Campbell HFP01SC Uživatelský manuál stáhnout pdf (Strana 5)

Model HFP01SC

Self-Calibrating Soil Heat Flux Plate

1. General Description

The HFP01SC Soil Heat Flux plate consists of a thermopile and a film heater.

The thermopile measures temperature gradients across the plate. During the

in-situ field calibration, the film heater is used to generate a heat flux through

the plate. The amount of power used to generate the calibration heat flux is

measured by the datalogger. Each plate is individually calibrated, at the

factory, to output flux.

In order to measure soil heat flux at the surface, several HFP01SCs are used to

measure the soil heat flux at a depth of eight centimeters. A TCAV Averaging

Soil Thermocouple is used to measure the temporal change in temperature of

the soil layer above the HFP01SC. Finally, a CS616 Water Content

Reflectometer is used to measure the soil water content. The temporal change

in soil temperature and soil water content are used to compute the soil storage

term.

The -L option on the model HFP01SC Soil Heat Flux plate (HFP01SC-L)

indicates that the cable length is user specified. The HFP01SC-L has two

cables; the first cable is the signal output cable and the second is the heater

input cable. Two analog inputs are required to measure the HFP01SC-L This

manual refers to the sensor as the HFP01SC.

2. Specifications

Operating Temperature: -30°C to +70°C

Storage Temperature: -30°C to +70°C

Plate Thickness: 5 mm (0.2 in.)

Plate Diameter: 80 mm (3.15 in.)

Power Consumption

During Self Calibration: 1.3 W (108 mA @ 12 vdc)

Sensor: thermopile and film heater

Measurement Range: ±100 W m

-2

Signal Range (nominal): ±5 mV for the above range (sensor), 0 to 2 V

(while the film heater is powered)

Accuracy: ±3% of reading

Sensitivity (nominal): 67 µV W

-1

-2

Sensor Resistance (nominal): 2 Ω

Heater Resistance (nominal): 100 Ω

Current Sensing Resistor: 10Ω 1% 0.25 W

Thermal Conductivity: 0.8 W m

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Campbell HFP01SC Uživatelský manuál Strana 5