What is the term for selectors with two electrically connected motors?

The term for selectors with two electrically connected motors is "Selsyn selector." This type of selector operates using a system of synchronous motors, allowing for accurate position control and feedback. The Selsyn system is particularly effective in applications requiring precise synchronization between remote units, as each motor transmits its position information to the other. This arrangement facilitates a reliable and efficient means of controlling multiple connected devices simultaneously.

In contrast, the other options describe different systems or configurations. A mechanical selector operates using physical mechanical components rather than electrical motors. A relay selector relies on electromagnetic relays for switching functions, which do not provide the same level of synchronization as a Selsyn setup. Lastly, a single motor selector refers to systems with just one motor; therefore, it does not involve multiple interconnected motors in operation. The unique functionality and design of the Selsyn selector make it ideal for situations that require precise and coordinated control over multiple motors.