Dear Dick,
spark gaps are a genuine way of measuring high voltages in a HV-Laboratory. There exist tables for DC and AC 50 Hz. Spark gaps must be used, as it is impossible to use a rotary swich in a meter at 100kV or more. oen of the spheres is doped with an radioactive element to cause discharge always at the same place on the spheres surface. Break down voltage is checked with observers eye and ears and depends on Voltage (ac/dc, HF), temperature, humidity and absolute air pressure. An uncertainity of about +-2% may be obtained in voltage-measurements. A gross value for break down voltage is 30 kV/cm. Try to get into contact with an advanced engineering school teaching energy technics, machine engineering and High frequency technics. If the schools is specialized on contemporary data processing, electronics and international economy, You are wrong, so an traditional institution is recommended. In my case it is "Georg-Simon-Ohm-Fachhochschule Nürnberg".
73,
Hans-Albrecht
DK 8 ND
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Von: [email protected]
Gesendet: 10.03.05 20:51:22
An: "Hans-Albrecht Haffa" <[email protected]>
Betreff: Re: LF: Off topic
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Hi Dick Looking in my trusty "Reference Data for Radio Engineers" (won in a rally raffle at least 40 years ago !) the spark gap voltages chart indicates about 30 kV per inch for "needles" and between 55 and 80 kV for spheres spaced and inch apart (depending on the size of the spheres). Hope that helps. TYo All from PA0SE
I am presently writing an article for our VERON magazine Electron on the early radio experiments by Marconi. In these experiments spark gaps played an important role. Because I would like to perform some simple calculations on the peak power radiated by a spark transmitter I am looking for data on the break down voltage of spark gaps, consisting of two spheres.
In literature, found on the Internet, 75kV/inch is quoted but it is not stated whether this is between points or spheres and that makes a lot of difference.
Temperature and air pressure also influence break down voltage but I will forget about that, reckoning with "normal" conditions of,
say , 20 degrees centigrade and 1000 hectopascal or whatever as reckoned as standard barometric pressure.
Your help will be very much appreciated.
73, Dick, PA0SE
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