cable aging test (insulation resistance vs time)
cable aging test (insulation resistance vs time)
(OP)
Hi,
I'm working on a long term testing (26 weeks) on cable insulation. The readings that I've taken are capacitance, AC/DC resistance, and dissipation factor at constant 75 deg C.
As expected, the AC insulation resistance for different samples has either stayed the same or dropped after 26 weeks due to aging. What I don't get is that the DC insulation resistance readings have actually gone up quite a bit for all samples. Any logical explanations?
Thanks
I'm working on a long term testing (26 weeks) on cable insulation. The readings that I've taken are capacitance, AC/DC resistance, and dissipation factor at constant 75 deg C.
As expected, the AC insulation resistance for different samples has either stayed the same or dropped after 26 weeks due to aging. What I don't get is that the DC insulation resistance readings have actually gone up quite a bit for all samples. Any logical explanations?
Thanks






RE: cable aging test (insulation resistance vs time)
RE: cable aging test (insulation resistance vs time)
RE: cable aging test (insulation resistance vs time)
RE: cable aging test (insulation resistance vs time)
For each individual DC measurement, I charge up the megger at 500V for 15 sec and then wait 1 minute to record the reading.
I've got 4 different insulation materials and 4 samples each. 2 of the 4 insulation materials have stayed around 20 Tera ohms through out. The other two have gone up gradually each week from 20 T ohms in the beginning to over 80 T ohms around 20th week. So I'm not sure what's going on here with the DC resistance readings.
Thanks.
RE: cable aging test (insulation resistance vs time)
RE: cable aging test (insulation resistance vs time)
alwaink,
In order to comment in a meaningful way, I need to know a few parameters of your cable.
-voltage class of cable
-insulation type
-insulation thickness
Are you testing a shielded cable? If so, what is the shield type and construction? Does the cable have a jacket?
Thanks,
Benjamin Lanz
Vice Chair of IEEE 400
Sr. Application Engineer
IMCORP- Power Cable Reliability Consultants