Transformer Impedance Calculator

A transformer's winding ratio determines how impedance shifts between its primary and secondary sides — a critical factor in audio, RF, and power circuit design. Enter your Primary Turns (Np), Secondary Turns (Ns), and either the Primary or Secondary Impedance into the Transformer Impedance Calculator, then select your Calculation Type to get the Referred Impedance on the opposite side. Secondary outputs include the Turn Ratio, Impedance Transformation Ratio, and inverse turn ratio.

Number of turns in primary winding

Number of turns in secondary winding

Ω

Impedance value on primary side

Ω

Impedance value on secondary side

Results

Referred Impedance

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Turn Ratio (Np:Ns)

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Impedance Transformation Ratio

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Turn Ratio (Ns:Np)

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Frequently Asked Questions

What is Transformer Impedance?

Transformer impedance is the opposition to current flow in a transformer circuit, consisting of resistance and reactance components. It affects voltage regulation, short-circuit current, and power transfer efficiency.

Why is Transformer Impedance important?

Transformer impedance is crucial for determining voltage regulation, fault current levels, parallel operation capability, and overall system stability. It directly impacts transformer performance and protection system design.

How does Impedance affect Transformer Performance?

Higher impedance reduces short-circuit current but increases voltage regulation. Lower impedance improves voltage regulation but increases fault current. The optimal impedance depends on specific application requirements.

What is the Z impedance of a transformer?

Z impedance (percentage impedance) is the impedance of a transformer expressed as a percentage of its rated impedance. It's typically measured during short-circuit tests and ranges from 4% to 10% for power transformers.

How do you calculate referred impedance?

Referred impedance is calculated using the turn ratio squared. When referring from secondary to primary: Z_referred = Z_secondary × (Np/Ns)². When referring from primary to secondary: Z_referred = Z_primary × (Ns/Np)².

What is the relationship between turn ratio and impedance ratio?

The impedance transformation ratio is the square of the turn ratio. If the turn ratio is N, then the impedance ratio is N². This relationship is fundamental in transformer impedance calculations.

Can transformer impedance be measured?

Yes, transformer impedance is measured through short-circuit tests where one winding is short-circuited and reduced voltage is applied to the other winding until rated current flows. The impedance is calculated from the applied voltage and current.