Caman, tnx for your answer, i would be most interrested in non metallized safe film thicknes required for something around 400Vdc of polyroyleene in respect to polystyrene and polyester.
Offcourse there will be also differencies between foils from different manufacturers, but in general, could you give me some used single layer thicknesses when used with aluminiumfoil (airockets) and theyr used rated Vdc of some of those materials?
Offcourse there will be also differencies between foils from different manufacturers, but in general, could you give me some used single layer thicknesses when used with aluminiumfoil (airockets) and theyr used rated Vdc of some of those materials?
BOPP (Polypropylene) vs PE (Polyester), BOPP has a higher with stand. Like I mentioned, application (is it actually DC, is there a ripple, or is it AC and what freq), as well as operating temp plays a very important part. 400VDC with a good quality foil, 5 or 6 um would be adequate, depending on the circumstance. One of the issues is material handling (film and/or foil). Any stretching, particulate, or poorly slit foil will effect the withstand.
Tnx Capman, good to know.
This time, application would be audiofrquency range, but actually only the 300Vdc between two polyester isolated bifilar wound wires.
For polyester you propably ment PET, PE was always polyethylene for me, as was PP for polypropyleene, could you please tell me what the prefix BO stand for?
Till now, i never needed to know anything deeper about polyester, and i have only expirience with lowish capacitance high voltage rf bypass caps, made of alu plates and teflon sheets.
Only once i used polpropylene do to practical reasons (huge variable cap, to replace a vacuum cap ). I Had also the idea of using multiple layers once (because sheets can have tiny, tyni holes in them) but i rejected that idea because the highly static surfaces would be impossible to keep clean, and on top, the practically unavoidable airpockets. Would you know how that airpocket prob is solved in commercially made, just rolled up, film/foil caps ?
This time, application would be audiofrquency range, but actually only the 300Vdc between two polyester isolated bifilar wound wires.
For polyester you propably ment PET, PE was always polyethylene for me, as was PP for polypropyleene, could you please tell me what the prefix BO stand for?
Till now, i never needed to know anything deeper about polyester, and i have only expirience with lowish capacitance high voltage rf bypass caps, made of alu plates and teflon sheets.
Only once i used polpropylene do to practical reasons (huge variable cap, to replace a vacuum cap ). I Had also the idea of using multiple layers once (because sheets can have tiny, tyni holes in them) but i rejected that idea because the highly static surfaces would be impossible to keep clean, and on top, the practically unavoidable airpockets. Would you know how that airpocket prob is solved in commercially made, just rolled up, film/foil caps ?
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Multi thin layers is always better. Air pockets are not really a problem until you get into high DC voltage, above 20KV, or AC voltage that can produce corona. Corona, sustained, can erode the dielectric, thus leading to failure. Film capacitor winders use state of the art tensioning, often combined with a lay-on roller to produce a roll (aka winding) with very little air. If its going to be used in HV, they are impregnated.
Yes, actually polyester is PET, but we often shorten it to PE (or sometimes MY), and we don't use polyethylene, so there is no confusion in our industry. DuPont has been putting pressure on people and companies for using the trade names, so we drop the Mylar from most of our documents. BOPP is the acronym for Biaxially Oriented Polypropylene, which related to how it is manufactured.
Yes, actually polyester is PET, but we often shorten it to PE (or sometimes MY), and we don't use polyethylene, so there is no confusion in our industry. DuPont has been putting pressure on people and companies for using the trade names, so we drop the Mylar from most of our documents. BOPP is the acronym for Biaxially Oriented Polypropylene, which related to how it is manufactured.
Tnx Capman.
I had a case where the factory bosses decided (again) to ramp up production. That needed more power, bigger transformer, bigger air/water heat exchanger, rectifier stack a.s.o, all had to be cramped into the same old powersupply cabinet (originally designed for 150kVA, then propped up to 200, now propped even more) and stuff got just to close to the cabinet walls and doors.
Covering the most problematic areas with PE sheets helped to prevent the otherwise destructiv flashes, but do to the Dk dependend, unfortune voltage distribution between air and the pe sheets with higher Dk some low power discharges still left some black marks at the air/sheet interface.
Interrestingly, only the air/pe sheet interface had suffered from what where clearly low energy discharges, no sign of any discharge could be found at the transformer or anywhere else (3ph, 9.6kV,250kVA).
I had a case where the factory bosses decided (again) to ramp up production. That needed more power, bigger transformer, bigger air/water heat exchanger, rectifier stack a.s.o, all had to be cramped into the same old powersupply cabinet (originally designed for 150kVA, then propped up to 200, now propped even more) and stuff got just to close to the cabinet walls and doors.
Covering the most problematic areas with PE sheets helped to prevent the otherwise destructiv flashes, but do to the Dk dependend, unfortune voltage distribution between air and the pe sheets with higher Dk some low power discharges still left some black marks at the air/sheet interface.
Interrestingly, only the air/pe sheet interface had suffered from what where clearly low energy discharges, no sign of any discharge could be found at the transformer or anywhere else (3ph, 9.6kV,250kVA).
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Sorry for hijacking this old thread.
I have 8 of theese capacitors as shown in photo, and I would like to use them in a p3a running just 35v.
I have tested them and they read above rated uf ,and very low esr, so I think they are usable.
I got them because I bought a dead diy amplifier, just needed chassis.
I have been unable to find any info on them at all, anyone here know theese?
The have screw terminal and are large for their rating.
I have 8 of theese capacitors as shown in photo, and I would like to use them in a p3a running just 35v.
I have tested them and they read above rated uf ,and very low esr, so I think they are usable.
I got them because I bought a dead diy amplifier, just needed chassis.
I have been unable to find any info on them at all, anyone here know theese?
The have screw terminal and are large for their rating.