Operation; Measurement; Low Power Operation; Long Cable Lengths - Campbell EE181 Product Manual

FIGURE 7-2. EE181 and RAD10E solar radiation shield on a tripod mast

8. Operation

8.1 Measurement

The probe uses E+E Elektronik coated HC101 capacitive sensor to measure RH and a 1000 Ω PRT
to measure temperature. Campbell Scientific data loggers measure the analog voltage outputs of
VoltSE()
the EE181 Temperature and Relative Humidity Probe with the measurement
instruction.

8.2 Low power operation

The EE181 draws less than 1.2 mA powered from 12 V. The EE181 can be continuously powered
from the 12V terminal, or power can be switched with the SW12V terminal to conserve battery life.
When power is switched, a two-second warm-up period is required. This is programmed with the
Delay()
instruction, using 0 for the delay option.

8.3 Long cable lengths

Long cable lengths cause errors in the measured temperature and relative humidity. The
approximate error in temperature and relative humidity is 0.31 °C and 0.31% per 100 feet of cable
length, respectively.
EE181 Temperature and Relative Humidity Probe 12