Polarity Index Calculator

Formula

The formula to calculate the Polarity Index (PI) is:

\[ PI = \frac{R10}{R1} \]

Where:

\( PI \) is the Polarity Index
\( R10 \) is the insulation resistance after 10 minutes (ohms)
\( R1 \) is the insulation resistance after 1 minute (ohms)

Definition

Polarity Index (PI): A measure of the condition of electrical insulation, calculated as the ratio of the insulation resistance after 10 minutes to the resistance after 1 minute.
Insulation Resistance after 10 Minutes (R10): The resistance measured after 10 minutes of applying a test voltage, in ohms.
Insulation Resistance after 1 Minute (R1): The resistance measured after 1 minute of applying a test voltage, in ohms.
Significance: The polarity index helps in assessing the quality and aging of electrical insulation. A higher PI indicates better insulation quality.

Example

Let's say the insulation resistance after 10 minutes (R10) is 5000 ohms and the insulation resistance after 1 minute (R1) is 1000 ohms. Using the formula:

\[ PI = \frac{5000}{1000} = 5 \]

So, the polarity index is 5.