CS650 Bodenfeuchtesensor (30cm Stäbe)
Innovativ
genauere Messungen in Böden mit hoher Leitfähigkeit
wetter  wasser  energie  gas flux and turbulence  bauwerke  boden

Überblick

Der CS650 ist eine Multiparametersonde, die innovative Technik zur Bestimmung des volumetrischen Wassergehalts, der elektrischen Leitfähigkeit und der Temperatur nutzt. Er gibt ein SDI-12 Signal aus, das fast alle unsere Logger messen können.

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Funktionen und Vorteile

  • Genauere Messungen des Bodenwassergehalts mit elektrischer Leitfähigkeit bis zu 3 dS/m ohne eine bodenspezifische Kalibrierung durchzuführen
  • Größeres Probenvolumen reduziert Fehler
  • Messwerte werden korrigiert zur Vermeidung von Effekten durch verschiedene Bodenarten und elektrische Leitfähigkeiten
  • Kalkuliert Badenwassergehalt für viele mineralische Böden
  • Vielseitiger Sensor, misst elektrische Leitfähigkeit, volumetrischen Wassergehalt, Dielektrizitätskonstante und Temperatur

Bilder

Technische Beschreibung

The CS650 consists of two 30-cm-long stainless steel rods connected to a printed circuit board. The circuit board is encapsulated in epoxy and a shielded cable is attached to the circuit board for datalogger connection.

The CS650 measures propagation time, signal attenuation, and temperature. Dielectric permittivity, volumetric water content, and bulk electrical conductivity are then derived from these raw values.

Measured signal attenuation is used to correct for the loss effect on reflection detection and thus propagation time measurement. This loss-effect correction allows accurate water content measurements in soils with bulk EC ≤3 dS m-1 without performing a soil specific calibration.

Soil bulk electrical conductivity is also calculated from the attenuation measurement. A thermistor in thermal contact with a probe rod near the epoxy surface measures temperature. Horizontal installation of the sensor provides accurate soil temperature measurement at the same depth as the water content. Temperature measurement in other orientations will be that of the region near the rod entrance into the epoxy body.

 

Spezifikationen

Measurements Made Soil electrical conductivity (EC), relative dielectric permittivity, volumetric water content (VWC), soil temperature
Required Equipment Measurement system
Soil Suitability Long rods with large sensing volume (> 6 L) are suitable for soils with low to moderate electrical conductivity.
Rods Not replaceable
Sensors Not interchangeable
Sensing Volume 7800 cm3 (~7.5 cm radius around each probe rod and 4.5 cm beyond the end of the rods)
Electromagnetic CE compliant
Meets EN61326 requirements for protection against electrostatic discharge and surge.
Operating Temperature Range -50° to +70°C
Sensor Output SDI-12; serial RS-232
Warm-up Time 3 s
Measurement Time 3 ms to measure; 600 ms to complete SDI-12 command
Power Supply Requirements 6 to 18 Vdc (Must be able to supply 45 mA @ 12 Vdc.)
Maximum Cable Length 610 m (2000 ft) combined length for up to 25 sensors connected to the same data logger control port
Rod Spacing 32 mm (1.3 in.)
Ingress Protection Rating IP68
Rod Diameter 3.2 mm (0.13 in.)
Rod Length 300 mm (11.8 in.)
Probe Head Dimensions 85 x 63 x 18 mm (3.3 x 2.5 x 0.7 in.)
Cable Weight 35 g per m (0.38 oz per ft)
Probe Weight 280 g (9.9 oz) without cable

Current Drain

Active (3 ms)
  • 45 mA typical (@ 12 Vdc)
  • 80 mA (@ 6 Vdc)
  • 35 mA (@ 18 Vdc)
Quiescent 135 µA typical (@ 12 Vdc)

Electrical Conductivity

Range for Solution EC 0 to 3 dS/m
Range for Bulk EC 0 to 3 dS/m
Accuracy ±(5% of reading + 0.05 dS/m)
Precision 0.5% of BEC

Relative Dielectric Permittivity

Range 1 to 81
Accuracy
  • ±(2% of reading + 0.6) from 1 to 40 for solution EC ≤ 3 dS/m
  • ±1.4 (from 40 to 81 for solution EC ≤1 dS/m)
Precision < 0.02

Volumetric Water Content

Range 0 to 100% (with M4 command)
Water Content Accuracy
  • ±1% (with soil-specific calibration)
  • ±3% (typical with factory VWC model) where solution EC < 3 dS/m
Precision < 0.05%

Soil Temperature

Range -50° to +70°C
Resolution 0.001°C
Accuracy
  • ±0.1°C (for typical soil temperatures [0 to 40°C] when probe body is buried in soil)
  • ±0.5°C (for full temperature range)
Precision ±0.02°C

Kompatibel mit

Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.

Datenlogger

Product Compatible Note
CR1000 (retired)
CR1000 (retired)
CR1000 (retired)
CR1000 (retired)
CR1000 (retired)
CR1000 (retired)
CR1000 (retired)
CR1000 (retired)
CR1000 (retired)
CR1000X
CR200X (retired)
CR216X (retired)
CR300
CR3000
CR350
CR5000 (retired)
CR6
CR800
CR850
CR9000X (retired)

Miscellaneous

Product Compatible Note
CR310

Additional Compatibility Information

RF Considerations

External RF Sources

External RF sources can affect the probe’s operation. Therefore, the probe should be located away from significant sources of RF such as ac power lines and motors.

