DC spark gap vs. voltage

[Spazmodica]

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

[YT2095]

2 things, can`t you write back to the original electrons manufacturer and request more data (if not That specific data that you need).

 

and shouldn`t this callibration be taken under max compression rather than at 101kpa?

 

I can`t really help with your problem in the main, only present ideas that May help. I fall off the map past spark plugs and magnetos

[BhavinB]

how about using Paschen's Curve?

http://www.duniway.com/images/pdf/pg/Paschen-Curve.pdf

[swansont]

http://home.earthlink.net/~jimlux/hv/paschen.htm

is another source, giving Paschen's law with the dependence on gap distance

[Spazmodica]

Honeywell is our OEM and talking to them is like you trying to call the engineer who designed your transmission asking about clutch plate materials. Definitely David & Goliath.

 

Thanks for the info. Many more parts to the problem than I thought. I'll be making sparks next week!

[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