Process for automatically monitoring output signal from moisture humidity measurement device to avoid taking sensor off-line for calibration

摘要

The output signal from a humidity sensor is automatically monitored to avoid taking the sensor off-line for calibration. In a process for automatically monitoring the output signal from a moisture /humidity measurement device, a first measurement is made and the value (M) is permanently recorded before interrupting the voltage applied to the device. The time (t1) required to re-establish the value (M) is recorded. The procedure is repeated as required to make measurements, each time recording the time (t1) and the subsequent time (t2) required to re-establish the first value (M). A threshold value , s = t2 - t1 is calculated and compared with a set-point value, s'; when s' is reached or exceeded, a signal is generated, or an alarm initiated.