Metallized polyester capacitors for marx duty.
Wolfram, Thu Feb 08 2007, 07:46AMI have acquired some 16kV 20nF metallized polyester caps. I have not been able to find any data on them, but similar caps from the same manufacturer (ASC) have a peak current rating of only around 10A. Are these caps OK for marx duty, or do they most likely have too high ESR/ESL?
Anders M.
Re: Metallized polyester capacitors for marx duty.
thedatastream, Thu Feb 08 2007, 08:12AM
I used PE film caps in my small Marx
with no problems. Why not build a 1 or 2 stage Marx and run it for a while to judge the performance?
James
thedatastream, Thu Feb 08 2007, 08:12AM
I used PE film caps in my small Marx
with no problems. Why not build a 1 or 2 stage Marx and run it for a while to judge the performance?James
Re: Metallized polyester capacitors for marx duty.
Dr. Slack, Thu Feb 08 2007, 08:45AM
It depends what you want to use your marx for.
If you are using it to create transients with a known source impedance and reproducible shape for testing commercial HV transmission components, then you would have to control the series connection of all the ESL/ESRs to be substantially less than your target source impedance. It's quite interesting to read the technical specs and background of such marx generators, their shaping networks, some even build capacitors out of lengths of 50ohm cable to get a known duration discharge and accurate output impedance.
However, if you want sparks, especially spark length, it matters not a jot.
Dr. Slack, Thu Feb 08 2007, 08:45AM
It depends what you want to use your marx for.
If you are using it to create transients with a known source impedance and reproducible shape for testing commercial HV transmission components, then you would have to control the series connection of all the ESL/ESRs to be substantially less than your target source impedance. It's quite interesting to read the technical specs and background of such marx generators, their shaping networks, some even build capacitors out of lengths of 50ohm cable to get a known duration discharge and accurate output impedance.
However, if you want sparks, especially spark length, it matters not a jot.
Re: Metallized polyester capacitors for marx duty.
Steve Ward, Thu Feb 08 2007, 08:48PM
With only a 10A rating, you might need a series resistor, making the output sparks less than exciting. I really find the 10A rating puzzling though... its really small.
Steve Ward, Thu Feb 08 2007, 08:48PM
With only a 10A rating, you might need a series resistor, making the output sparks less than exciting. I really find the 10A rating puzzling though... its really small.
Re: Metallized polyester capacitors for marx duty.
Wolfram, Thu Feb 08 2007, 10:43PM
What would happen without the series resistors?
Here is a datasheet for some different caps from the same manufacturer, those were the only 16kV types that I found the datasheet for. This is where I got the peak current figure.
Wolfram, Thu Feb 08 2007, 10:43PM
What would happen without the series resistors?
Here is a datasheet for some different caps from the same manufacturer, those were the only 16kV types that I found the datasheet for. This is where I got the peak current figure.
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