What is insulation resistance testing?
- Basically, you're applying a voltage (specifically a highly regulated, stabilized DC voltage) across a dielectric, measuring the amount of current flowing through that dielectric, and then calculating (using Ohm's Law) a resistance measurement.
- Let's clarify our use of the term "current." We're talking about leakage current. The resistance measurement is in megohms. You use this resistance measurement to evaluate insulation integrity.
What affects insulation resistance readings?
- Insulation resistance is temperature-sensitive. When temperature increases, insulation resistance decreases, and vice versa.
- A common rule of thumb is insulation resistance changes by a factor of two for each 10 DegrC change. So, to compare new readings with previous ones, you'll have to correct your readings to some base temperature.
- For example, suppose you measured 100 megohms with an insulation temperature of 30 DegrC. A corrected measurement at 20 DegrC would be 200 megohms (100 megohms times two).
No comments:
Post a Comment