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Abstract

The invention relates to a method for monitoring the function of a capacitive pressure measuring cell (10) comprising a measuring capacitor (C_M) and a reference capacitor (C_R) as well as a temperature element, wherein in an evaluation unit the pressure measurement value p is obtained by forming the quotient Q from the capacitance values of the reference capacitor (C_R) and the measuring capacitor (C_M). The method is characterized by the following method steps:

in a matching procedure the characteristic curve of the quotient Q and the capacitance values of the measuring capacitor (CM) are each stored in a lookup table versus the pressure and at different temperature scenarios;then the corresponding absolute value of the quotient Q and of the capacitance value of the measuring capacitor (CM) from the lookup table are continuously assigned respectively to the determined pressure measurement value p at the temperature detected at this moment by the temperature element;the behavior of the course of the two absolute values of the quotient Q as well as of the capacitance value of the measuring capacitor (CM) is compared with each other;in the case of a significant deviation from an expected behavior, the evaluation unit is temporarily switched into a safety mode and meanwhile the gradient of the temperature element is detected and evaluated;in the case of a significant increase of the gradient of the temperature element, a temperature compensation is initiated; orin the case of an unchanged gradient of the temperature element, an error signal is generated.

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