METHOD OF ON-LINE AUTOMATIC GENERATOR CORE THROUGH-BOLT TENSIONING

• US 20140305223A1
• Filed: 04/16/2013
• Published: 10/16/2014
• Est. Priority Date: 04/16/2013
• Status: Abandoned Application

• Current Assignee: Siemens Energy Incorporated (Siemens AG)
• Original Assignee: Siemens Energy Incorporated (Siemens AG)
• Inventors: Twerdochlib, Michael, Thompson, Edward David, Diatzikis, Evangelos V.
• Application Number:
  US13/863,426
• Publication Number:
  US 20140305223A1
• Time in Patent Office: Days
• US Class Current: 73/800
• CPC Class Codes: B23P 19/067 Bolt tensioners for hand tools B25B29/02
• CPC Class Codes: F16B 31/028 with a load-indicating washer or washer assembly
• CPC Class Codes: G01B 11/18 using photoelastic elements
• CPC Class Codes: G01D 5/35316 using a Bragg gratings
• CPC Class Codes: G01L 1/246 using integrated gratings, e.g. Bragg gratings
• CPC Class Codes: G01L 5/243 using washers
• CPC Class Codes: G01N 3/08 by applying steady tensile or compressive forces G01N3/28 takes precedence
• CPC Class Codes: G02B 6/02076 Refractive index modulation gratings, e.g. Bragg gratings
• CPC Class Codes: H02K 1/16 Stator cores with slots for windings
• CPC Class Codes: H02K 11/20 for measuring, monitoring, testing, protecting or switching rectifiers H02K11/04; power electronics H02K11/33

Abstract

A generator stator core that includes a plurality of through-bolts extending through the stator core. Each through-bolt includes a threaded end on which is positioned a conical washer and a through-bolt nut, where the through-bolt nuts are tightened against the washers to compress laminate plates and hold the stator core together. The stator core further includes a through-bolt tension monitoring system including a fiber Bragg grating sensor mounted to one or more of the conical washers and being provided in at least one optical fiber. The monitoring system further includes a monitoring device providing an optical signal to each of the fiber Bragg grating sensors and receiving a reflected signal from the fiber Bragg grating sensors where the reflected signal provides an indication of strain on the washer to provide an indication of how tight the nut is on the through-bolt.

Claims

1. A generator stator core comprising:

a plurality of circular plates positioned adjacent to each other to form a stator column;

a plurality of through-bolts circumferentially disposed around the stator column and extending through the circular plates from one end of the column to an opposite end of the column, each through-bolt including a threaded end on which is positioned a conical washer and a through-bolt nut, wherein the through-bolt nuts on the through-bolts are tightened against the washers to compress the circular plates and hold the stator column together; and

a through-bolt tension monitoring system including a fiber Bragg grating sensor for each through-bolt, each fiber Bragg grating sensor provided in at least one optical fiber and being mounted to the conical washer, said system further including a monitoring device providing an optical signal to each of the fiber Bragg grating sensors and receiving a reflected signal from the fiber Bragg grating sensors where the reflected signal provides an indication of strain on the washer to provide an indication of how tight the nut is on the through-bolt.

2. The stator core according to claim 1 wherein the fiber Bragg grating sensor is positioned on an inside surface of the washer.

3. The stator core according to claim 1 wherein the fiber Bragg grating sensor is positioned on an outside surface of the washer.

4. The stator core according to claim 1 wherein all of the fiber Bragg grating sensors are provided in a single optical fiber.

5. The stator core according to claim 1 wherein each fiber Bragg grating sensor for each through-bolt is provided in a separate optical fiber.

6. The stator core according to claim 1 further comprising at least one temperature Bragg grating sensor provided in the at least one optical fiber and providing an indication of temperature to the monitoring device.

7. The stator core according to claim 1 wherein the monitoring device is positioned out of the stator core environment.

8. The stator core according to claim 1 wherein the monitoring device is positioned within the stator core environment.

9. A system for monitoring tension on one or more through-bolts extending through and compressing laminate plates of a generator stator core, each through-bolt including a through-bolt nut that is threaded onto the through-bolt against the nut, wherein at least one of the through-bolts includes a conical washer that the through-bolt nut is tightened against, said system comprising:

at least one fiber Bragg grating sensor mounted to the conical washer of a through-bolt and being provided in at least one optical fiber; and

a monitoring device providing an optical signal to the at least one fiber Bragg grating sensor and receiving a reflected signal from the fiber Bragg grating sensor that provides an indication of strain on the washer to provide an indication of how tight the nut is on the through-bolt.

10. The system according to claim 9 wherein each through-bolt includes a fiber Bragg grating sensor.

11. The system according to claim 10 wherein all of the fiber Bragg grating sensors are provided in a single optical fiber.

12. The system according to claim 10 wherein each fiber Bragg grating sensor for each through-bolt is provided in a separate optical fiber.

13. The system according to claim 9 wherein the at least one fiber Bragg grating sensor is positioned on an inside surface of the washer.

14. The system according to claim 9 wherein the at least one fiber Bragg grating sensor is positioned on an outside surface of the washer.

15. The system according to claim 9 further comprising at least one temperature Bragg grating sensor provided in the at least one optical fiber and providing an indication of temperature to the monitoring device.

16. The system according to claim 9 wherein the monitoring device is positioned out of the stator core environment.

17. The system according to claim 9 wherein the monitoring device is positioned within the stator core environment.

18. A generator stator core comprising:

a plurality of laminate plates positioned adjacent to each other to form a stator column;

a plurality of through-bolts circumferentially disposed around the stator column and extending through the laminate plates from one end of the column to an opposite end of the column, each through-bolt including a threaded end on which is positioned a through-bolt nut, wherein the through-bolt nuts on the through-bolts are tightened to compress the circular plates and hold the stator column together, and wherein at least one of the through-bolts includes a conical washer that the through-bolt nut is tightened against; and

a through-bolt tension monitoring system including at least one fiber Bragg grating sensor for at least one of the through-bolts where the through bolt that includes a fiber Bragg grating sensor also includes a conical washer, wherein the at least one fiber Bragg grating sensor is provided in at least one optical fiber and being mounted to the conical washer, said system further including a monitoring device providing an optical signal to the at least one fiber Bragg grating sensor and receiving a reflected signal from the at least one fiber Bragg grating sensor where the reflected signal provides an indication of strain on the washer to provide an indication of how tight the nut is on the through-bolt.

19. The stator core according to claim 18 wherein each through-bolt includes a conical washer and a fiber Bragg grating sensor.

20. The stator core according to claim 18 wherein the at least one fiber Bragg grating sensor is positioned on an inside surface or an outside surface of the washer.