Position Sensors by Macro Sensors
- Automotive Pressure Sensors
- Custom Pressure Sensors
- Differential Pressure - Filtration
- Digital Pressure Gauges
- Hazardous Location Pressure Transmitters
- HVAC Pressure Sensors
- Hydraulic Pressure Sensors
- Hydrogen Pressure Sensors
- Military Pressure Transmitters
- Panel Mountable Pressure Transducers
- Position Sensors - LVDT
- Railway Pressure Sensors
- Sub-Sea Pressure Sensors
- Tank Level Sensors - Submersible
- Tank Level Sensors - External
- Water Pump Pressure Sensors
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In June 2005, Macro Sensors, a division of Howard A Schaevitz Technologies, was acquired in order to complement AST/HKST’s pressure products with a full line of position sensing products. Macro Sensors manufactures LVDT and RVDT position sensors in its Pennsauken, NJ facility.
What Is An LVDT?
The letters LVDT create an acronym for Linear Variable Differential Transformer, a common type of electro-mechanical transducer that can convert the rectilinear motion of an object to which it is coupled mechanically into a corresponding electrical signal. LVDT linear position sensors that are readily available, can measure movements as small as a few millionths of an inch up to several inches, but are capable of measuring positions up to ±20 inches (±0.5 m).
The figure to the right shows the components of a typical LVDT. The transformer's internal structure consists of a primary winding centered between a pair of identically wound secondary windings, symmetrically spaced about the primary. The coils are wound on a one-piece hollow form of thermally stable glass reinforced polymer, encapsulated against moisture, wrapped in a high permeability magnetic shield, and then secured in a cylindrical stainless steel housing. This coil assembly is usually the stationary element of the position sensor.
The moving element of an LVDT is a separate tubular armature of magnetically permeable material called the core, which is free to move axially within the coil's hollow bore, and mechanically coupled to the object whose position is being measured. This bore is typically large enough to provide substantial radial clearance between the core and bore, with no physical contact between it and the coil.
In operation, the LVDT's primary winding is energized by alternating current of appropriate amplitude and frequency, known as the primary excitation. The LVDT's electrical output signal is the differential AC voltage between the two secondary windings, which varies with the axial position of the core within the LVDT coil. Usually this AC output voltage is converted by suitable electronic circuitry to high level DC voltage or current that is more convenient to use.
For more information on Macro Sensors and their position sensing capabilities, visit:
http://www.macrosensors.com