Differential Transformer:

A differential transformer is a type of transducer that is used to measure linear displacement or angular rotation. It operates on the principle of electromagnetic induction and consists of a primary coil, a secondary coil, and a movable core.

1. Principle of Operation:
- The primary coil is excited by an alternating current (AC) source, which creates a magnetic field around the coil.
- The secondary coil is wound on a separate bobbin and is placed in proximity to the primary coil.
- The movable core is mechanically connected to the object whose displacement or rotation is to be measured.

2. Differential Inductance:
- When the movable core moves, it changes the magnetic coupling between the primary and secondary coils.
- This change in magnetic coupling results in a change in the mutual inductance between the coils.
- As a result, the output voltage of the secondary coil changes proportionally to the displacement or rotation of the core.

3. Variable Inductance Transducer:
- The differential transformer is a type of variable inductance transducer, as the output voltage is directly proportional to the change in mutual inductance.
- The variable inductance is caused by the movement of the core, which alters the magnetic field lines passing through the secondary coil.
- This change in inductance is converted into a corresponding change in voltage, which can be measured and used to determine the displacement or rotation.

4. Advantages:
- High accuracy: The differential transformer offers high accuracy in measuring linear displacement or angular rotation.
- Non-contact measurement: Since there is no physical contact between the core and the coils, the measurement is non-contact, which reduces wear and tear.
- Wide range of applications: The differential transformer can be used in various applications such as position sensing, level sensing, and vibration monitoring.

In conclusion, a differential transformer is a transducer that utilizes the principle of electromagnetic induction to measure linear displacement or angular rotation. It operates as a variable inductance transducer, where the change in mutual inductance between the primary and secondary coils is converted into a corresponding change in voltage. This transducer offers high accuracy, non-contact measurement, and finds applications in various fields.