Author Topic: Using metallized film caps instead of foil caps in MMC  (Read 1012 times)

Offline NickyLee

  • High Voltage Enthusiast
  • *
  • Posts: 3
  • Karma: +0/-0
    • View Profile
Using metallized film caps instead of foil caps in MMC
« on: May 28, 2023, 06:55:34 PM »
Hello everyone, this is my first time visiting this forum so please excuse and correct any etiquette oversights on my part.

I would like to collect some opinions on using metalized film capacitors in MMCs.

I have heard using them is a no-no for reliability reasons, but I have also seen builds that use them. I would love to be able to use them for my build for budget reasons, but I know that choice will probably come back and bite my a** later. The bank would be about .02uf and around 25-30kv rated. JavaTC says the coil will resonate at about 115kHz if that's important. I can share other coil info if needed.

If people have experience or stories of using metalized film caps instead of foil caps please share them. Any input is appreciated

Offline Twospoons

  • High Voltage Engineer
  • ****
  • Posts: 239
  • Karma: +6/-0
    • View Profile
Re: Using metallized film caps instead of foil caps in MMC
« Reply #1 on: May 28, 2023, 11:37:12 PM »
The problem with met-film is that high peak currents can burn away the metalization from the end connection. If you have an I2t rating for your caps, and you know the voltage and frequency of operation, you can check your peak current will be within limits.  Be aware that supplied I2t generally assumes a half-sine pulse at 50 or 60 Hz, which may not be valid for high frequencies.  I would recommend derating.

Some years back I was working designing electric fence energisers, using 1200V met-film caps. Based off the I2t from the manufacturer, everything should have been within spec, but after a week of running my prototypes died - because the end termination had burnt away inside the caps. After talking to the manufacturer, describing the issue and our application, they revised the I2t down by almost 50%.   The difference was our circuit was draining the caps in a 100us pulse, not the 10ms half sine assumed by the original rating.

Offline NickyLee

  • High Voltage Enthusiast
  • *
  • Posts: 3
  • Karma: +0/-0
    • View Profile
Re: Using metallized film caps instead of foil caps in MMC
« Reply #2 on: May 30, 2023, 04:05:35 AM »
Thank you for your input.

The caps I'm looking at (R76TN31505050J) have no mention of an I2t rating but they do have a non-repeated max pulse current of 450A. I'm planning on running 3 strings in parallel in my MMC for a combined max pulse rating of 1350A. JavaTC estimated the peak pulse current to be around 230A, so hopefully that is enough margin for some amount of fun before failure.

Offline davekni

  • Executive Board Member
  • *******
  • Posts: 2820
  • Karma: +134/-1
  • Physicist, engineer (electronic), and hobbiest
    • View Profile
Re: Using metallized film caps instead of foil caps in MMC
« Reply #3 on: May 30, 2023, 04:06:53 AM »
Quote
I would like to collect some opinions on using metalized film capacitors in MMCs.
Depends greatly on the particular capacitor.  As Twospoons recommends, check capacitor specifications.  RMS current capability is key, and peak current (peak CdV/dt).  Some capacitors are combinations of foil and film.  And, of course, polypropylene dielectric.
If you have the luxury of access to a thermal imager, test a capacitor with high frequency AC current.  Good ones will be relatively cool overall, with warmest part in the middle, since leads provide some heat sinking.  Bad film parts (with poor connections to end of foil roll) will be hot at ends by leads.

Quote
The caps I'm looking at (R76TN31505050J) have no mention of an I2t rating
Instead they have a V^2/t rating, of 9.6E12 V^2/second for that part.  Multiply by C^2 (by 0.15E-6 ^ 2) to get I2t.
RMS current is listed as 16A, down to 6.3A at 85C.  That may be most limiting specification.  Depends on your planned duty cycle and cooling.  And on desired life time.  Specifications are generally for commercial use where caps are expected to have good reliability for long term product use.  TCs are often used for only a few hours during their entire existence.
« Last Edit: May 30, 2023, 04:21:30 AM by davekni »
David Knierim

Offline NickyLee

  • High Voltage Enthusiast
  • *
  • Posts: 3
  • Karma: +0/-0
    • View Profile
Re: Using metallized film caps instead of foil caps in MMC
« Reply #4 on: June 03, 2023, 09:57:35 PM »
I plugged everything as best I could into the Kaizer Power MMC calculator and everything looks good. All the power parameters have a SF of 2.1 or (much) greater, and the single cap temperature rise is 4.4 C.

