The impedance voltage of a transformer is a crucial parameter that plays a significant role in understanding its performance and impact on the overall power system. When the secondary winding of a transformer is short-circuited, the voltage applied by the primary winding to allow the rated current to flow is termed the impedance voltage.

Symbolized by Uk, the impedance voltage is often expressed as a percentage of the nominal voltage of the system. This expression is given by the formula: Uk% = (Uk/Uh) × 100%, where Uk is the impedance voltage and Uh is the nominal voltage of the system.

The percentage representation is a convenient way to compare the magnitude of the impedance voltage relative to the overall system voltage. This parameter is crucial for several reasons:

Transformer Cost and Performance: The impedance voltage is directly related to the design and characteristics of the transformer. Transformers with lower impedance voltages generally have higher short-circuit currents, affecting their construction and cost. The choice of impedance voltage is a trade-off between transformer cost and performance, and it influences the overall efficiency and reliability of the transformer.

System Stability: The impedance voltage is a key factor in determining the stability of the power system. Higher impedance voltages contribute to higher short-circuit currents, affecting the system's ability to withstand and recover from faults. Careful consideration of the impedance voltage is necessary to maintain stability and prevent cascading failures in the power grid.

Power Supply Quality: The impedance voltage influences the quality of the power supply. Excessive impedance can lead to voltage drops during high-demand periods or fault conditions, affecting the performance of connected devices and machinery. Properly selecting and managing impedance voltage is essential to ensure a stable and reliable power supply.

The impedance voltage of a transformer is a critical parameter that demands careful consideration during the design and operation of power systems. Balancing cost, performance, system stability, and power supply quality, engineers strive to optimize the impedance voltage to meet the specific requirements of the application. As technology advances, transformer designs continue to evolve, and the understanding of impedance voltage remains integral to the efficient and reliable functioning of power systems.