A Selsyn, also known as a Synchro, is an electromechanical device used for transmitting angular position information between different locations. It's a type of rotary transformer that converts angular displacement into electrical signals, and vice versa. The word "Selsyn" is derived from "self-synchronized," which refers to its ability to maintain synchronization between multiple units.
How it works:
A Selsyn consists of two main components: a stator and a rotor. The stator is the stationary part, while the rotor is the rotating part. Both the stator and rotor have windings in their respective coils. The stator winding is excited by an AC voltage, which creates a rotating magnetic field.
When the rotor is turned by an external force or motion, it aligns itself with the magnetic field generated by the stator winding. This alignment causes the rotor to generate an output voltage in its winding, which represents its angular position relative to the stator. The magnitude and phase of this output voltage depend on the angle of rotation of the rotor.
Employment in control applications:
Selsyn systems were widely used in control applications before the advent of digital technology. They provided a means of transmitting angular position information over long distances without the need for complex electronic devices. Some common applications of Selsyn systems include:
Remote Indication: Selsyns were used in early aircraft and ships for remote indication of various parameters like heading, pitch, roll, and engine speed. The data from these Selsyns would be transmitted to the control station, allowing operators to monitor the status of different systems.
Antenna Positioning: In radar systems and satellite communication, Selsyns were employed to control the positioning of antennas. The Selsyns helped accurately orient the antenna towards the desired target.
Tracking Systems: Selsyns were used in tracking systems for radar antennas, telescopes, and other tracking devices. They allowed continuous feedback of the position, ensuring precise tracking of moving objects.
Industrial Control: Selsyns were used in industrial settings to control remote processes or machinery, where transmitting electrical signals over long distances was necessary.
However, with the advancements in digital communication and control technologies, Selsyn systems have become less common today. Digital encoders and other electronic sensors now provide more accurate and reliable means of measuring and transmitting angular position data. Still, Selsyns hold historical significance as they were instrumental in early control systems and automation applications.