Eurofarad caps for MMC?
RickR, Thu Aug 25 2011, 07:32PMWell, it'd be difficult to call it a MMC with these caps, more like an MC.
Anyway, I was looking at some Eurofarad capacitors available on eBay. These appear to be very beefy caps that, properly hooked together, *might* be useful for a DRSSTC tank. They weigh in at 3.75 uF, 580V(rms), 152 Amps (I'm assuming at their rated voltage).
Here's the link
Others here have referred to these as snubbers, and they certainly look like they might be, but I'm worried that they might just be some exotic type of filter cap with poor pulse characteristics.
Does anybody have any additional information about these caps? I've tried Google to no avail.
I'd be interested in anyone's opinion about using these as tank caps for a medium-large DRSSTC.
Thanks,
Rick
Re: Eurofarad caps for MMC?
Dr. ISOTOP, Thu Aug 25 2011, 08:08PM
They only make sense for a large DRSSTC, though. Even with ten in series (which should be enough), you still have a 375 nF MMC.
Dr. ISOTOP, Thu Aug 25 2011, 08:08PM
RickR wrote ...
Well, it'd be difficult to call it a MMC with these caps, more like an MC.
Anyway, I was looking at some Eurofarad capacitors available on eBay. These appear to be very beefy caps that, properly hooked together, *might* be useful for a DRSSTC tank. They weigh in at 3.75 uF, 580V(rms), 152 Amps (I'm assuming at their rated voltage).
Here's the link
Others here have referred to these as snubbers, and they certainly look like they might be, but I'm worried that they might just be some exotic type of filter cap with poor pulse characteristics.
Does anybody have any additional information about these caps? I've tried Google to no avail.
I'd be interested in anyone's opinion about using these as tank caps for a medium-large DRSSTC.
Thanks,
Rick
I've run them to 4KVA (apparent input, not reactive, power) in my induction heater with only mild heating. I think in their former life, these were GTO snubbers. Should be fine for a DRSSTC...judging from Eurofarad's GTO snubber ratings, this thing should have a ~2KVDC rating.Well, it'd be difficult to call it a MMC with these caps, more like an MC.
Anyway, I was looking at some Eurofarad capacitors available on eBay. These appear to be very beefy caps that, properly hooked together, *might* be useful for a DRSSTC tank. They weigh in at 3.75 uF, 580V(rms), 152 Amps (I'm assuming at their rated voltage).
Here's the link
Others here have referred to these as snubbers, and they certainly look like they might be, but I'm worried that they might just be some exotic type of filter cap with poor pulse characteristics.
Does anybody have any additional information about these caps? I've tried Google to no avail.
I'd be interested in anyone's opinion about using these as tank caps for a medium-large DRSSTC.
Thanks,
Rick
They only make sense for a large DRSSTC, though. Even with ten in series (which should be enough), you still have a 375 nF MMC.
Re: Eurofarad caps for MMC?
RickR, Thu Aug 25 2011, 08:26PM
Thanks bwang, yours was the post I was referring to. Do you have any additional info on these things other than what was on the eBay page?
Rick
RickR, Thu Aug 25 2011, 08:26PM
Thanks bwang, yours was the post I was referring to. Do you have any additional info on these things other than what was on the eBay page?
Rick
Re: Eurofarad caps for MMC?
Kizmo, Fri Nov 11 2011, 07:14PM
I murdered one of these capacitos in the name of science.
Firt thing was overvoltage stress test. Since only RMS voltage was given, i wanted to test how high DC voltage these could stand. Guestimation from other snubber capacitor datasheets gave me values from 900VDC to 1300VDC
So i hooked up simple test setup: variac, rectified NST and HV meter:
500V... 1000V... 1500V.. SNAP.. 1600V... 2000V... 2200V SNAP SNAP POP ok :)
Judging from that i would say absolute maximum DC voltage is 1kV
Now lets pop it open. Hacksaw cuts easily through fibre glass.
Outer shell was very well glued. Couple teespoons of odorless mineral oil came out
Terminal plate was soldered on sprayed metal. It required quite a bit of hammering.
They see me unrollin', they hatin
Foil separated from metallized film. Construction is identical compared to CDE942 series capacitors.
