13, 2022, 08:20:02 PM
post Re: Help with SSTC feedback circuits with 4046 IC and Schmitt Triggers
[Solid State Tesla Coils (SSTC)]
davekni
January 13, 2022, 05:27:40 AM
post Re: General Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
thedoc298
January 13, 2022, 03:10:32 AM
post Re: Strange reading for grid feedback coil voltage
[Vacuum Tube Tesla Coils (VTTC)]
304er
January 12, 2022, 06:18:15 PM
post Re: Single mosfet bifiliar gdt
[Solid State Tesla Coils (SSTC)]
alan sailer
January 12, 2022, 05:45:26 PM
post Re: Strange reading for grid feedback coil voltage
[Vacuum Tube Tesla Coils (VTTC)]
MRMILSTAR
January 12, 2022, 03:29:04 PM
post Re: Help with SSTC feedback circuits with 4046 IC and Schmitt Triggers
[Solid State Tesla Coils (SSTC)]
AFreshLad
January 12, 2022, 01:30:38 PM
post Re: Strange reading for grid feedback coil voltage
[Vacuum Tube Tesla Coils (VTTC)]
304er
January 12, 2022, 09:09:13 AM
post Re: Strange reading for grid feedback coil voltage
[Vacuum Tube Tesla Coils (VTTC)]
MRMILSTAR
January 11, 2022, 08:05:27 PM
post Re: Nokia Siemens 3G Flexi 2100MHz 50W Amplifier Teardown
[Radio Frequency]
Mads Barnkob
January 11, 2022, 07:42:12 PM
post Re: Strange reading for grid feedback coil voltage
[Vacuum Tube Tesla Coils (VTTC)]
Duane B
January 11, 2022, 07:33:15 PM
post Re: 8x MOT transformer, weird power draw
[Transformer (Iron Core)]
AstRii
January 11, 2022, 06:19:49 PM
post Re: Strange reading for grid feedback coil voltage
[Vacuum Tube Tesla Coils (VTTC)]
304er
January 11, 2022, 05:19:46 PM
post Re: Strange reading for grid feedback coil voltage
[Vacuum Tube Tesla Coils (VTTC)]
MRMILSTAR
January 11, 2022, 04:31:28 PM
post Re: 8x MOT transformer, weird power draw
[Transformer (Iron Core)]
AstRii
January 11, 2022, 03:21:37 PM
post Re: GDT Testing
[Solid State Tesla Coils (SSTC)]
davekni
January 11, 2022, 06:50:49 AM
post Re: Strange reading for grid feedback coil voltage
[Vacuum Tube Tesla Coils (VTTC)]
Duane B
January 11, 2022, 06:34:20 AM
post Re: Help on my "first" SSTC (LabCoatz SSTC 2.0)- Popping transistors
[Solid State Tesla Coils (SSTC)]
davekni
January 11, 2022, 06:24:13 AM
post Re: Strange reading for grid feedback coil voltage
[Vacuum Tube Tesla Coils (VTTC)]
davekni
January 11, 2022, 06:15:08 AM
post Re: Strange reading for grid feedback coil voltage
[Vacuum Tube Tesla Coils (VTTC)]
MRMILSTAR
January 11, 2022, 05:25:31 AM
post Re: Strange reading for grid feedback coil voltage
[Vacuum Tube Tesla Coils (VTTC)]
Duane B
January 11, 2022, 12:07:22 AM
post Strange reading for grid feedback coil voltage
[Vacuum Tube Tesla Coils (VTTC)]
MRMILSTAR
January 10, 2022, 10:56:48 PM
post Re: Hi! 811 A tesa coil
[Vacuum Tube Tesla Coils (VTTC)]
Duane B
January 10, 2022, 09:38:53 PM
post Re: Help on my "first" SSTC (LabCoatz SSTC 2.0)- Popping transistors
[Solid State Tesla Coils (SSTC)]
ZakW
January 10, 2022, 07:50:13 PM
post Re: GDT Testing
[Solid State Tesla Coils (SSTC)]
ZakW
January 10, 2022, 07:19:17 PM
post Re: Help on my "first" SSTC (LabCoatz SSTC 2.0)- Popping transistors
[Solid State Tesla Coils (SSTC)]
TiagoBS
January 10, 2022, 03:13:08 PM
post Re: GDT Testing
[Solid State Tesla Coils (SSTC)]
davekni
January 10, 2022, 04:21:46 AM
post Re: Hi! 811 A tesa coil
[Vacuum Tube Tesla Coils (VTTC)]
304er
January 10, 2022, 03:59:09 AM
post Re: 8x MOT transformer, weird power draw
[Transformer (Iron Core)]
davekni
January 10, 2022, 03:54:59 AM
post Re: GDT Testing
[Solid State Tesla Coils (SSTC)]
ZakW
January 09, 2022, 11:45:09 PM
post Re: Hi! 811 A tesa coil
[Vacuum Tube Tesla Coils (VTTC)]
jpvvv123
January 09, 2022, 11:04:25 PM
post 8x MOT transformer, weird power draw
[Transformer (Iron Core)]
AstRii
January 09, 2022, 04:22:11 PM
post Re: Hi! 811 A tesa coil
[Vacuum Tube Tesla Coils (VTTC)]
Duane B
January 09, 2022, 05:52:11 AM
post Re: GDT Testing
[Solid State Tesla Coils (SSTC)]
davekni
January 09, 2022, 05:10:50 AM
post Re: Performance issues regarding phase angle in SSTCs
[Solid State Tesla Coils (SSTC)]
davekni
January 09, 2022, 01:20:40 AM
post GDT Testing
[Solid State Tesla Coils (SSTC)]
ZakW
January 09, 2022, 12:38:28 AM
post Re: General Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
January 08, 2022, 06:36:28 PM
post Performance issues regarding phase angle in SSTCs
[Solid State Tesla Coils (SSTC)]
Max Seiringer
January 08, 2022, 03:21:31 PM
post Re: Hi! 811 A tesa coil
[Vacuum Tube Tesla Coils (VTTC)]
304er
January 08, 2022, 09:05:41 AM
post Re: Hi! 811 A tesa coil
[Vacuum Tube Tesla Coils (VTTC)]
jpvvv123
January 07, 2022, 10:20:10 PM
post Re: Hi! 811 A tesa coil
[Vacuum Tube Tesla Coils (VTTC)]
304er
January 07, 2022, 05:56:28 PM
post Re: First SSTC based on profdc9 PCB Pack
[Solid State Tesla Coils (SSTC)]
davekni
January 07, 2022, 05:15:38 AM
post Re: DRSSTC tuning
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
January 07, 2022, 05:01:21 AM
post Re: How to prevent secondary to secondary to primary arcs?
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
January 07, 2022, 04:59:59 AM
post Tophat QCW 1
[Dual Resonant Solid State Tesla coils (DRSSTC)]
dbach
January 07, 2022, 02:27:35 AM
post How to prevent secondary to secondary to primary arcs?
[Dual Resonant Solid State Tesla coils (DRSSTC)]
dbach
January 07, 2022, 02:19:40 AM
post Re: General Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
January 06, 2022, 09:33:06 PM
post Re: First SSTC based on profdc9 PCB Pack
[Solid State Tesla Coils (SSTC)]
alan sailer
January 06, 2022, 06:09:39 PM
post Re: DRSSTC tuning
[Dual Resonant Solid State Tesla coils (DRSSTC)]
kubajed
January 06, 2022, 04:48:22 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