1, draw a computational circuit diagram. The rated parameters of each component considered in the short-circuit calculation are represented and the components are numbered in turn. (2) To determine the short circuit calculation point. The selection of short-circuit calculation points allows the electrical component stoop to pass through the electrical component stoop to the maximum possible. 3, according to the selected short-circuit calculation point to draw the equivalent circuit diagram, and calculate the main components of the circuit impedance. 4, the equivalent circuit is simplified, the equivalent total impedance is derived, the calculation of short-circuit current and short-circuit capacity.