Impedance is a fundamental concept in the field of electrical engineering, especially when dealing with transformers. It refers to the measure of opposition that a circuit presents to the flow of alternating current (AC) and is a combination of resistance and reactance.

Components of Impedance:

1. Resistance (R): This is the opposition to current flow due to the conductors and components in the circuit. It remains constant regardless of the frequency of the AC.
2. Reactance (X): This is the opposition to current flow due to inductance and capacitance in the circuit. Unlike resistance, reactance varies with the frequency of the AC.

Impedance (Z) is calculated using the formula: = Z= sqrt{R^2 + X^2}  

Role of Impedance in Transformers:

1. Voltage Regulation: Impedance plays a crucial role in determining the voltage regulation of a transformer. It affects how the output voltage changes with varying load conditions. A transformer with low impedance will have better voltage regulation.
2. Short-Circuit Current: The impedance of a transformer determines the magnitude of the short-circuit current. Lower impedance results in higher short-circuit current, which must be considered when designing protection systems.
3. Power Transfer Efficiency: Impedance affects the efficiency of power transfer between the primary and secondary windings of a transformer. Optimal impedance matching ensures maximum power transfer and minimal losses.

Measuring Impedance:

Impedance can be measured using specialized equipment such as an impedance analyzer or an LCR meter. In transformers, it is often represented as a percentage, indicating the voltage drop in the transformer due to its impedance under full-load conditions.

Practical Implications:

Understanding impedance is essential for the proper selection and operation of transformers in an electrical system. It ensures efficient power delivery, safe operation, and compatibility with other components in the system.