What are the types of Trans Tek LVDTs

What are the types of Trans Tek LVDTs

LVDT is a universal but relatively simple device used in various applications and industries to measure displacement. Therefore, there are different types of LVDTs to choose from to accommodate their seemingly endless uses. This may be a lengthy discussion as we can categorize LVDTs separately by operation, configuration, and application. To shorten the duration of attention, we will quickly process operations, followed by configuration and application.

AC and DC LVDT

AC LVDT uses alternating current (AC) voltage to excite the primary coil, which generates a voltage difference proportional to the displacement of the iron core in the secondary coil. They are known for their high precision and sensitivity. DC LVDT is an AC LVDT with added oscillator/demodulator circuit, allowing it to operate under DC voltage input. They may be more expensive and have lower frequency response, but DC analog outputs are usually easier to connect.

Basic/Rod LVDT

The basic type of LVDT is a free floating core unit, commonly referred to as a rod type LVDT. It consists of a shell and a core, with an extension rod connecting the core and the tested moving part. The iron core is neither connected to the primary coil nor to the secondary coil, and its position between the coils determines the output voltage of the transformer. Rod LVDT has high precision, can provide a wide range of motion, and can withstand impact and vibration.

Spring loaded LVDT

A spring-loaded LVDT, commonly referred to as a measuring LVDT, consists of an internal spring mechanism that applies a constant force to the iron core. In this case, the extension rod is more like a spring-loaded plunger used to capture rock cores. The spring-loaded LVDT provides consistent contact, enabling highly reproducible measurements. In addition, due to the reduced friction between the core and the shell by the springs, they have excellent sensitivity and accuracy. They are compact because the springs can absorb shocks and vibrations. One drawback is that the spring slows down the frequency response of LVDT.

What are the types of Trans Tek LVDTs

These characteristics and coupling make spring loaded LVDTs very suitable for various measurement applications. Using single point measurement, the Jian end directly contacts the object at a single point, which is an ideal choice for measuring thickness, diameter, or runout. Through multi-point measurement, multiple edges are arranged in a specific configuration, allowing for simultaneous measurement of complex shapes or contours. Spring loaded LVDT can also be used for force limiting measurements, where the spring preload can be adjusted to limit the force applied at the jian end and protect fine surfaces from damage.

Trapped LVDT

Unlike the pole type, the pole type core can move freely, while here, the core is contained within the shell and will not come out. The shell sleeve can slide back and forth along the axis of the transformer, but the iron core itself is still fixed in it. On the positive side, they are compact in structure, relatively stable, and provide frictionless operation. However, if the rod or core breaks, it cannot be replaced. Therefore, they may not be as popular as other configurations, but they do have their own place in certain applications.