AC-Operated LVDT Position Sensors
for Hazardous Locations
ATEX Approved

Macro Sensors’ HLR 750 Series of 3/4 inch diameter high reliability LVDT position sensors are specifically designed for use in gas turbine environments. These hermetically sealed AC-LVDTs are listed for [Class 1, Division 1, Groups A, B, C, D and Class 1, Zone 2, Group IIC Hazardous Locations] -or- [Class 1, Division 2, Groups A, B, C, D and Class 1, Zone 2, Group IIC Hazardous Locations] by Underwriters Laboratories. Although these ratings share a common LVDT, each set of approvals retains specific operating requirements [Ambient Temperature: -20°F to 212°F (100°C), Maximum Input: 6 V rms @ 2.5 kHz, and ONLY WHEN INSTALLED PER MACROSENSORS 011600000113 Standards] -or- [Ambient Temperature: -20°F to 300°F (150°C)], respectively. Constructed entirely of stainless steel for environmental robustness, they feature a through-bore design which makes the LVDTs’ cores accessible from both ends for better mechanical support and core guidance and facilitates cleanout in dusty or dirty locations. An HLR LVDT’s lead wires exit through a radially mounted 1/2-14 NPT male threaded conduit fitting for easy attachment to an explosion-proof junction box as well as rigid or flexible conduit.

Available in measuring ranges from ±1 inch to ±10 inches, HLR 750 Series position sensors feature the high resolution, excellent repeatability, and low hysteresis (typically better than 0.01% of full scale output for each) that is associated with time-proven LVDT technology. The maximum linearity error of these sensors is ±0.25% of full range output, using a best-fit straight line derived by the least squares method. A particularly desirable feature of HLR 750 Series LVDTs is that the sum of their secondary voltages is essentially constant and independent of core position, so they can be used equally well with either conventional differential input LVDT signal conditioners or with ratiometric signal conditioning circuits.

HLR 750 Series LVDTs offer reliable contactless position measurement for critical applications in power plants using gas turbines such as fuel valve position feedback, vane pitch servo controls, governor controls, and generator shell expansion measurement. Their temperature rating permits these LVDTs to serve in many applications in steam turbine power plants as well. They also are ideal for throttle position sensing on engine-driven compressors in natural gas pumping stations, height measurement for head boxes and slicers in paper mills, edge detectors and web tension controls in plastic film plants, and real time position sensing for all types of valves in chemical process plants.