Correct Answer - Option 4 : Limited dynamic response
LVDT (Linear Variable Differential Transformer) is the most widely used inductive transducer that converts the linear motion into the electrical signal. A linear variable differential transformer (LVDT) has one primary winding and two similar secondary windings in series opposition (differential mode) but not a toroidal magnetic core.
It is connected in differential mode to obtain:
- an output voltage that is phase-sensitive i.e. the output voltage has a phase that can lead us to a conclusion whether the displacement of the core took place from right to left or from left to right
-
to establish the null or the reference point for the displacement of the core
Advantages of LVDT:
- High range
- Linearity
- Friction and electrical isolation
- Immunity from external effects
- High output and high sensitivity
- Ruggedness
- Low hysteresis
- Low power consumption
Disadvantages of LVDT:
- Relatively large displacements are required for appreciable differential output
- They are sensitive to stray magnetic fields, but shielding is possible; This is done by providing shields with longitudinal slots
- Many a times, the transducer performance is affected by vibrations
- The receiving instrument must be selected to operate on AC signals, or a demodulator network must be used if a dc output is required
-
The dynamic response is limited mechanically by the mass of the core and electrically by the frequency of applied voltage
- Temperature affects the performance of the transducer; But when temperature effects are expected to influence the performance, manganin wire may be used instead of copper wire
