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Rojony Khatun Author
Rojony Khatun
CalculatorToolsProjectExpert
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Małgorzata Koperska, MD Steven Wooding
Last updated: August 15, 2025

Tap Voltage Calculator: Transformer Tap Setting Tool

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Tap voltage calculator

Calculate transformer tap voltage to match supply and load requirements. Ideal for power engineers and electricians to ensure correct voltage delivery.

electrical tap adjustment calculator

Tap voltage is computed by multiplying a transformer's nominal voltage by 1 plus or minus the tap percentage (add or subtract) in order to get tap-up voltage or tap-down voltage, respectively.

Formula & Table Summary:

  • V_nominal = Transformer nominal voltage
  • Tap% = Percentage tap adjustment
  • V_out = Adjusted output voltage

transformer voltage correction

A Tap Voltage Calculator calculated the output voltage of a transformer as a function of tap setting. Transformers use tap changers to precisely adjust the output voltage range to cope with fluctuating supply voltages or loads. Output voltage is obtained by modifying the nominal voltage on basis of a percentage change, which is determined by the tap setting. The rough formula is: rojony1.  To use as an example, a transformer with a nominal voltage of 11 kV applied at +5%, there is an output that will be: This rational tool would be useful to power engineers, electricians, and maintenance technicians within distribution systems in order to ensure stable and smooth running.

voltage adjustment tap calculator

V_nominal (V)Tap %V_out (V)
11000+511550
11000-510450

Frequently Asked Questions - Tap voltage calculator:

What is a tap voltage calculator?

It calculates the transformer output voltage based on tap settings.

Why adjust transformer taps?

To match output voltage with supply and load conditions.

What is the tap voltage formula?

Vout = Vnominal × (1 + Tap%/100).

What does +5% tap mean?

It increases output voltage by 5% over nominal.

What does -5% tap mean?

It decreases output voltage by 5% below nominal.

Can taps be changed while energized?

Only with on-load tap changers (OLTC); off-load requires shutdown.

What is an OLTC?

On-Load Tap Changer adjusts taps without interrupting power.

How accurate is tap voltage control?

Typically within ±1% to ±2% of nominal voltage.

Do taps change transformer frequency?

No, taps only change voltage level.

Can incorrect tap settings damage equipment?

Yes, prolonged incorrect voltage can overheat or underpower loads.

Rojony Khatun

Rojony Khatun

CalculatorToolsProject

Rojony Khatun is the creator of a free online tools website designed to simplify everyday and engineering-related calculations for students, professionals, and hobbyists. The platform offers a wide variety of basic and advanced calculators across key categories, including Electrical Calculators, Electronic Calculators, and Time & Date Calculators, helping users solve problems quickly and accurately.