MAGNETIC FLOWMETER WITH SATURATION DETECTION AND/OR PREVENTION
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Abstract
A magnetic flowmeter for measuring flow of a process fluid in a pipe includes a magnetic coil disposed adjacent to the pipe configured to apply a magnetic field to the process fluid. First and second electrodes are disposed within the pipe and electrically coupled to the process fluid and configured to sense an electromotive force (EMF) induced in the process fluid due to the applied magnetic field and flow of the process fluid. Input circuitry is coupled to the first and second electrodes and provides an output related to the sensed EMF. Diagnostic circuitry coupled to the input circuitry is configured to identify a saturation related condition and responsively provide a diagnostic output. In another embodiment, saturation prevention circuitry prevents saturation of the input circuitry.
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Citations
40 Claims
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1-21. -21. (canceled)
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22. A magnetic flowmeter for measuring flow of a process fluid in a pipe, the flowmeter comprising:
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a magnetic coil disposed adjacent to the pipe configured to apply a magnetic field to the process fluid; first and second electrodes disposed within the pipe which are electrically coupled to the process fluid and configured to sense an electromotive force (EMF) induced in the process fluid due to the applied magnetic field and flow of the process fluid; input circuitry electrically coupled to the first and second electrodes having an output related to the sensed EMF; and saturation prevention circuitry configured to prevent saturation of the input circuitry due to a offset voltage between the first and second electrodes. - View Dependent Claims (23, 24, 26, 27, 28, 29, 30, 31, 32)
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25. The apparatus of claim 25 wherein the voltage offset is an AC voltage offset.
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33. A method for measuring flow of a process fluid in a pipe, comprising:
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applying a magnetic field to process fluid flowing through the pipe with a magnetic coil; sensing an electromotive force (EMF) induced in the pipe due to the applied magnetic field and flow of the process fluid using first and second electrodes; measuring the EMF with input circuitry, the measured EMF indicative of flow of the process fluid; and preventing saturation of the input circuitry due to an offset voltage between the first and second electrodes. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40)
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Specification