Why does Transformer Impedance important so much during a Fault?
A transformer may be rated for hundreds of MVA, but its short-circuit impedance plays a critical role in determining the fault current.
During a short circuit, the current is influenced not only by the source impedance but also by the transformer’s impedance between the supply and the fault location.
Higher transformer impedance generally limits the prospective fault current, while lower impedance allows higher fault currents to flow. Understanding transformer impedance is essential for accurate short-circuit calculations, circuit breaker selection, relay coordination, and protection system design.