System to detect poor process ground connections
First Claim
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1. A field device comprising:
- a pair of electrodes coupled to a process fluid;
a diagnostic circuit coupled to the pair of electrodes to monitor a common mode signal and adapted to detect a poor ground connection associated with at least one electrode of the pair of electrodes based on line noise associated with the common mode signal; and
wherein the diagnostic circuit is adapted to detect the poor ground connection when the line noise exceeds a noise threshold.
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Abstract
A magnetic flowmeter is disclosed that includes a pair of electrodes coupled to a process fluid and a diagnostic circuit coupled to the pair of electrodes to monitor a common mode signal. The diagnostic circuit is adapted to detect a poor ground connection associated with at least one electrode of the pair of electrodes based on line noise associated with the common mode signal.
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Citations
19 Claims
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1. A field device comprising:
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a pair of electrodes coupled to a process fluid; a diagnostic circuit coupled to the pair of electrodes to monitor a common mode signal and adapted to detect a poor ground connection associated with at least one electrode of the pair of electrodes based on line noise associated with the common mode signal; and wherein the diagnostic circuit is adapted to detect the poor ground connection when the line noise exceeds a noise threshold. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A magnetic flow meter for measuring a flow rate of a fluid in a pipe, the flow meter comprising:
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a flow tube adapted to couple to a pipe to carry a fluid; a magnetic coil disposed adjacent to the flow tube to induce an electromagnetic force (EMF) within the fluid; at least two electrodes disposed within the pipe, the at least two electrodes being electrically isolated from the flowtube and one another; measurement circuitry coupled to the at least two electrodes and adapted to measure flow rate based on the induced EMF; and diagnostic circuitry coupled to the at least two electrodes to monitor a common mode signal and adapted to detect a poor electrical ground connection when line noise associated with the common mode signal exceeds a noise threshold. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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15. A magnetic flow meter comprising:
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a flow tube coupled to a pipe and adapted to carry a process fluid; first and second electrodes extending into the flow tube and coupled to the process fluid; and a diagnostic circuit coupled to the first and second electrodes to monitor a common mode signal between the first and second electrodes, the diagnostic circuit adapted to detect a poor electrical ground connection associated with at least one of the first and second electrodes when common mode line noise associated with the common mode signal exceeds a noise threshold. - View Dependent Claims (16, 17, 18, 19)
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Specification