| | Jan 7, 2014 — Since the 1950s, power generation remains one of the largest market segments serviced by LVDT linear position sensors. As simple devices with only a few coils of wire and a ferrous core, LVDTs can withstand high levels of shock and vibration, get extremely dirty and still operate according to their specifications.
The ability to separate LVDT electronics, which are located in the turbine control system from the LVDT coils, is one of the main reasons that these sensors can survive so well in power plants. With electronics remotely located, an LVDT can withstand high temperatures of 350 to 400°F on the turbine while sensors with built-in electronics would have to be specially configured at a much higher price to offer electrical components that can withstand this level of heat.
As gaseous vapors are present in gas turbines, LVDTs installed on turbines must meet intrinsically safe parameters and be approved by certified agencies such as UL, FM, CSA and ATEX. As LVDT coil designers must these requirements into consideration when establishing a design, a standard has been set based on the environment called an “ignition curve”. Designed with an inductance below the ignition curve, the LVDT linear position sensor in standard operation or in a fault condition never has enough power to ignite any gaseous vapors present.
While other technologies have been investigated to serve as feedback devices, the power generation industry has standardized on LVDT technology. Lasers become blind due to dirt and grime, capacitive and eddy current sensors don’t have the capability to measure long strokes. Potentiometers, magnetostrictive and string-pots (draw wire sensors) have difficulty with the temperature, vibration and intrinsic safety requirements.
For a copy of Macro Sensors brochure on LVDT Position Sensors for Energy and Power Generation Applications, download: http://www.macrosensors.com/downloads/brochures/energy_brochure_060612_web.pdf
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