High Voltage Forum

Re: Using metallized film caps instead of foil caps in MMC
« Reply #4 on: June 03, 2023, 09:57:35 PM »

 


* Recent Topics and Posts

post Re: Steve Ward's DRSSTC Interrupter stops working when adjusting pulse width
[Electronic Circuits]
petespaco
Today at 04:52:08 PM
post Re: Turning SSTC into DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Simranjit
Today at 02:14:17 AM
post Re: Turning SSTC into DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
June 12, 2024, 11:04:57 PM
post Turning SSTC into DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Simranjit
June 12, 2024, 10:23:08 PM
post Re: UD2.7C constantly in OCP despite having signal
[Dual Resonant Solid State Tesla coils (DRSSTC)]
verliebt_in_neukölln17
June 12, 2024, 08:41:06 PM
post Re: UD2.7C constantly in OCP despite having signal
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
June 12, 2024, 07:53:31 PM
post Re: Van de Graaf Voltage measurement with voltage sensor and voltage divider
[Static Electricity]
haversin
June 12, 2024, 06:57:13 PM
post UD2.7C constantly in OCP despite having signal
[Dual Resonant Solid State Tesla coils (DRSSTC)]
verliebt_in_neukölln17
June 12, 2024, 06:54:49 PM
post Re: Van de Graaf Voltage measurement with voltage sensor and voltage divider
[Static Electricity]
Mads Barnkob
June 12, 2024, 03:47:28 PM
post Van de Graaf Voltage measurement with voltage sensor and voltage divider
[Static Electricity]
vK
June 12, 2024, 03:42:18 AM
post Re: Bigger sparks?...
[Vacuum Tube Tesla Coils (VTTC)]
davekni
June 12, 2024, 03:32:22 AM
post Re: Bigger sparks?...
[Vacuum Tube Tesla Coils (VTTC)]
Teslaventje
June 11, 2024, 11:05:49 PM
post Re: Bigger sparks?...
[Vacuum Tube Tesla Coils (VTTC)]
MRMILSTAR
June 11, 2024, 05:36:46 AM
post Re: Sling Psychrometer
[Laboratories, Equipment and Tools]
Twospoons
June 11, 2024, 12:29:31 AM
post Bigger sparks?...
[Vacuum Tube Tesla Coils (VTTC)]
Teslaventje
June 10, 2024, 11:05:55 PM
post Re: Syntherrupter - A Feature-rich, Polyphonic Interrupter
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
Max
June 10, 2024, 10:57:51 PM
post Re: Benjamin's DRSSTC3
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
June 10, 2024, 08:08:04 PM
post Re: Plasma Torid - Class E Self Resonant Dual/Stereo - Plasma Torid Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Hi-Deff
June 10, 2024, 06:04:09 PM
post Sling Psychrometer
[Laboratories, Equipment and Tools]
klugesmith
June 10, 2024, 04:43:59 PM
post Re: Benjamin's DRSSTC3
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
June 10, 2024, 03:35:28 PM
post Re: Benjamin's DRSSTC3
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Jj
June 10, 2024, 01:36:41 PM
post Re: Is a 60UF 800VDC Dawncap good for an induction heater?
[General Chat]
Anders Mikkelsen
June 09, 2024, 05:44:29 PM
post Is a 60UF 800VDC Dawncap good for an induction heater?
[General Chat]
yourboi
June 09, 2024, 03:31:30 PM
post Re: Steve Ward's DRSSTC Interrupter stops working when adjusting pulse width
[Electronic Circuits]
NyaaX_X
June 09, 2024, 01:34:49 PM
post Steve Ward's DRSSTC Interrupter stops working when adjusting pulse width
[Electronic Circuits]
verliebt_in_neukölln17
June 09, 2024, 01:56:51 AM
post Re: Return of Electronics Flea Market in "Silicon Valley"
[Sell / Buy / Trade]
klugesmith
June 08, 2024, 06:06:25 AM
post Re: Coulometric hourmeters
[Laboratories, Equipment and Tools]
klugesmith
June 08, 2024, 05:38:14 AM
post Interrupter for SSTC
[Beginners]
Simranjit
June 08, 2024, 12:47:47 AM
post Re: Adding capacitor to primary in SSTC
[Solid State Tesla Coils (SSTC)]
Michelle_
June 07, 2024, 03:59:57 PM
post Re: Adding capacitor to primary in SSTC
[Solid State Tesla Coils (SSTC)]
davekni
June 07, 2024, 06:42:26 AM
post Re: Space-X Starship test this week
[Science, Research and News In Other Fields Than Electronics]
MRMILSTAR
