Decagon Devices MAS-1 Посібник оператора - Сторінка 6
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MAS-1
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About the MAS-1
The MAS-1 measures the dielectric constant of the soil in order to
find its volumetric water content. Since the dielectric constant of
water is much higher than that of air or soil minerals, the dielectric
constant of the soil is a sensitive measure of water content. The
MAS-1 supplies a 70 MHz oscillating wave to the sensor prongs that
induces an electromagnetic field in the medium (soil) surrounding
the sensor. The charging and discharging of the sensor is controlled
by the dielectric of the surrounding soil.
A microprocessor on the MAS-1 measures the charging of the sensor,
and therefore the dielectric constant of the soil which is related to
the water content of the soil. The microprocessor makes a dielectric
measurement and updates the transmitted current once per second.
The transmitted 4-20 mA current can be converted to the water con-
tent of the soil using a simple calibration function.
We designed the MAS-1 to be used with standard 4-20 mA con-
trollers and monitoring systems. It cannot be used with Decagon
logging systems. For more information about using Decagon logging
systems please contact Decagon's customer support representatives.
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Specifications
Electrical
Interface: Standard 4-20 mA, 2-wire analog transmitter
Supply voltage: 12 to 32 VDC continuous
Output current: 4-20 mA
Overvoltage protection: Yes
Reverse polarity protection: Yes
Settling time: 4 seconds
Wiring:
2 ABOUT THE MAS-1
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