I work for a very large science museum. Our 'science show' division would like to install a large Tesla coil in a small theater we use for physics and chemistry shows. The theater measures 40' wide, 60 veet long, and perhaps 40' in height. The audience sits on aluminum bleachers on steep risers, about 20 feet from the stage.
A Tesla coil is a tuned rf transformer with a very high turns ratio. The primary coil is supplied by an oscillator, about 100kHz, and the secondary coil steps this up to voltages that range from 100kV to 1MV. The field intensity is very high at the secondary coil's terminal. This causes the air to break down in the vicinity and thus produces very large luminous streamers that radiate in all directions. The streamer current is very low, though it will cause local heating at the point of attachment. The high frequency assures that the capacitive impedance to earth from any metal object is quite low. Therefore, the arc will readily attach to most metallic objects in the vicinity.
Several of our maintenance people object to the installation of this device, citing possible damage to data cables and electronic equipment. My contention is that only light shielding--e.g., a large cube of chicken wire, will give complete protection to the data lines. There's also concern that the device may present a raspy load to the power line, thus causing havoc in attached equipment. It doesn't help that one of the old galleries is being converted to a radio/TV broadcast complex, though that equipment will be at the other end of our 1000-foot-long building. My only adverse encounter with our small Tesla coils is that sometimes they'll reset my digital watch to January 1, 12:01am.
If anyone has any experience with the bonding, grounding, power-line filtering, or other lore on Tesla coil installations we will be most grateful.
Mark Kinsler
COSI-Columbus, Ohio
A Tesla coil is a tuned rf transformer with a very high turns ratio. The primary coil is supplied by an oscillator, about 100kHz, and the secondary coil steps this up to voltages that range from 100kV to 1MV. The field intensity is very high at the secondary coil's terminal. This causes the air to break down in the vicinity and thus produces very large luminous streamers that radiate in all directions. The streamer current is very low, though it will cause local heating at the point of attachment. The high frequency assures that the capacitive impedance to earth from any metal object is quite low. Therefore, the arc will readily attach to most metallic objects in the vicinity.
Several of our maintenance people object to the installation of this device, citing possible damage to data cables and electronic equipment. My contention is that only light shielding--e.g., a large cube of chicken wire, will give complete protection to the data lines. There's also concern that the device may present a raspy load to the power line, thus causing havoc in attached equipment. It doesn't help that one of the old galleries is being converted to a radio/TV broadcast complex, though that equipment will be at the other end of our 1000-foot-long building. My only adverse encounter with our small Tesla coils is that sometimes they'll reset my digital watch to January 1, 12:01am.
If anyone has any experience with the bonding, grounding, power-line filtering, or other lore on Tesla coil installations we will be most grateful.
Mark Kinsler
COSI-Columbus, Ohio