June 07, 2024, 05:08:00 AM
post Re: Half bridge sstc different waveform on two mosfets
[Solid State Tesla Coils (SSTC)]
davekni
June 07, 2024, 03:16:31 AM
post Re: Space-X Starship test this week
[Science, Research and News In Other Fields Than Electronics]
klugesmith
June 06, 2024, 11:37:20 PM
post Adding capacitor to primary in SSTC
[Solid State Tesla Coils (SSTC)]
Simranjit
June 06, 2024, 11:20:23 PM
post Re: Plasma Torid - Class E Self Resonant Dual/Stereo - Plasma Torid Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
June 06, 2024, 10:54:48 PM
post Re: Half bridge sstc different waveform on two mosfets
[Solid State Tesla Coils (SSTC)]
ZakW
June 06, 2024, 05:17:02 AM
post Re: Half bridge sstc different waveform on two mosfets
[Solid State Tesla Coils (SSTC)]
Simranjit
June 06, 2024, 04:50:00 AM
post Re: Half bridge sstc different waveform on two mosfets
[Solid State Tesla Coils (SSTC)]
davekni
June 06, 2024, 04:00:52 AM
post Re: Half bridge sstc different waveform on two mosfets
[Solid State Tesla Coils (SSTC)]
ZakW
June 06, 2024, 01:43:41 AM
post Re: Half bridge sstc different waveform on two mosfets
[Solid State Tesla Coils (SSTC)]
Simranjit
June 05, 2024, 11:11:17 PM
post Re: Half bridge sstc different waveform on two mosfets
[Solid State Tesla Coils (SSTC)]
Michelle_
June 05, 2024, 10:18:57 PM
post Re: Half bridge sstc different waveform on two mosfets
[Solid State Tesla Coils (SSTC)]
Simranjit
June 05, 2024, 10:13:03 PM
post Re: Half bridge sstc different waveform on two mosfets
[Solid State Tesla Coils (SSTC)]
ZakW
June 05, 2024, 09:29:18 PM
post Half bridge sstc different waveform on two mosfets
[Solid State Tesla Coils (SSTC)]
Simranjit
June 05, 2024, 08:46:53 PM
post Re: Want to build HV HF oscilloscope probe.
[Electronic Circuits]
Twospoons
June 05, 2024, 07:04:45 AM
post Re: Want to build HV HF oscilloscope probe.
[Electronic Circuits]
Domo
June 05, 2024, 04:58:35 AM
post Re: Pearson current monitor model 1330 teardown (100kA)
[Laboratories, Equipment and Tools]
klugesmith
June 05, 2024, 01:42:04 AM
post Re: Coulometric hourmeters
[Laboratories, Equipment and Tools]
klugesmith
June 04, 2024, 10:31:58 PM
post Re: My completed 14-stage Cockroft-Walton voltage multiplier
[Voltage Multipliers]
pete_dl
June 04, 2024, 08:08:28 PM
post Re: Want to build HV HF oscilloscope probe.
[Electronic Circuits]
Twospoons
June 03, 2024, 11:13:26 PM
post Re: First DRSSTC questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
June 03, 2024, 10:35:57 PM
post Re: First DRSSTC questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Hi-Deff
June 03, 2024, 05:51:05 PM
post Re: Want to build HV HF oscilloscope probe.
[Electronic Circuits]
Domo
June 03, 2024, 07:41:41 AM
post Re: First DRSSTC questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
June 03, 2024, 05:28:44 AM
post Re: RDRSSTC - Project Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
June 03, 2024, 05:02:19 AM
post Re: First DRSSTC questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
June 03, 2024, 03:47:33 AM
post Re: First DRSSTC questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
June 03, 2024, 02:23:58 AM
post Re: First DRSSTC questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Hi-Deff
June 03, 2024, 01:25:24 AM
post Re: RDRSSTC - Project Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ZakW
June 03, 2024, 01:08:47 AM
post Re: RDRSSTC - Project Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
June 02, 2024, 10:29:02 PM
post Re: Steve Ward SSTC5 build
[Solid State Tesla Coils (SSTC)]
Michelle_
June 02, 2024, 10:02:45 PM
post Re: Racing sparks
[Spark Gap Tesla Coils (SGTC)]
davekni
June 02, 2024, 08:25:37 PM
post Re: Steve Ward SSTC5 build
[Solid State Tesla Coils (SSTC)]
Michelle_
June 02, 2024, 04:51:58 PM
post Re: RDRSSTC - Project Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Michelle_
June 02, 2024, 04:44:30 PM
