| 摘要 |
FIELD: instrumentation.SUBSTANCE: contact with a sample is made by means of two electrodes located along the line, perpendicular to fibres of the sample at the fixed distance from each other. The voltage is applied to the measuring cell, the time of comparison of the current amplitude with the threshold value is registered and humidity is determined. The humidity is determined by the frequency of calibration characteristics the duration of which in each cycle is determined by the measurement interval the front of which is formed at the time of comparison of threshold voltage with the line voltage of dynamic characteristics of the measured cell consisting of series connected wet material and reference capacity. Then the cut is organized by change of polarity of threshold voltage. The calibration characteristics are the function of rated humidity and the function of limit frequency of dry material impulses which are determined during measurement of the limit frequencies corresponding to the lower and top boundaries of measured range and by which the rated measures are determined: limit frequency and rated humidity. The device for determination of humidity of capillary and porous materials by dynamic characteristics consists of the measuring cell which comprises the series connected studied material and the reference capacity. The multivibrator is arranged by connecting of the measuring cell to a negative feedback of the operational amplifier, to the positive feedback of which the reference voltage divider based on resistors is connected, and the output indicator is a frequency meter.EFFECT: improvement of metrological efficiency, namely the accuracy of measurements, due to exclusion of nonlinearity.3 cl, 5 dwg |
