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Knee Point Voltage Calculator: An Essential Tool for Transformers

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The Knee Point Voltage Calculator is a highly useful tool that aids in calculating the knee point voltage of Current Transformers (CTs). This voltage is a critical parameter in the design and operation of transformers.

What is Knee Point Voltage?

In a Current Transformer, knee point voltage is defined as the magnitude of the secondary voltage above which the magnetizing current increases exponentially. Essentially, it's the voltage at which a CT gets magnetically saturated.

Understanding the Knee Point Voltage Formula

The Knee Point Voltage is calculated using the following formula:

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V<sub>k</sub> = √(2 * CT Ratio * Burden)


  • V<sub>k</sub> is the Knee Point Voltage.
  • CT Ratio is the Current Transformer Ratio (I<sub>1</sub>).
  • Burden is the impedance (in ohms) connected across the secondary (I<sub>2</sub>).

How to Use the Knee Point Voltage Calculator

Using our calculator is simple and straightforward. Here's a quick step-by-step guide:

  1. Input the CT Ratio (I<sub>1</sub>) into the respective field.
  2. Next, enter the Burden (I<sub>2</sub>) in the appropriate field.
  3. Click on the 'Calculate' button.

The calculator will instantly compute the Knee Point Voltage and display the result.


Let's consider a practical example:

Assume we have a Current Transformer with a CT Ratio of 100 and a burden of 5 ohms.

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Entering these values into the calculator, it computes the knee point voltage as √(2 * 100 * 5) = 100 volts.

So, the knee point voltage of the Current Transformer in this scenario is 100 volts.


Understanding the knee point voltage is fundamental to maintaining the safe operation of Current Transformers. Our Knee Point Voltage Calculator simplifies this calculation, making it a handy tool for anyone working with transformers.

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