ERRORS ANALYSIS OF THE CONVERTER CAPACITY MEASURING CIRCUIT
WITH CONTACTLESS CONDUCTIVITY SENSOR

Grachev Andrey Vladimirovich, head of technical means education department, Penza State University (40 Krasnaya street, Penza, Russia), andean@mail.ru

621.317.33

Background. Conductivity sensors are widely used in devices of measuremen of conductivity and structure of liquid environments, humidity of loose and solid materials. The Contactless Conductivity Sensors (CCS) provide a number of advantages in front of more widespread contact conductivity sensors. CCS, for example, allow to carry out measurement in the wide range of temperatures of structure which are in ampoules of hostile and toxic liquid environment. Complexity of construction and the analysis of metrological characteristics of such devices consists that CCS is represented a four-element equivalent electric circuit of replacement. At the same time the considerable share of an error of measurement is introduced at a stage of transformation of passive parameters to active sizes that does actual the analysis of the active measuring system errors.
Materials and methods. The analysis of errors is carried out for CCS four-element equivalent circuit based on actual parameters used in the active measuring scheme of the differential operational amplifier by the theory of directed graphs.
Results. Compiled active measuring circuits carry information about all the parameters of the output voltage CCS operator equations. The transition from the operator equations in the form of temporary and error analysis was done using the symbol mapping in the software Maple product. Is a graph of calculated errors. Schedules of the calculated errors are submitted.
Conclusions. The carried-out analysis of errors has allowed to define requirements and to choose the OA type. From the values of error invariance were defined ranges for the measurement of valuesof non-informative parameters CCS.

contactless conductivity sensor, active measuring scheme, analysis of errors.