1. What is Transformer Impedance?

Transformer impedance is a measure of the opposition that a transformer presents to alternating current. It is expressed as a percentage and represents the voltage drop across the transformer when full load current flows through it.

2. How Does the Calculator Work?

The calculator uses the impedance formula:

Where:

• \( Z \) — Impedance (ohms)
• \( V \) — Voltage (volts)
• \( S \) — Apparent Power (VA)

Explanation: This formula calculates the impedance of a transformer based on the square of the voltage divided by the apparent power.

3. Importance of Impedance Calculation

Details: Transformer impedance is crucial for determining voltage regulation, short-circuit current calculations, and system protection coordination in electrical power systems.

4. Using the Calculator

Tips: Enter voltage in volts and apparent power in VA. Both values must be positive numbers greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical impedance range for transformers?
A: Distribution transformers typically have impedances between 4-6%, while power transformers may range from 7-15%.

Q2: How does impedance affect transformer performance?
A: Higher impedance reduces short-circuit currents but increases voltage drop under load. Lower impedance provides better voltage regulation but higher fault currents.

Q3: Can this formula be used for all transformer types?
A: This formula provides the absolute impedance in ohms. For percentage impedance, additional calculations are needed based on base values.

Q4: Why is impedance expressed as a percentage?
A: Percentage impedance allows for easy comparison between transformers of different sizes and ratings, as it normalizes the value.

Q5: How does temperature affect impedance?
A: Transformer impedance increases with temperature due to the positive temperature coefficient of resistance in copper windings.