IP Library › Granted Patent US 11,451,171

Granted Patent B2

US 11,451,171 · App. 16/446,050 · Granted Sep 20, 2022

Motor branch circuit health monitoring method

Inventors: Kevin M. Jefferies (Raleigh, NC); Benjamin W. Edwards (Rolesville, NC); Alan E. Freeman (Raleigh, NC); Richard K Weiler (Wake Forest, NC); Matthew L. White (Cary, NC)

Assignee: Schneider Electric USA, Inc.

H02P1/26

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Quick Facts

Patent No.: US 11,451,171
App. No.: 16/446,050
Granted: Sep 20, 2022
Kind: B2

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Abstract

Techniques for monitoring the health of a three-phase induction motor are provided. An expected threshold value is calculated as a function of an expected ratio of current unbalance to voltage unbalance for the three-phase motor. Embodiments determine whether a measured current unbalance exceeds the expected threshold value. Responsive to the measured current unbalance exceeding the expected threshold value, a remedial action may be taken, such as generating diagnostic information or activating one or more protection operations for the three-phase induction motor.

Claims (108)

1. A method, comprising:

calculating, by a three-phase protective device, an expected current unbalance, as a product of a measured voltage unbalance times an expected ratio of current unbalance to voltage unbalance for a three-phase load;

calculating, by the three-phase protective device, an expected threshold current unbalance indicating a potential fault caused by unbalanced currents, as the expected current unbalance plus a value of unbalance tolerance/sensitivity;

determining, by the three-phase protective device, whether a measured current unbalance exceeds at least one of the expected current unbalance or the expected threshold current unbalance;

performing, by the three-phase protective device, a protection operation relating to a motor protection relay for the three-phase load, based on the determination;

calculating, by the three-phase protective device, a second expected current unbalance for a three-phase induction motor, as the product of the measured voltage unbalance times an expected ratio of current unbalance to voltage unbalance for the three-phase induction motor;

determining, by the three-phase protective device, that a sum of the measured current unbalance and a product of the measured voltage unbalance times the second expected ratio of current unbalance to voltage unbalance for the three-phase induction motor, exceeds a predetermined fraction of the expected threshold current unbalance; and

providing, by the three-phase protective device, diagnostic information warning of a potential fault condition for the three-phase induction motor.

2. The method of claim 1 , further comprising:

determining, by the three-phase protective device, that the measured current unbalance exceeds the expected current unbalance; and

providing, by the three-phase protective device, diagnostic information for the three-phase load, based on the determination.

3. The method of claim 1 , wherein performing the protection operation further comprises providing, by the three-phase protective device, protection for the three-phase load, based on the determination.

4. The method of claim 1 , further comprising:

calculating, by the three-phase protective device, the expected current unbalance for a three-phase induction motor, as the product of the measured voltage unbalance times an expected ratio of current unbalance to voltage unbalance for the three-phase induction motor;

determining, by the three-phase protective device, that the measured current unbalance exceeds the expected current unbalance; and

providing, by the three-phase protective device, diagnostic information warning of a potential fault condition for the three-phase induction motor.

5. The method of claim 1 , further comprising:

calculating, by the three-phase protective device, the expected threshold current unbalance indicating a potential fault caused by unbalanced currents, as the calculated expected current unbalance of the three-phase induction motor plus a value of unbalance tolerance/sensitivity for the three-phase induction motor;

determining, by the three-phase protective device, that the measured current unbalance exceeds the expected threshold current unbalance; and

providing, by the three-phase protective device, protection for the three-phase load, based on the determination.

6. The method of claim 1 , further comprising:

determining, by the three-phase protective device, that that the measured current unbalance exceeds the expected threshold current unbalance; and

delaying, by the three-phase protective device, providing protection for the three-phase induction motor, for a duration based on whether the three-phase induction motor is in the start state or the run state.

7. An apparatus, comprising:

at least one processor;

at least one memory including computer program code, wherein the computer program code, when executed by operation of the at least one processor, performs an operation comprising:

determining, by the three-phase protective device, whether a measured current unbalance exceeds at least one of the expected current unbalance or the expected threshold current unbalance;

performing, by the three-phase protective device, a protection operation relating to a motor protection relay for the three-phase load, based on the determination;

providing, by the three-phase protective device, diagnostic information warning of a potential fault condition for the three-phase induction motor.

8. The apparatus of claim 7 , further comprising:

the at least one memory including computer program code, wherein the computer program code, when executed by operation of the at least one processor, performs an operation further comprising:

determining, by the three-phase protective device, that the measured current unbalance exceeds the expected current unbalance; and

providing, by the three-phase protective device, diagnostic information for the three-phase load, based on the determination.

9. The apparatus of claim 7 , wherein performing the protection operation further comprises providing, by the three-phase protective device, protection for the three-phase load, based on the determination.

10. The apparatus of claim 7 , further comprising:

the at least one memory including computer program code, wherein the computer program code, when executed by operation of the at least one processor, performs an operation further comprising:

determining, by the three-phase protective device, that the measured current unbalance exceeds the expected current unbalance; and

providing, by the three-phase protective device, diagnostic information warning of a potential fault condition for the three-phase induction motor.

