The specific "good" value for the Polarization Index (PI) depends on the insulation class of the equipment being tested.
Here's a breakdown of recommended minimum PI values based on heat resistance class:
| Heat Resistance Class | Recommended Minimum PI value |
|---|---|
| Class A | 1.5 or more |
| Class B | 2.0 or more |
| Class F | 2.0 or more |
| Class H | 2.0 or more |
Therefore, a PI value of 2.0 or greater is generally considered good for Class B, F, and H insulation, while 1.5 or greater is considered acceptable for Class A insulation. The PI value is an indicator of the condition of the insulation in electrical equipment. A higher PI value generally indicates better insulation quality.
