Flow meter and method for detecting a cable fault in a cabling of the flow meter

• US 8,135,552 B2
• Filed: 04/12/2011
• Issued: 03/13/2012
• Est. Priority Date: 02/27/2006
• Status: Active Grant

• Current Assignee: Micro Motion Incorporated (Emerson Electric Company)
• Original Assignee: Micro Motion Incorporated (Emerson Electric Company)
• Inventors: Hays, Paul J, McAnally, Craig B
• Primary Examiner(s): Le, John H
• Application Number:
  US13/084,992
• Publication Number:
  US 20110185822A1
• Time in Patent Office: 336 Days
• Field of Search: 702/23, 702/45, 702/58, 702/64, 702/72, 702/85, 702/108, 702/115, 738/613.54, 324/522, 379/22.02, 701/114
• US Class Current: 702/85
• CPC Class Codes: G01F 1/8413 means for influencing the flowmeter's motional or vibrational behaviour, e.g., conduit support or fixing means, or conduit attachments
• CPC Class Codes: G01F 1/8436 signal processing
• CPC Class Codes: G01F 1/8477 with multiple measuring conduits
• CPC Class Codes: G01F 15/024 involving digital counting
• CPC Class Codes: G01F 25/10 of flowmeters

Abstract

A method for detecting a cable fault in a cabling of a flow meter is provided according to an embodiment of the invention. The method includes testing one or more first pickoff wires and one or more second pickoff wires of the cabling for pickoff open wire faults. The method further includes testing the first pickoff wires and the second pickoff wires for pickoff connection orientation faults if no pickoff open wire faults are determined in the first pickoff wires and the second pickoff wires. The method further includes testing one or more driver wires of the cabling for driver open wire faults. The method further includes testing the driver wires for a driver connection orientation fault if no driver open wire faults are determined in the driver wires.

Claims

1. A meter electronics (20) for detecting a cable fault in a cabling (205) of a flow meter (5), with the meter electronics (20) including a driver (204), first and second pickoff sensors (201a, 201b), and the cabling (205) coupled to the first and second pickoff sensors (201a, 201b) and to the driver (204), with the meter electronics (20) being characterized by:

a driver circuit (220) coupled to the cabling (205) and configured to generate a drive signal and communicate the drive signal into the cabling (205) and to the driver (204); and

a signal conditioning circuit (202) coupled to the cabling (205), with the signal conditioning circuit (202) being configured to receive at least one response signal from at least one of the first and second pickoff sensors (201a, 201b) in response to the drive signal and determine one or more of a driver open wire fault and a driver connection orientation fault in one or more driver wires of the cabling (205).

2. The meter electronics (20) of claim 1, with the signal conditioning circuit (202) being configured to compare a drive resistor voltage across a drive resistor R_D at an output of the driver circuit to a predetermined voltage threshold and determine a driver open wire fault in the one or more driver wires if the drive resistor voltage does not exceed the predetermined voltage threshold.

3. The meter electronics (20) of claim 1, with the signal conditioning circuit (202) being configured to compare a response signal phase difference to a predetermined driver phase difference threshold and determine a driver connection orientation fault in the one or more driver wires if the response signal phase difference exceeds the predetermined driver phase difference threshold, with the response signal phase difference comprising a difference between a response signal phase and a drive signal phase and with the response signal phase being received from at least one of the first pickoff sensor and the second pickoff sensor (201a, 201b).

4. The meter electronics (20) of claim 1, with the meter electronics (20) being further configured to determine a vibrational response amplitude of a vibrational response and determine a driver connection orientation fault in the one or more driver wires if the vibrational response amplitude does not substantially track a drive signal amplitude.

5. The meter electronics (20) of claim 1, wherein the driver circuit (220) is further configured to invert a drive signal if the driver connection orientation fault is determined to exist.

6. A method for detecting a cable fault in a cabling of a flow meter, the method being characterized by:

comparing a drive resistor voltage across a drive resistor R_D at an output of a driver circuit to a predetermined voltage threshold; and

determining a driver open wire fault in the one or more driver wires if the drive resistor voltage does not exceed the predetermined voltage threshold.

7. The method of claim 6, further comprising generating an alarm if the driver open wire fault is determined to exist.

8. A method for detecting a cable fault in a cabling of a flow meter, the method being characterized by:

comparing a response signal phase difference to a predetermined driver phase difference threshold, with the response signal phase difference comprising a difference between a response signal phase and a drive signal phase and with the response signal phase being received from at least one of a first pickoff sensor and a second pickoff sensor; and

determining a driver connection orientation fault in the one or more driver wires if the response signal phase difference exceeds the predetermined driver phase difference threshold.

