physicsstuff

I perform functional tests on turbine auxiliary power units (APUs) and accessories. I am acquiring equipment for specific tests and I have an adjustable spark gap with ball tips that I want to use for testing ignition exciters. My problem is that the OEM specifies voltage setting points of their spark gap and I do not have any scale on mine, just a distance that I can measure.

 

The exciters I test are rated at 18kV. The test specifies 15kV and 24kV points. I may need to go higher and/or lower with units I will be testing from other engine models.

 

Does anyone have a table or reference formula for setting a spark gap for a specific DC voltage in air? I know that there must be adjustments for humidity, but I have calibrated humidity meters and a barometer if needed.

 

-Dan The Man

You can find spark distances P E-55 61st edition of Handbook of Physics & Chemistry. Partial list below:

PKv needle points(in) 5cm spheres

5 0.42 .15

10 0.85 .29

20 1.75 .60

40 3.81 1.30

80 11.1 3.26

100 15.5 4.77

200 35.7

300 54.7

Maybe find data in Radio Amateurs Handbook (any old addition) Have fun...

physicsstuff