PI/DAR is one of the criteria used to judge whether insulation is good (PASS) or bad (FAIL). The display is automatically calculated from the insulation resistance value after two specified times after the test voltage is applied, and if the PI or DAR is close to 1, it is judged that the insulation of the object under test has deteriorated.. The dielectric absorption ratio is the ratio of two time-resistance readings such as a 60-second reading divided by a 30-second reading. If the ratio is a 10-minute reading divided by a 1-minute reading, the value is called the polarization index. The principle behind the test is that the resistance would increase with time as the capacitive and polarizing currents begin to subside.
The polarization index test is a 10-minute to 1-minute ratio test of insulation resistance.Similarly, the DAR test is a 60-second to 30-second insulation resistance ratio test. The advantage of the insulation resistance time ratio test is the cancellation of measurement errors caused by temperature.. The Dielectric Absorption Ratio (DAR) test checks how quickly this absorption current drops off over time by measuring the insulation resistance at two specific moments: after 30 seconds and after 60 seconds. If the insulation is in good condition, the resistance reading after 60 seconds (R60) should be higher than after 30 seconds (R30).