post Re: My completed 14-stage Cockroft-Walton voltage multiplier
[Voltage Multipliers]
MRMILSTAR
June 02, 2024, 03:25:11 PM
post APC Smart-UPS 1500VA Teardown
[Electronic Circuits]
Mads Barnkob
June 02, 2024, 01:36:11 PM
post Re: My completed 14-stage Cockroft-Walton voltage multiplier
[Voltage Multipliers]
pete_dl
June 02, 2024, 11:43:40 AM
post Re: RDRSSTC - Project Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ZakW
June 02, 2024, 08:49:11 AM
post Re: RDRSSTC - Project Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
June 02, 2024, 08:36:07 AM
post Re: RDRSSTC - Project Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ZakW
June 02, 2024, 12:41:50 AM
post Re: Steve Ward SSTC5 build
[Solid State Tesla Coils (SSTC)]
Benjamin Lockhart
June 01, 2024, 08:24:35 PM
post Pearson current monitor model 1330 teardown (100kA)
[Laboratories, Equipment and Tools]
Mads Barnkob
June 01, 2024, 08:22:28 PM
post Re: Steve Ward SSTC5 build
[Solid State Tesla Coils (SSTC)]
Michelle_
June 01, 2024, 03:56:53 AM
post Re: Racing sparks
[Spark Gap Tesla Coils (SGTC)]
Terry
June 01, 2024, 12:03:50 AM
post Re: First DRSSTC questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Hi-Deff
May 31, 2024, 11:46:20 PM
post Re: Steve Ward SSTC5 build
[Solid State Tesla Coils (SSTC)]
Michelle_
May 31, 2024, 06:13:59 PM
post Re: First DRSSTC questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
May 31, 2024, 01:55:22 AM
post Re: First DRSSTC questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
May 30, 2024, 11:57:49 PM
post Re: First DRSSTC questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
May 30, 2024, 11:50:06 PM
post First DRSSTC questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Hi-Deff
May 30, 2024, 11:23:35 PM
post Re: Steve Ward SSTC5 build
[Solid State Tesla Coils (SSTC)]
davekni
May 30, 2024, 10:43:06 PM
post Re: Benjamin's DRSSTC3
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
May 30, 2024, 10:24:35 PM
post Re: SSTC tripping circuit breaker
[Solid State Tesla Coils (SSTC)]
NyaaX_X
May 30, 2024, 06:10:04 PM
post Re: SSTC tripping circuit breaker
[Solid State Tesla Coils (SSTC)]
Simranjit
May 30, 2024, 04:56:11 PM
post Re: SSTC tripping circuit breaker
[Solid State Tesla Coils (SSTC)]
Michelle_
May 30, 2024, 04:48:05 PM
post Re: Steve Ward SSTC5 build
[Solid State Tesla Coils (SSTC)]
Michelle_
May 30, 2024, 04:37:22 PM
post Re: SSTC tripping circuit breaker
[Solid State Tesla Coils (SSTC)]
klugesmith
May 30, 2024, 04:16:31 PM
post Re: SSTC tripping circuit breaker
[Solid State Tesla Coils (SSTC)]
NyaaX_X
May 30, 2024, 03:34:10 PM
post Re: SSTC tripping circuit breaker
[Solid State Tesla Coils (SSTC)]
Simranjit
May 30, 2024, 02:53:50 PM
post Re: SSTC tripping circuit breaker
[Solid State Tesla Coils (SSTC)]
NyaaX_X
May 30, 2024, 12:44:47 PM
post SSTC tripping circuit breaker
[Solid State Tesla Coils (SSTC)]
Simranjit
May 30, 2024, 07:52:56 AM
post Re: Steve Ward SSTC5 build
[Solid State Tesla Coils (SSTC)]
NyaaX_X
May 30, 2024, 07:07:53 AM
post Re: Benjamin's DRSSTC3
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
May 30, 2024, 07:04:40 AM
post Re: Steve Ward SSTC5 build
[Solid State Tesla Coils (SSTC)]
Michelle_
May 30, 2024, 05:16:50 AM
post Re: Steve Ward SSTC5 build
[Solid State Tesla Coils (SSTC)]
Michelle_
May 30, 2024, 05:08:17 AM
post Re: Steve Ward SSTC5 build
[Solid State Tesla Coils (SSTC)]
davekni
May 30, 2024, 04:29:30 AM
post Re: Benjamin's DRSSTC3
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
May 30, 2024, 03:52:36 AM
post Re: Racing sparks
[Spark Gap Tesla Coils (SGTC)]
davekni
May 30, 2024, 03:47:12 AM
post Re: Steve Ward SSTC5 build
[Solid State Tesla Coils (SSTC)]
Benjamin Lockhart
May 30, 2024, 03:41:34 AM
post Re: Steve Ward SSTC5 build
[Solid State Tesla Coils (SSTC)]
Michelle_
May 30, 2024, 03:27:28 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