I unrolled maybe 15 meters of this stuff and found couple self healing spots like one in picture. All at the edge of the foil as usual. Rest of the film looked really good
I made a mess
So, what did we learn from this? Well, these eurofarad capacitors are Metallized film-foil hybrids just like CDE942 series. They are oil impregnated. Foil edges are bonded together with spray metal and terminals to spray metal with heavy soldering.
Just respect the voltage ratings and there is no reason what so ever why these would not work in any kind of tesla coil! :)
Kizmo, Fri Nov 11 2011, 07:14PM
I murdered one of these capacitos in the name of science.
Firt thing was overvoltage stress test. Since only RMS voltage was given, i wanted to test how high DC voltage these could stand. Guestimation from other snubber capacitor datasheets gave me values from 900VDC to 1300VDC
So i hooked up simple test setup: variac, rectified NST and HV meter:
500V... 1000V... 1500V.. SNAP.. 1600V... 2000V... 2200V SNAP SNAP POP ok :)
Judging from that i would say absolute maximum DC voltage is 1kV
Now lets pop it open. Hacksaw cuts easily through fibre glass.
Outer shell was very well glued. Couple teespoons of odorless mineral oil came out
Terminal plate was soldered on sprayed metal. It required quite a bit of hammering.
They see me unrollin', they hatin
Foil separated from metallized film. Construction is identical compared to CDE942 series capacitors.
I unrolled maybe 15 meters of this stuff and found couple self healing spots like one in picture. All at the edge of the foil as usual. Rest of the film looked really good
I made a mess
So, what did we learn from this? Well, these eurofarad capacitors are Metallized film-foil hybrids just like CDE942 series. They are oil impregnated. Foil edges are bonded together with spray metal and terminals to spray metal with heavy soldering.
Just respect the voltage ratings and there is no reason what so ever why these would not work in any kind of tesla coil! :)
Re: Eurofarad caps for MMC?
RickR, Fri Nov 11 2011, 07:58PM
Hey Kizmo,
Thanks for actually jumping in there and doing the experimental research! That's really useful information. I ended up buying 20 of these on the speculation that they'd be useful in a large DRSSTC. I haven't gotten to the point of using them yet, but your research indicates that they ought to perform well.
Thanks again,
Rick
RickR, Fri Nov 11 2011, 07:58PM
Hey Kizmo,
Thanks for actually jumping in there and doing the experimental research! That's really useful information. I ended up buying 20 of these on the speculation that they'd be useful in a large DRSSTC. I haven't gotten to the point of using them yet, but your research indicates that they ought to perform well.
Thanks again,
Rick
Re: Eurofarad caps for MMC?
Kizmo, Fri Nov 11 2011, 08:21PM
Thanks :)
I have pile of these too and was wondering same thing.
Maybe next step of my more or less destructive testing is to put another cap in drsstc circuit and crank it up untill it starts popping (self healed flashover from peak voltage)
I have done this before with dry resin film caps, its very easy to hear and shouldnt hurt the capacitor too badly since its self healing type
Kizmo, Fri Nov 11 2011, 08:21PM
Thanks :)
I have pile of these too and was wondering same thing.
Maybe next step of my more or less destructive testing is to put another cap in drsstc circuit and crank it up untill it starts popping (self healed flashover from peak voltage)
I have done this before with dry resin film caps, its very easy to hear and shouldnt hurt the capacitor too badly since its self healing type
Re: Eurofarad caps for MMC?
Kizmo, Sat Nov 12 2011, 09:16PM
If you want to drill/tap holes this will help. Brass piece is 7mm thick, original M6 thread was made 6.5mm deep
Kizmo, Sat Nov 12 2011, 09:16PM
If you want to drill/tap holes this will help. Brass piece is 7mm thick, original M6 thread was made 6.5mm deep
Re: Eurofarad caps for MMC?
Marko, Tue Dec 06 2011, 08:54PM
Hey guys
I see some of you are from europe, where exactly do you get the piles of these pretty caps?
They are very cheap on ebay but shipping to europe would be complicated.
Anyone happens to have one of those 100uF, 500A versions of those caps? I need one for an experiment :)
Marko
Marko, Tue Dec 06 2011, 08:54PM
Hey guys
I see some of you are from europe, where exactly do you get the piles of these pretty caps?
They are very cheap on ebay but shipping to europe would be complicated.
Anyone happens to have one of those 100uF, 500A versions of those caps? I need one for an experiment :)
Marko
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