Inductive Pressure Transducers

• As the core is pushed into the solenoid, the inductance of the coil increases in proportion to the amount of metal inside the coil. The sensitivity and linearity of the ratio inductance transducers is better than that of the variable inductance units.

Linear Variable Differential Transformer

• A linear variable differential transformer (LVDT), which can also be called a mutual-inductance element, that operates on the inductance ratio principle. Here three coils are wound onto the same insulating tube containing the high permeability iron core. Alternating current is applied to the primary coil (P) in the center, and if the core is in the center, equal voltages are induced in the secondary coils (#1 and #2)

Inductive Transmitters

• The oscillator-amplifier excites the oscillator.

• A change in process pressure results in a slight movement of the laminated core, strengthening the inductive coupling, which increases the secondary voltage to the DC amplifier.

• As the current in the feedback motor coil increases, an increased force is developed, which repositions the laminated core in the detector.

• The feedback coil applies an equal and opposite force to that produced by the change in process pressure, and, therefore, maintains the system in continuous force balance.

• The elastic sensing element deflects in proportion to the process pressure, thereby exerting a force on the balance beam through the input spring. The resulting motion changes the air gap in the detector assembly. The output current is fed through the magnet coil in the feedback motor, producing an equal and opposite force on the beam to balance the force produced by the change in process pressure.

Inductive Pressure Transducers