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