Patent ID: 11920972
Assignee: ENDRESS+HAUSER SE+CO. KG
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 6:
7. A method for state monitoring of a coil that is a part of a device for determining at least one process variable of a medium in a containment, the method comprising:
supplying the coil with an alternating electrical excitation signal and varying a frequency of the excitation signal from a starting frequency to an ending frequency;
receiving an electrical received signal from the coil during the varying of the frequency of the excitation signal;
measuring a phase shift between the excitation signal and the received signal;
ascertaining a first frequency for the excitation signal such that a phase shift between the excitation signal and the received signal at the first frequency is less than a predeterminable limit value;
ascertaining a temperature of the medium based on a phase shift between the excitation signal and the received signal at a second frequency, wherein the second frequency is selected such that it lies in a region of a resonance width of a resonant oscillation of the coil at a maximum temperature of the medium; and
ascertaining a state indicator for the coil based on the first frequency.