The relative humidity transmitters, also available combined with temperature sensor, are used in air conditioning system for the measurement of relative humidity. They measure the relative humidity value to be measured by a capacitive sensitive element whose signal, suitably linearized and amplified, is transformed into a voltage signal (0..10 V) or current (4..20 mA ) at the terminals of output.
in models with temperature sensor the sensing element is constituted by a resistance Balco, NTC (10 kΩ) or PTC (1 kΩ).