A hygrostat is a device that switches or regulates appliances depending on humidity. According to the set humidity value, the device turns on or off the controlled output. Hygrometers (that is, hygrometers or more rarely hygrometers) are used to measure humidity. The unit of humidity is given in %RH (relative humidity).
It can be used in humidification, dehumidification or heating, fan control (extraction/inflow of air) in rooms, spaces, warehouses, archives, dryers, machines and devices, switchboards. Maintaining the right humidity for controlling e.g. botanical garden, terrarium, animal husbandry, greenhouse, solar water and air heating at home and in industry... Some hygrostats are combined with a power regulator.
Types of hygrostats
A mechanical or electromechanical hygrostat controls the switching/opening contacts by hygroscopic phenomenon. Most often, human hair is used for this purpose. The hair changes its length in proportion to the surrounding humidity.
Electronic hygrostat with digital humidity sensor
Electronic hygrostats are controlled by semiconductor sensors, their signal is amplified and processed. The electronics subsequently controls the most common relay-switching/opening contacts. Electronic hygrostats are controlled by either analog or digital sensors. We divide electronic humidity sensors into the following types:
Humidity capacitive sensor
- an electric charge is created at the output of the analog sensor, which changes according to the ambient humidity. The unit for capacitance is the farad and is denoted F.
Humidity sensor controlled by linear voltage
- there is a voltage at the output of the analog sensor, which changes according to the ambient humidity. The unit for voltage is the volt and is denoted V.
Humidity resistance sensor
- the output of the analog sensor is controlled by changing the resistance, which changes according to the ambient humidity. The unit for resistance is the ohm and is denoted Ω. - at the output of the sensor, information is transmitted in digital form, the digital flow changes according to the ambient humidity. These sensors are immune to external interference and the length of the cable connection (resistance, voltage drop or capacitance...).