VTTC Capacitor Suitibility
Kolas, Tue Jul 25 2006, 10:43PMWell there is a LOT fo talk about VTTC's lately, wierd.
ive been sitting on these caps for a while.
two pics
name plate reads as follows:
Lepel HF Laboratories
SN 5-6555
type .0055
KVA 1500
Volts 9000
Amps 200
Freq. 540
Anway, I guess I know that these are good caps; they all read 6nF.
What worries me is the freq, it's only 540, though I don't know what order of measurement that is.
Anyway they were used in an induction heater. Which used that triode I have, in what apeared to be an armstrong circuit.
Power supply was a full wave rectified 5kV three phase transformer.
Any thoughts are much apreciated, thank you.
Kolas
Re: VTTC Capacitor Suitibility
Marko, Tue Jul 25 2006, 10:50PM
If they were really used in induction heater, and that this rating is for 540kHz I'd say they are OK.
Good luck then with probably largest 'known' CW coils 'around there
Marko, Tue Jul 25 2006, 10:50PM
If they were really used in induction heater, and that this rating is for 540kHz I'd say they are OK.
Good luck then with probably largest 'known' CW coils 'around there
Re: VTTC Capacitor Suitibility
Steve Ward, Tue Jul 25 2006, 11:29PM
Using ohms law and the impedance of the capacitor you can figure out if they mean 540hz or otherwise. Given that its reactance at 540hz is nearly 50k ohms, you would only get .18Apk through it at 9000Vpk AC sine wave (far from the 200A rating). At 540khz, the reactance is about 50 ohms, so at 9kvpk AC, you would get 180Apk, much closer to the 200A rating. I would guess this means its rated for this frequency.
You have rather extraordinary capacitors there, i hope you do something great with them.
As to VTTC suitability. I would think that the tank Q is not likely to exceed about 10 or so, so the tank current might be 10X the average input current (rough figures here). So you would probably have to feed the coil 20A input current before exceeding the current rating of just 1 capacitor. Its likely you would over-volt one before that happened. I would definately series those caps up, and be careful. It might be worth installing some sort of voltage probe to be sure you dont kill those caps.
Steve Ward, Tue Jul 25 2006, 11:29PM
Using ohms law and the impedance of the capacitor you can figure out if they mean 540hz or otherwise. Given that its reactance at 540hz is nearly 50k ohms, you would only get .18Apk through it at 9000Vpk AC sine wave (far from the 200A rating). At 540khz, the reactance is about 50 ohms, so at 9kvpk AC, you would get 180Apk, much closer to the 200A rating. I would guess this means its rated for this frequency.
You have rather extraordinary capacitors there, i hope you do something great with them.
As to VTTC suitability. I would think that the tank Q is not likely to exceed about 10 or so, so the tank current might be 10X the average input current (rough figures here). So you would probably have to feed the coil 20A input current before exceeding the current rating of just 1 capacitor. Its likely you would over-volt one before that happened. I would definately series those caps up, and be careful. It might be worth installing some sort of voltage probe to be sure you dont kill those caps.
Re: VTTC Capacitor Suitibility
Marko, Tue Jul 25 2006, 11:35PM
Or if i'm simply too lazy to calculate, I can simply say both 540Hz or 540Mhz ratings would be unrealistic enough.
It seems that capacitors are to be used with machlett labs ML-6696 100kW @40Mhz triode
from the topic
Makes a nice little VTTC, but unfortunately power company has put it's limits :/
Marko, Tue Jul 25 2006, 11:35PM
Or if i'm simply too lazy to calculate, I can simply say both 540Hz or 540Mhz ratings would be unrealistic enough.
It seems that capacitors are to be used with machlett labs ML-6696 100kW @40Mhz triode
from the topic
Makes a nice little VTTC, but unfortunately power company has put it's limits :/
Re: VTTC Capacitor Suitibility
Steve Conner, Wed Jul 26 2006, 12:09AM
Wow, awesome caps! Can you see any hose barbs on them for water cooling? Having said that, they're rated at a crazy 1500kVA. So at a tank Q of 10 like Ward suggested, you'll need more than 150kW from the power company to overload one of those caps. Even at a Q of 100, it could take 15kW, and a Tesla coil won't have a Q that high unless it's mistuned so badly that it doesn't break out.
Steve Conner, Wed Jul 26 2006, 12:09AM
Wow, awesome caps! Can you see any hose barbs on them for water cooling? Having said that, they're rated at a crazy 1500kVA. So at a tank Q of 10 like Ward suggested, you'll need more than 150kW from the power company to overload one of those caps. Even at a Q of 100, it could take 15kW, and a Tesla coil won't have a Q that high unless it's mistuned so badly that it doesn't break out.
Re: VTTC Capacitor Suitibility
Kolas, Wed Jul 26 2006, 01:47AM
Hah! I'm loving what I hear.
I did want to try a sitiation where a break out point isn't used, at what cost would that be to these caps?
No the caps arent water cooled.
Each one is about the size of a standard computer tower, (mini tower?) and they are filled with oil. (presumabally PCB oil O_O)
Case is made from alluminum.
Kolas
Kolas, Wed Jul 26 2006, 01:47AM
Hah! I'm loving what I hear.
I did want to try a sitiation where a break out point isn't used, at what cost would that be to these caps?
No the caps arent water cooled.
Each one is about the size of a standard computer tower, (mini tower?) and they are filled with oil. (presumabally PCB oil O_O)
Case is made from alluminum.
Kolas
Re: VTTC Capacitor Suitibility
Vaxian, Wed Apr 11 2007, 08:55AM
I find myself wondering where I can find a junked induction heater, those are some BEEFY caps!
Vaxian, Wed Apr 11 2007, 08:55AM
I find myself wondering where I can find a junked induction heater, those are some BEEFY caps!
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