Re: question about driving a DC sync spark gap

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Esondrmn@xxxxxxx 

In a message dated 10/11/2006 8:19:28 PM Pacific Daylight Time, 
tesla@xxxxxxxxxx writes:
Dear All,

Is anyone using a DC motor to drive an async rotary spark gap? If anyone is
doing this, how is your variable DC power supply built? We are having
consistent CATESTROPHIC failure of the power supply diodes. Not the motor.
The motor is always fine, and the variac is always fine. We are using huge
giant diodes (300V @400A) and they are frying instantly. We have tried
chokes in series, caps in parallel, caps in series, but nothing seems to
help.

Please help before we shoot the DC motor with a 1000 watt CO2 laser, and
rebuild our spark gap using a variable AC motor.

Background:. This is an 11" OD coil 57" tall #18 wire, 15kva pig, 11 to 15
foot arcs.

I have used a variable speed motor to run an async rotary gap.  It 
was a series wound motor (similar to an old sewing machine motor but 
much larger).  Just connect the field and armature windings in series 
and use a variac - running off AC, no diodes required.

Ed Sonderman