In a motor such electric fan it needs magnetic field to operate if a coil is being energized it creates magnetism. How many speed does your electric fan has? usually it has 3 speeds so it need 3...
If it is a step down transformer, the windings with the thin wire is the primary and the thicker wire will be the secondary
However, if the wires is not visible, then use an ohmmeter (or...
Transformers may have mulitple windings, but must have at least two. The Primary is the higher voltage, often denoted H. The secondary is the lower voltage (higher amperage) winding, often denoted X....