Tap Voltage Calculator



A tap changer is a device in a transformer that allows for adjustments to the turns ratio, thereby changing the transformer’s output voltage. This adjustment ensures that the output voltage remains within specified limits even if the input voltage fluctuates. The tap voltage is the voltage at which the transformer is operating based on the selected tap position.


The formula for calculating tap voltage is straightforward:

Tap Voltage (Vt) = Turns Ratio (N) x Primary Voltage (Vp)


  • Tap Voltage (Vt) is the voltage at the selected tap position.
  • Turns Ratio (N) is the ratio of the number of turns on the secondary coil to the number of turns on the primary coil.
  • Primary Voltage (Vp) is the voltage supplied to the primary coil of the transformer.

How to Use?

Using the Tap Voltage Calculator is simple. You need to know the turns ratio and the primary voltage. Enter these values into the calculator, and it will provide you with the tap voltage. This information is vital for ensuring that the transformer operates within the desired voltage range.


Let’s consider an example:

Suppose you have a transformer with a turns ratio (N) of 5:1, and it is supplied with a primary voltage (Vp) of 240 volts. To find the tap voltage (Vt), use the formula:

Vt = N x Vp Vt = 5 x 240 Vt = 1200 volts

In this case, the tap voltage is 1200 volts.


Q1: Why is tap voltage important? A1: Tap voltage is crucial because it allows transformers to operate effectively and maintain a stable output voltage, even when the input voltage fluctuates.

Q2: Can tap voltage be adjusted manually? A2: Yes, some transformers have manual tap changers that allow operators to adjust the tap voltage to suit specific operating conditions.

Q3: What happens if the tap voltage is not set correctly? A3: Incorrect tap voltage settings can lead to inefficient operation, voltage instability, and potential damage to connected equipment.


The Tap Voltage Calculator simplifies the process of determining tap voltage in transformers. By understanding and calculating the tap voltage, engineers and electricians can ensure that transformers operate efficiently and within specified voltage ranges. This tool is invaluable for maintaining the reliability and stability of electrical systems.

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