METHOD AND SYSTEM FOR DETECTING ROTOR FAULT

• US 20170082692A1
• Filed: 03/24/2015
• Published: 03/23/2017
• Est. Priority Date: 12/30/2013
• Status: Active Grant

• Current Assignee: ABB Schweiz AG (ABB Limited)
• Original Assignee: ABB Schweiz AG (ABB Limited)
• Inventors: Mulay, Prasad, Orman, Maciej, KRISHNAMOORTHI, Karthik, Pinto, Cajetan, Rzeszucinski, Pawel
• Granted Patent: US 10,353,004 B2
• Time in Patent Office: Days
• CPC Class Codes: G01R 29/0814 Field measurements related to measuring influence on or from apparatus, components or humans EMC, EMI and similar testing in general G01R31/001, e.g. in ESD, EMI, EMC, EMP testing, measuring radiation leakage; detecting presence of micro- or radiowave emitters; dosimetry; testing shielding; measurements related to lightning
• CPC Class Codes: G01R 31/343 in operation
• CPC Class Codes: G01R 33/04 using the flux-gate principle
• CPC Class Codes: G01R 33/10 Plotting field distribution ; Measuring field distribution

Abstract

In aspects, the present invention discloses a method of detecting a rotor fault in an electric machine using a data analysis unit. The method comprises measuring magnetic field strength along a first axis and a second axis, determining operating slip frequency of the electric machine using the measured magnetic field strength along the first axis and the second axis, determining an amplitude of the determined operating slip frequency in a first frequency spectrum and an amplitude of operating slip frequency in a second frequency spectrum, and detecting the rotor fault by comparing the amplitude of the determined operating slip frequency in the first frequency spectrum and the amplitude of operating slip frequency in the second frequency spectrum against a predetermined threshold.

Claims

1. A method of detecting a rotor fault in an electric machine 110 using a data analysis unit 120, the method comprising:

a. measuring magnetic field strength along a first axis and a second axis, wherein the first axis is at a first angle to the axis of the rotor of the electric machine and the second axis is at a second angle to the axis of the rotor of the electric machine;

b. determining operating slip frequency of the electric machine 110 using the measured magnetic field strength along the first axis and the second axis, wherein determining operating slip frequency comprises

i. generating a first frequency spectrum from the measured magnetic field strength along the first axis and a second frequency spectrum from the magnetic field strength along the second axis;

ii. identifying a peak within a predetermined range in at least one of the first frequency spectrum and the second frequency spectrum; and

iii. determining a frequency corresponding to the identified peak within the predetermined range, in at least one of the first frequency spectrum and the second frequency spectrum;

c. determining an amplitude of the determined operating slip frequency in the first frequency spectrum and an amplitude of operating slip frequency in the second frequency spectrum; and

d. detecting the rotor fault by comparing the amplitude of the determined operating slip frequency in the first frequency spectrum and the amplitude of operating slip frequency in the second frequency spectrum against a predetermined threshold.

2. The method as claimed in claim 1, further comprising determining type of the detected rotor fault by comparing the amplitude of the determined operating slip frequency in the first frequency spectrum with the amplitude of operating slip frequency in the second frequency spectrum, and determining severity of the detected rotor fault by based on the amplitude of the determined operating slip frequency in the first frequency spectrum and the amplitude of operating slip frequency in the second frequency spectrum.

3. The method as claimed in claim 1, further comprising calculating the predetermined range based on a nominal slip frequency associated with the electric machine 110 and a nominal line frequency associated with the electric machine 110.

4. The method as claimed in claim 1, further comprising

a. measuring magnetic field strength along a third axis, wherein the third axis is at a third angle to the first axis;

b. generating a third frequency spectrum from the measured magnetic field strength along the third axis;

c. identifying a peak within a predetermined range in the third frequency spectrum;

d. determining a frequency corresponding to the identified peak within the predetermined range, in the third frequency spectrum; and

e. comparing the determined frequency against the determined operating slip frequency for detecting fault in a magnetic field sensor from the one or more magnetic field sensors.

5. A system for detecting a rotor fault in an electric machine 110, the system comprising:

a. a data analysis unit 120, comprising;

i. one or more magnetic field sensors for measuring magnetic field strength along a first axis and a second axis, wherein the first axis is substantially parallel to the axis of the rotor of the electric machine and wherein the second axis is at an angle to the first axis;

ii. a network interface configured to communicate with a remote service device 130;

iii. one or more processors configured to

1. generate a first frequency spectrum and a second frequency spectrum from the measured magnetic field strength along the first axis and the second axis;

2. identify a peak within a predetermined range in at least one of the first frequency spectrum and the second frequency spectrum;

3. determine operating slip frequency corresponding to the identified peak

4. detect the rotor fault based on an amplitude of the determined operating slip frequency in the first frequency spectrum and an amplitude of operating slip frequency in the second frequency spectrum; and

iv. a memory module operatively coupled to the one or more processors.

6. The system as claimed in claim 5, wherein the data analysis unit 120 is affixed on the frame of the electric machine 110, substantially close to the drive side bearing of the electric machine 110.

7. The system as claimed in claim 5, wherein the one or more processors are further configured to determine type and severity of the detected rotor fault based on the amplitude of the determined operating slip frequency in the first frequency spectrum and the amplitude of operating slip frequency in the second frequency spectrum.