Figure 1-4.Typical synchro assembly.
In this section we will discuss how rotors and stators are constructed and how the synchro is
assembled. Each synchro contains a rotor, similar in appearance to the armature in a motor, and a stator,
which corresponds to the field in a motor. The synchro stator is composed of three Y-connected windings
(S1, S2, and S3). The rotor is composed of one single winding (R1 and R2). As you can see in the figure,
the rotor winding is free to turn inside the stator. The rotor is usually the primary winding and receives its
voltage (excitation) from an external voltage source. The stator receives its voltage from the rotor by
There are two common types of synchro rotors in use-the SALIENT-POLE ROTOR and the DRUM
or WOUND ROTOR. The salient-pole rotor shown in figure 1-5 has a single coil wound on a laminated
core. The core is shaped like a "dumb-bell" or the letter "H."
Figure 1-5.Salient-pole rotor.