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The Optiguide's patented Wetness Sensor is an on-line monitoring sensor, which can detect free water in the air stream before it enter to the turbine compressor, in order to secure and prevent erosion damage to the compressor blades. The use of Wetness Sensor enables to work in a "Close Loop" control method. The Wetness Sensor is a capacitive sensor that comprises an internal electrode plate and isolated plate. A layer of free water that captured from the air stream forms the second electrode on the outer surface of the isolated plate, which is electronically connected to the electronic circuit. The thickness and the area of the water film is changing in accordance to the free water amount, and so does the capacitance. The capacitance is measured and converts by the controller to Wetness Index (WIDX). The wetting takes place when the inlet duct air is fully saturated (over 100% RH) or by relatively large water droplets, caused by condensation. The PLC performs fog control. It reads the wetness sensor's levels and adjusts the water flow by using of proportional valves and by turns on and off the fog stages, according to the required set point.
Power supply: 15-36 VDC
Output signal: 4 - 20 mA
Wetness level range: 100 - 300 WIDX (Wetness Index)
Temperature operating range: 0 - 60 C.
Body: Stainless steel
 
The use of Wetness Sensor for direct foggers' control (close loop control system) provides the following advantages:
The "Close loop" method combined with the "open loop" method (controlling by a psychrometric calculation, which made by the external ambient condition such as temperature and relative humidity) is much more accurate and safe than controlling with "Open loop" alone.
Prevented the possibility of damage to the compressor blades by relatively large water droplets (more than 20 microns).
Great saving in cost related to the optimal use of treated water.