Gap voltages AC vs. DC

From: 	Adam[SMTP:absmith-at-tiac-dot-net]
Sent: 	Thursday, January 01, 1998 3:56 PM
To: 	tesla list
Subject: 	Gap voltages AC vs. DC

I know about the table for DC sparkgap voltage breakdown that is in the 
CRC handbook.  I decided to do a little gap experiment to see if 60Hz 
voltages had similar breakdown voltages.  My AC results turned out not to 
be anywhere near the DC test results in the CRC handbook.

I used a Powestat 116 7.5A variac, a wavetek 27XT DMM measuring voltage 
out of the variac, and a webster 10,000V 23mA transformer in brand new 
perfect condition.  My gap is made from two machine bolts, with 2.5cm 
dia. round heads, in fairly still air, gapped using feeler gauges.  I 
used a muffin fan to air out the gap between tests, and averaged the 
results of 4 measurements at each gap setting.  

Note that since I do not have a 40kV probe, I am measing voltage input to 
the OBIT and calculating ouput voltage, assuming on the OBIT to be 
linear.  I'm not sure if this is a good assumption or not.  

Gap       Variac    Volts RMS   Volts Peak	
0.030       32        2667         3771			 	
0.060       53        4416         6246			 
0.090       72  		    6042         8544			 
0.120       92  	     7667        10842			 
0.150      110        9167        12964			 
0.180      128       10667        15085	       

I am going to repeat this with sharp points later on.


Adam Smith
Epoch, Inc. Digital Music Project

www.tiac-dot-net/users/absmith/                 MP3 Demo Tracks Now Available!