METHOD AND APPARATUS FOR THE DETECTION OF CRACKS IN THE TEETH OF GENERATOR ROTORS

• US 20090071254A1
• Filed: 09/18/2008
• Published: 03/19/2009
• Est. Priority Date: 09/18/2007
• Status: Abandoned Application

• Current Assignee: Alstom Technology Ltd. (Alstom SA)
• Original Assignee: Alstom Technology Ltd. (Alstom SA)
• Inventors: Moser, Roland, Knowles, James
• Application Number:
  US12/212,681
• Publication Number:
  US 20090071254A1
• Time in Patent Office: Days
• US Class Current: 73/625
• CPC Class Codes: G01N 2291/044 Internal reflections (echoes), e.g. on walls or defects
• CPC Class Codes: G01N 2291/104 two or more emitters, one receiver
• CPC Class Codes: G01N 2291/263 Surfaces
• CPC Class Codes: G01N 2291/2693 Rotor or turbine parts
• CPC Class Codes: G01N 29/11 by measuring attenuation of acoustic waves
• CPC Class Codes: G01N 29/265 by moving the sensor relative to a stationary material

Abstract

A method for non-destructive testing the teeth of a high power electrical generator rotor includes the steps of: providing a plurality of ultrasonic pulse echo transducers (22, . . . ,25) being arranged in an array (20), and being positioned and aligned in such a way as to provide a range of different inspection angles for the tooth geometry; positioning the array (20) on top of the rotor tooth; exciting at least one of the plurality of ultrasonic pulse echo transducers (22, . . . ,25) to produce a transmission beam for the interrogation of wedge angle on the underside of the tooth; and conditioning the acquired data from the at least one of the plurality of ultrasonic pulse echo transducers (22, . . . ,25) to capture reflection from the flaws within the tooth.

Claims

1. A method for non-destructive testing the teeth of a high power electrical generator rotor, the method comprising:

providing a plurality of ultrasonic pulse echo transducers being arranged in an array, and being positioned and aligned in such a way as to provide a range of different inspection angles for the tooth geometry;

positioning the array on top of a rotor tooth;

exciting at least one of said plurality of ultrasonic pulse echo transducers to produce a transmission beam for the interrogation of wedge angle on the underside of the tooth; and

conditioning the acquired data from said at least one of said plurality of ultrasonic pulse echo transducers to capture reflection from the flaws within the tooth.

2. The method as claimed in claim 1, further comprising:

displaying the conditioned acquired data on a display.

3. The method as claimed in claim 1, wherein exciting comprises sequentially exciting the ultrasonic pulse echo transducers of said array.

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

moving the array of ultrasonic pulse echo transducers along the entirety of the tooth in the direction of the rotor axis to fully inspect the tooth.

5. The method as claimed in claim 1, wherein positioning comprises aligning the array of ultrasonic pulse echo transducers to the axial direction of the rotor tooth.

6. The method as claimed in claim 1, further comprising:

coupling the array of ultrasonic pulse echo transducers to the tooth face with a coupling medium.

7. The method as claimed in claim 4, wherein moving comprises moving the array of ultrasonic pulse echo transducers along an upper surface of the rotor tooth by a semiautomatic or fully automatic device.

8. The method as claimed in claim 7, wherein the semiautomatic or fully automatic device for moving the pulse-echo transducer array comprises an electronic encoder, which in combination with a sequential excitation of each transducer within the array, allows for data acquisition throughout the whole length of the rotor tooth.

9. The method as claimed in claim 7, wherein the semiautomatic or fully automatic device comprises a robot.

10. The method as claimed in claim 1, further comprising:

rotating the array of ultrasonic pulse echo transducers to allow inspection of an opposite side of the tooth.

11. The method as claimed in claim 1, wherein providing and positioning comprises providing and positioning two arrays of ultrasonic pulse echo transducers, and further comprising:

moving the two arrays in unity along the length of the tooth to provide full inspection of the tooth in one turn.

12. An apparatus for the non-destructive testing the teeth of a high power electrical generator rotor comprising:

a plurality of ultrasonic pulse echo transducers arranged in an array and being positioned and aligned in such a way as to provide a range of different inspection angles for tooth geometry; and

a data unit in signal communication with the plurality of ultrasonic pulse echo transducers, configured and arranged to condition data acquired from said plurality of ultrasonic pulse echo transducers.

13. The apparatus as claimed in claim 12, further comprising:

a housing;

wherein said plurality of ultrasonic pulse echo transducers is mounted in said housing.

14. The apparatus as claimed in claim 12, wherein each ultrasonic pulse echo transducers has a transducer wedge and acoustic coupling face and is arranged to provide both transmission and reception at a different predetermined angle.

15. The apparatus as claimed in claim 12, further comprising:

a device configured and arranged to carry the pulse-echo transducer array along an upper surface of the rotor tooth.

16. The apparatus as claimed in claim 15, wherein said device comprises a semiautomatic or fully automatic device.

17. The apparatus as claimed in claim 16, wherein said device comprises an electronic encoder.

18. The apparatus as claimed in claim 15, wherein the semiautomatic or fully automatic device comprises a robot.