CORE INTUITION
The transformer is the first brake on the fault.
Its impedance limits current. At 5.0%, a terminal fault can reach about 20.0 times rated current.
Lower uk%→Less limitation→Higher fault
Electrical Engineering · CHAPTER 04 · FOCUSED LESSON
Fault current laboratory
Change transformer ratings and watch prospective short-circuit current react.
LIVE SIMULATION · TRANSFORMERS
Prospective fault current
GRID15 kV
T1 · Dyn5
FAULT27.8 kA
Rated current1.4 kA
Prospective fault current27.8 kA
Breaker capacity≥ 36 kA
Simplified three-phase estimate · Infinite primary source assumption