Interprobe Interference

Multiple CS650 sensors can be installed within 4 inches of each other when using the standard datalogger SDI-12 “M” command. The SDI-12 “M” command allows only one probe to be enabled at a time.

Installation Tool

The CS650G makes inserting soil-water sensors easier in dense or rocky soils. This tool can be hammered into the soil with force that might damage the sensor if the CS650G were not used. It makes pilot holes into which the rods of the sensors can then be inserted.

Datalogger Considerations

Compatible Contemporary Dataloggers

CR200(X) Series CR800/CR850 CR1000 CR3000 CR9000X

Compatible Retired Dataloggers

CR500 CR510 CR10 CR10X 21X CR23X CR9000 CR5000 CR7X

FAQs für

Number of FAQs related to CS650: 54

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  1. The CS650 and the CS655 are not ideal sensors for measuring water level. However, these sensors do respond to the abrupt change in permittivity at the air/water interface. A calibration could be performed to relate the period average or permittivity reading to the distance along the sensor rods where the air/water interface is located. From that, the water level can be determined. The permittivity of water is temperature dependent, so a temperature correction would be needed to acquire accurate results.  

  2. No. The temperature sensor is located inside the sensor’s epoxy head next to one of the sensor rods. The stainless-steel rods are not thermally conductive, so the reported soil temperature reading is actually the temperature of the sensor head. If the CS650 or the CS655 is installed horizontally, which is the preferred method, then the sensor head will be at the same temperature as the soil, and the soil temperature value will be accurate. However, if the sensor is installed vertically, and/or with the sensor head above ground, the soil temperature reading will be less accurate. Because the sensor orientation is not known, no temperature correction was written into the firmware.  

  3. The CS650/CS655 manual gives a temperature correction that works in coarse sand, but it should be used cautiously with other soil types. If a temperature correction is required, it is best to determine a soil-specific temperature correction. 

    When correcting for temperature, the following effects contribute to the sensor output:

    • The effect of temperature on the measurement electronics inside the sensor head. This is a relatively small effect compared to other temperature effects.
    • The change in the dielectric permittivity of water with temperature. At 0°C, the permittivity of water is approximately 88, at 20°C it is approximately 80, and at 70°C it is approximately 64. If the sensor is in a soil at any given water content, the changing permittivity of water will cause the period average at 0°C to be higher than it is at 20°C. The same soil will have a lower period average at 70°C than at 20°C. In other words, the sensor will overestimate water content at colder temperatures and underestimate it at warmer temperatures. However, that is only true if electrical conductivity is negligible.
    • The change in water content as bound water is captured and released. In soils with high clay content, some of the water is partially or fully immobilized by electrical charges on the surface of the clay minerals. The amount of bound water is temperature dependent and may have a small effect on the sensor readings.
    • The temperature effect of bulk electrical conductivity (EC) on period average. Bulk electrical conductivity increases with temperature; as it increases, it slows down the period average.

    The interaction of these effects may be complicated. For example, with increasing temperature, two things happen at the same time:  the falling permittivity of water is decreasing the period average, and the increasing EC is increasing the period average. The net result as to whether the period average goes up or down depends on how conductive the soil is and the contributions of the other temperature effects.

  4. In soil that has a significant fraction of fines (loam, silt loam, silty clay loam, clay loam, clay), the CS655 is a suitable option because these soils tend to be more electrically conductive, and the CS655 operates over a larger range of electrical conductivity than the CS650. In applications where a smaller measurement volume is desired, such as larger greenhouse pots, the 12 cm long rods of the CS655 are preferable to the 30 cm long rods of the CS650.

  5. The CS650-series sensors have the same rugged epoxy and stainless-steel rods that have been used for water content reflectometers since the CS615-L model was introduced in 1995. There are CS615-L and CS616 sensors in many locations that have been in continuous use for more than ten years with no reported problems. If a CS650 or CS655 remains undamaged by external forces such as lightning, harsh chemicals, or animal actions, the sensor is expected to continue working for decades. 

  6. The CS650 and CS655 are warranted by Campbell Scientific to be free from defects in materials and workmanship under normal use and service for 12 months from the date of shipment. For further details, see the “Warranty” section of the CS650/CS655 manual.

  7. The volumetric water content reading is the average water content over the length of the sensor’s rods.

  8. A thermistor is encased in the epoxy head of the sensor next to one of the stainless-steel rods. This provides an accurate point measurement of temperature at the depth where that portion of the sensor head is in contact with the soil. This is why a horizontal placement is the recommended orientation of the CS650 or CS655. The temperature measurement is not averaged over the length of the sensor rods.

  9. The bulk electrical conductivity (EC) measurement is made along the sensor rods, and it is an average reading of EC over that distance at whatever depth the rods are placed.

  10. The cable properties and power requirements of the CS650 and the CS655 are such that communication with a datalogger may work for cable lengths greater than 2,000 ft. If multiple sensors are communicating through the same universal or control terminal, the total length of all of those sensors must not exceed 2,000 ft. 

    In practice, it is less expensive to purchase a new datalogger than to buy a CS650 or CS655 with 2,000 ft of cable. If the cable is run through conduit, or if a 2,000 ft long trench needs to be excavated, then the installation cost becomes more expensive than buying another data acquisition system and sensors with shorter cables.


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