9. The method of claim 8, further comprising generating an alarm if the driver connection orientation fault is determined to exist.

10. The method of claim 8, further comprising, after the determining, inverting a drive signal from the driver circuit if the driver connection orientation fault is determined to exist.

11. A method for detecting a cable fault in a cabling of a flow meter, the method being characterized by:

determining a vibrational response amplitude of a vibrational response; and

determining a driver connection orientation fault in the one or more driver wires if the vibrational response amplitude does not substantially track a drive signal amplitude.

12. The method of claim 11, further comprising generating an alarm if the driver connection orientation fault is determined to exist.

13. The method of claim 11, further comprising, after the determining, inverting a drive signal from the driver circuit if the driver connection orientation fault is determined to exist.

14. A method for detecting a cable fault in a cabling of a flow meter, the method being characterized by:

testing one or more first pickoff wires and one or more second pickoff wires of the cabling for pickoff open wire faults, with the one or more first pickoff wires and the one or more second pickoff wires being included in the cabling and connecting to a first pickoff sensor and to a second pickoff sensor respectively;

testing the one or more first pickoff wires and the one or more second pickoff wires for a pickoff connection orientation fault if no pickoff open wire faults are determined in the one or more first pickoff wires and the one or more second pickoff wires;

testing one or more driver wires of the cabling for a driver open wire fault, with the one or more driver wires connecting to a driver; and

testing the one or more driver wires for a driver connection orientation fault if no driver open wire faults are determined in the one or more driver wires.

15. The method of claim 14, further comprising generating an alarm if an open wire fault is determined to exist in the one or more first pickoff wires, in the one or more second pickoff wires, or in the one or more driver wires.

16. The method of claim 14, further comprising generating an alarm if a connection orientation fault is determined to exist in the one or more first pickoff wires, in the one or more second pickoff wires, or in the one or more driver wires.

17. The method of claim 14, with the testing the one or more pickoff sensors for pickoff open wire faults comprising:

comparing an injection signal component of a response signal received from at least one of the first pickoff sensor and the second pickoff sensor to a predetermined pickoff amplitude threshold; and

determining a pickoff open wire fault in a corresponding one or more first pickoff wires or in a corresponding one or more second pickoff wires if the injection signal component does not exceed the predetermined pickoff amplitude threshold.

18. The method of claim 14, with testing the one or more first pickoff wires and the one or more second pickoff wires for pickoff connection orientation faults comprising:

comparing a phase difference between a first pickoff response phase of a first pickoff response signal and a second pickoff response phase of a second pickoff response signal to a predetermined pickoff phase difference threshold, with the first pickoff response signal and the second pickoff response signal being received from the first pickoff sensor and the second pickoff sensor via the cabling; and

determining a pickoff connection orientation fault if the phase difference exceeds the predetermined pickoff phase difference threshold.

19. The method of claim 14, further comprising, after testing for the pickoff connection orientation fault, inverting the response signal from one pickoff sensor if a pickoff connection orientation fault is determined to exist.

20. The method of claim 14, with testing the driver for open wires comprising:

comparing a drive resistor voltage across a drive resistor R_D at an output of the driver circuit to a predetermined voltage threshold; and

determining a driver open wire fault in the one or more driver wires if the drive resistor voltage does not exceed the predetermined voltage threshold.

21. The method of claim 14, with testing the one or more driver wires for a driver connection orientation fault comprising:

comparing a response signal phase difference to a predetermined driver phase difference threshold, with the response signal phase difference comprising a difference between a response signal phase and a drive signal phase and with the response signal phase being received from at least one of the first pickoff sensor and the second pickoff sensor; and

determining a driver connection orientation fault in the one or more driver wires if the response signal phase difference exceeds the predetermined driver phase difference threshold.

22. The method of claim 14, with testing the one or more driver wires for a driver connection orientation fault comprising:

determining a vibrational response amplitude of a vibrational response; and

determining a driver connection orientation fault in the one or more driver wires if the vibrational response amplitude does not substantially track a drive signal amplitude.

23. The method of claim 14, further comprising, after testing the one or more driver wires for the driver connection orientation fault, inverting the drive signal from the driver if the driver connection orientation fault is determined to exist.