In conventional power plants, the exhaust gas is usually cleaned by Flue G as desulfurization. The remnant of this approach is FGD_Gypsum, which is mostly drained on the Vakuum band filter. RGI sensors can determine residual moisture online. Based on the immediately available results, the dryer can compensate the process accordingly and can improve the quality of the gypsum. The sled with integrated humidity sensor slides over FGD_Gypsum's Vakuum belt filter. To optimize the measurement results, the wiper blade smoothes the plaster surface