ABSTRACT
The armature windings of AC electrical machines are made of coils, which create coil groups. Each phase winding has an entry and exit terminals. A single-phase winding is a system of groups of coils connected in series or in parallel. The double-layer winding is when the coil side occupies only half of the slot and the other half is occupied by another coil side. Assuming symmetrical distribution of conductors in slots around the stator core periphery the voltage induced by the magnetic rotating field in all conductors have the same amplitude and frequency. It is possible to represent the induced voltages with the aid of phasors of the same module and uniformly shifted in phase. The phasor diagram of the stator EMFs or star of slot voltages is the most precise tool for the winding design and evaluation if all coil connections are correct.