11. The apparatus of claim 7 , further comprising:

the at least one memory including computer program code, wherein the computer program code, when executed by operation of the at least one processor, performs an operation further comprising:

determining, by the three-phase protective device, that the measured current unbalance exceeds the expected threshold current unbalance; and

providing, by the three-phase protective device, protection for the three-phase load, based on the determination.

12. The apparatus of claim 7 , further comprising:

the at least one memory including computer program code, wherein the computer program code, when executed by operation of the at least one processor, performs an operation further comprising:

determining, by the three-phase protective device, that that the measured current unbalance exceeds the expected threshold current unbalance; and

13. A computer program product comprising computer executable program code recorded on a computer readable non-transitory storage medium, the computer executable program code comprising:

code for calculating, by a three-phase protective device, an expected current unbalance, as a product of a measured voltage unbalance times an expected ratio of current unbalance to voltage unbalance for a three-phase load;

code for calculating, by the three-phase protective device, an expected threshold current unbalance indicating a potential fault caused by unbalanced currents, as the expected current unbalance plus a value of unbalance tolerance/sensitivity;

code for determining, by the three-phase protective device, whether a measured current unbalance exceeds at least one of the expected current unbalance or the expected threshold current unbalance;

code for performing, by the three-phase protective device, a protection operation relating to a motor protection relay for the three-phase load, based on the determination;

code for calculating, by the three-phase protective device, a second expected current unbalance for a three-phase induction motor, as the product of the measured voltage unbalance times an expected ratio of current unbalance to voltage unbalance for the three-phase induction motor;

code for determining, by the three-phase protective device, that a sum of the measured current unbalance and a product of the measured voltage unbalance times the second expected ratio of current unbalance to voltage unbalance for the three-phase induction motor, exceeds a predetermined fraction of the expected threshold current unbalance; and

code for providing, by the three-phase protective device, diagnostic information warning of a potential fault condition for the three-phase induction motor.

14. The computer program product of claim 13 , further comprising:

code for determining, by the three-phase protective device, that the measured current unbalance exceeds the expected current unbalance; and

code for providing, by the three-phase protective device, diagnostic information for the three-phase load, based on the determination.

15. The computer program product of claim 13 , wherein the code for performing the protection operation further comprises code for providing, by the three-phase protective device, protection for the three-phase load, based on the determination.

16. The computer program product of claim 13 , further comprising:

code for calculating, by the three-phase protective device, the expected current unbalance for a three-phase induction motor, as the product of the measured voltage unbalance times an expected ratio of current unbalance to voltage unbalance for the three-phase induction motor;

code for determining, by the three-phase protective device, that the measured current unbalance exceeds the expected current unbalance; and

code for providing, by the three-phase protective device, diagnostic information warning of a potential fault condition for the three-phase induction motor.

17. The computer program product of claim 13 , further comprising:

code for calculating, by the three-phase protective device, the expected threshold current unbalance indicating a potential fault caused by unbalanced currents, as the calculated expected current unbalance of the three-phase induction motor plus a value of unbalance tolerance/sensitivity for the three-phase induction motor;

code for determining, by the three-phase protective device, that that the measured current unbalance exceeds the expected threshold current unbalance; and

code for providing, by the three-phase protective device, protection for the three-phase load, based on the determination.

18. A method, comprising:

determining, by the three-phase protective device, whether a measured current unbalance exceeds at least one of the expected current unbalance or the expected threshold current unbalance;

providing, by the three-phase protective device, a protection operation relating to a motor protection relay for the three-phase load, based on the determination;

calculating, by the three-phase protective device, a second expected threshold current unbalance indicating a potential fault caused by unbalanced currents, as the second calculated expected current unbalance of the three-phase induction motor plus a value of unbalance tolerance/sensitivity for the three-phase induction motor;

determining, by the three-phase protective device, that the second measured current unbalance exceeds the second expected threshold current unbalance; and

19. An apparatus, comprising:

at least one processor;

at least one memory including computer program code, wherein the computer program code, when executed by operation of the at least one processor, performs an operation comprising:

determining, by the three-phase protective device, whether a measured current unbalance exceeds at least one of the expected current unbalance or the expected threshold current unbalance;

providing, by the three-phase protective device, a protection operation relating to a motor protection relay for the three-phase load, based on the determination;

determining, by the three-phase protective device, that the second measured current unbalance exceeds the second expected threshold current unbalance; and

20. A computer program product comprising computer executable program code recorded on a computer-readable non-transitory storage medium, the computer executable program code, when executed, configured to perform an operation comprising:

determining, by the three-phase protective device, whether a measured current unbalance exceeds at least one of the expected current unbalance or the expected threshold current unbalance;

providing, by the three-phase protective device, a protection operation relating to a motor protection relay for the three-phase load, based on the determination;

determining, by the three-phase protective device, that the second measured current unbalance exceeds the second expected threshold current unbalance; and

Assignments (1)

ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Aug 15, 2019

From: JEFFERIES, KEVIN M.; EDWARDS, BENJAMIN W.; WEILER, RICHARD K.; WHITE, MATTHEW L.; FREEMAN, ALAN E.

To: SCHNEIDER ELECTRIC USA, INC.

Reel/Frame 050061/0323 →

Continuity (1)

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