IR testing in wet/humid conditions

[davo72]

Hi all,

I'm in the process of writing some procedures/guidelines in relation to insulation resistance (IR) testing.

I have a situation where we have some "unwritten" rules in relation to reducing insulation resistance when testing is performed in wet/humid weather. Some of our more experienced cable testers sometimes reduce the IR level to 75% of the level stipulated in our procedures. Obviously the cable withstands the 1kV (or 5kV) AC voltage and after putting the cable in service in the past, it has performed reliably for many years (I have been told). This generally happens with some LV aged cables being put back into service after repairs.

I have researched many different standards and cannot find any mention of this sort of practice in these documents (ie. reducing IR level in wet/humid weather).

If there's anyone out there that has faced a similar problem in the past, I'd like to know about it. Also, if anyone knows of any standard that refers to IR levels in wet/humid weather, I'd like to hear about that as well.

I am a little inexperienced in this area. Thanks to anyone who can assist in any way.

 

[Zogzog]

There is no correction factor for humidity like there is for temp. We try to test at the same time every year so humidity levels are about the same, and we record humidity for every IR test.