Remote indication or control may be obtained
by the use of self-synchronizing motors, called synchro
equipment. Synchro equipment consists of synchro units which
electrically govern or follow
the position of a mechanical indicator or device. An
electrical synchro has two distinct advantages
over mechanical indicators: (1) greater accuracy, and (2)
simpler routing of remote indication.
There are five basic types of synchros which
are designated according to their function. The basic
types are: transmitters, differential transmitters,
receivers, differential receivers, and control transformers.
Figure T1 illustrates schematic diagrams used to show
external connections and the relative
positions of synchro windings. If the power required to
operate a device is higher than the
power available from a synchro, power amplification is
required. Servomechanism is a term which
refers to a variety of power-amplifiers.
The transmitter, or synchro generator,
consists of a rotor with a single winding and a stator with
three windings placed 120
degrees apart. When the mechanical device moves, the
mechanically attached
rotor moves. The rotor induces a voltage in each of the
stator windings based on the rotor’s
angular position. Since the rotor is attached to the
mechanical device, the induced voltage represents
the position of the attached mechanical device. The voltage
produced by each of the windings
is utilized to control the receiving synchro position.
Figure T1
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