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Click on the photos for bigger picture. |
| My synchronous rotary spark gap is my own 3000RPM-version of Finn
Hammer's very successful 1500RPM "Millenium-Gap" design. It has been
realized by "Lehrwerkstaette fuer Mechaniker"(LW), Basel, in a very cooperative
way: Mr. Bader, chief engineer of the workshop, not only helped me to set
the tolerances, but also managed to realize the gap, in time, for the "Technorama"
show of Tesla coil B&W. The gap, beeing a great success in the whole,
suffered a few serious beginner's mistakes:
- The motor choosen was a very cheap 400W double-grinder motor, whose mechanical imprecision brought a hassle for reassembling, after having filed flats, in order to get it sync. It's only getting sync now, by use of a variac power supply, which, on the positive side, allows a modest setting of the phase-angle, by electrical means ( ~10 degrees). - I got nasty carbon tracking along the surfaces of the hardpaper (~pertinax) mounting supports, 'cause of too short insulating paths.(see the pictures!). The rule of thumb "surface path = ~ 3 times the path in air" should be taken seriously! By good luck, the construction could easily be modified, by cleaning and epoxying insulating bars at the critical places of the gap. ( The HV was coming from my 16kV (RMS) -PT's, and might have been about 25..30kV peak, considering some resonant rise.) |
SRSG, view from top. Rotor d = 240mm 10mm diam. tungsten electrodes @ d=215mm 47'709 bytes |
Side view... sorry for pic quality :-( 34'456 bytes |
Carbon track 1 30mm wide...,on top, between HV supports 38'574 bytes |
Carbon track 2: 50mm wide, hidden between baseplates. (look at screws..!) 44'461 bytes |
Insulating bars, hopefully preventing new carbon tracks. 28'862 bytes |
Another perspective. 23'383 bytes |
SRSG, buildt into base of B&W; view from "service side" of TC. 86'479 bytes |
Side view, same... 74'082 bytes |
| . | . | . | . |
| Following are three
snapshots of Martin Damev's ASRSG. |
47'451 bytes |
39'320 bytes |
fired in Technorama with B&W-TC 17'823 bytes |
| . | . | . | . |
| Modifying the
armature of my 400W double-grinder motor for sync operation, by filing two flats >>> |
Motor disassembled 59'940 bytes |
Armature with 25.5mm wide flat 17'635 bytes |
The flats seem to
be just a little above optimum: 24.5mm was slightly better, regarding torque |