This chapter describes the two-axis model of a synchronous machine and the machine analysis based on Park’s model. Voltage and flux linkage relationships are established. A transformation matrix is used to translate the three-phase relations into a d–q-axis model. The steady-state equations and vector diagrams are derived from the generic relations. All the machine’s reactances are specified using a steady-state short-circuit oscillogram. For transient stability investigations, equivalent circuit and phasor diagrams are generated. A phasor diagram for a salient pole synchronous machine is created. Real and reactive power expressions are obtained. The parallel operation of synchronous generators and per unit systems are described in this chapter.