Hermetically-Sealed LVDT Sensors Feature 4-20 mA I/O In Both 2-Wire or 3-Wire Configurations For Simplified Field Integration

Jan. 6, 2007
Macro Sensors, (www.macrosensors.com), specialists in the manufacture of LVDT-based linear position sensors and gaging probes, offers a new family of rugged, hermetically sealed LVDTs that provide 4-20 mA input/output for easy field integration with PLCs, digital indicators, host computer-based data processing, and QC data collection systems. Units can be configured for either loop powered two-wire or externally powered three-wire sourcing output to address different I/O requirements in various applications. Offered in both hard-connected and spring-loaded versions, Macro Sensors’ 4-20 mA current loop output LVDTs are hermetically sealed against dirt, water, steam, solvents, and other corrosive elements, that enables their installation in hostile environments while the loop wiring connects to remote indicators and/or controllers located in environments safe from hostile conditions. These units offer precise output with a maximum linearity error of only "0.1% of full range output using a statistically best-fit straight line. For mechanical position measurement where a hard connection can be made to the test piece, Macro Sensors offers the HSI 750 and HSIR 750 Series of free-core LVDTs that provide a 4-20mA current loop output. Available in full ranges from 0.10 inches (2.5 mm) to 20 inches (500 mm), these _-inch (19mm) diameter LVDTs are available as either blind bore units (HSI 750 Series) terminated in a glass-sealed axial connector that prevents the core from passing completely through the coil assembly or in a through-bore design (HSIR 750 Series) with the connector mounted radially to facilitate easy access to either end of the LVDT’s core for better mechanical support and core guidance, as well as easier cleanout in dusty or gritty environments. The radial connector also allows a shorter installed length to the sensor compared to units of the same range with axial connectors. For applications where a hard mechanical connection cannot be made between the sensor’s moving core and the test piece, Macro Sensors offers the GHSI 750 and GHSIR 750 Series of spring-loaded LVDTs. This style of sensor consists of a spring-loaded shaft connected to the core of the LVDT that runs in a precision sleeve bearing. The probe shaft is extended by a spring exerting a nominal force of 6 to 20 ounces depending upon total range. These sensors feature a measurement repeatability of 0.0001 inches (2.5 :m) or better. Available in full ranges of 0.10 inches (2.5 mm) to 4 inches (100 mm), the GHSI 750 and GHSIR 750 Series are ideal for the use in machine tool controls, go/no-go inspection, and statistical quality control (SQC) systems or as part of a closed-loop control system. For simplified mounting, both series have a 1/2-20 UNF-2A threaded front end of the housing, permitting the user to install the LVDT in a mating threaded part or by using the two hex nuts furnished with the sensor. This results in a ready-to-use package for position measurements and long range gaging applications. Units are also available with a radial connector version(GHSIR) that allows a shorter installed length, and in air-extend/spring-retract versions for custom gaging systems used with transfer lines and automated test stands.