Clamping Force Sensor Assembly For Monitoring Transformer Degradation

• US 20120247229A1
• Filed: 04/04/2011
• Published: 10/04/2012
• Est. Priority Date: 04/04/2011
• Status: Active Grant

• Current Assignee: Weidmann Electrical Technology Inc. (Wicor Holding AG)
• Original Assignee: Weidmann Electrical Technology Inc. (Wicor Holding AG)
• Inventors: Woodcock, David J.
• Granted Patent: US 8,522,626 B2
• Time in Patent Office: Days
• US Class Current: 73/862.624
• CPC Class Codes: G01L 1/242 the material being an optical fibre
• CPC Class Codes: H01F 27/402 Association of measuring or protective means

Abstract

A clamping force sensor assembly for a transformer includes at least one sensor disposed within a casing. The design and configuration of the sensor assembly is such that it accurately measures clamping force values placed on the windings, without adversely impacting the operation of the transformer and with the ability to continue operating under electrical and thermal changes within the transformer. The sensor assembly can include loading members that distribute the pressure evenly over the casing that contains the sensor. The output of the sensor can indicate to an operator the extent of pressure changes experienced by the transformer windings. The output can be coupled with a process by which the damage to or the possibility of failure of the transformer is readily evaluated.

Claims

1. A transformer comprising:

a clamped winding assembly including;

first and second end blocks disposed in spaced, opposing relationship;

at least one winding disposed between said first and second end blocks;

a plurality of insulating members disposed between said first and second end blocks;

a clamping assembly for urging said first and second end blocks toward one another so that said end blocks apply a compressive force to said at least one winding and said plurality of insulating members; and

a load sensing member including a fiber optic sensor, said load sensing member disposed adjacent, but not in direct contact with, one of (i) said at least one winding and (ii) said at least one of said plurality of insulating members so as to be subjected to said compressive force, wherein said load sensing member provides an output signal containing information regarding the magnitude of said compressive force when the transformer is energized and under a load.

2. A transformer according to claim 1, wherein said load sensing member further includes a housing and said fiber optic sensor is positioned in said housing.

3. A transformer according to claim 2, wherein each of said plurality of insulating members has a first width and a first height and wherein said housing has a second width about equal to said first width and a second height about equal to said first height.

4. A transformer according to claim 2, wherein each of said plurality of insulating members has a first compressibility and wherein said housing has a second compressibility that is less than said first compressibility.

5. A transformer according to claim 2, wherein said load sensing member is configured to transmit light into said housing, to receive an altered light emission from said housing, and to produce said output signal based on the differences between said transmitted light and said altered light emission.

6. A transformer according to claim 1, wherein said load sensing member is positioned adjacent at least one of said first and second end blocks.

7. A transformer according to claim 1, wherein said load sensing member is positioned adjacent said at least one winding.

8. A clamping force sensor for use in a transformer having a clamping assembly including first and second end blocks, a plurality of windings, and a plurality of insulating members having a first compressibility, the first and second end blocks, plurality of windings, and plurality of insulating members being arranged such that a compressive force can be applied to compress the clamping assembly along an axis traveling through the first and second end blocks, the plurality of windings, and the plurality of insulating members, said clamping force sensor comprising:

a housing defining a chamber, wherein said housing has a first height substantially the same as that of one or more of the plurality of insulating members within the clamping assembly, further where said housing has a second compressibility that is less than the first compressibility; and

a fiber optic sensor coupled to said chamber to measure changes in compressibility when the transformer is energized and under load.

9. A clamping force sensor according to claim 8, wherein said fiber optic sensor provides an output signal containing information regarding the magnitude of said compressive force.

10. A clamping force sensor according to claim 8, wherein said housing has a first width, further wherein each of said plurality of insulating members has a second width about equal to said first width and a second height about equal to said first height.

11. A clamping force sensor according to claim 8, wherein said fiber optic sensor is configured to transmit light into said housing, to receive an altered light emission from said housing, and to produce said output signal based on the differences between said transmitted light and said altered light emission.

12. A clamping force sensor according to claim 8, wherein said fiber optic sensor includes a interferometric type fiber optic transducer.

13. A clamping force sensor for replacing one or more of a plurality of insulating members within a transformer, wherein each of the plurality of insulating members has a first width and is capable of transmitting a compressive force substantially uniformly across the first width when the transformer is energized and under load, the clamping force sensor comprising:

a housing defining a chamber, wherein said housing has a second width that is about equal to the first width such that the housing substantially uniformly transmits the compressive force to at least one of said plurality of insulating members; and

a fiber optic sensor positioned within said chamber so as to determine changes in the shape of said chamber, wherein said fiber optic sensor transmits an output signal representative of said changes in shape of said chamber.

14. A clamping force sensor according to claim 13, wherein each of the plurality of insulating members has a first compressibility and wherein said housing has a second compressibility that is less than said first compressibility.

15. A clamping force sensor according to claim 13, wherein each of the plurality of insulating members has a first width and a first height and wherein said housing has a second width about equal to said first width and a second height about equal to said first height.

16. A clamping force sensor according to claim 13, wherein said fiber optic sensor is configured to transmit light into said housing, to receive an altered light emission from said housing, and to produce said output signal based on the differences between said transmitted light and said altered light emission.

17. A clamping force sensor according to claim 13, wherein said fiber optic sensor includes a interferometric type fiber optic transducer.

18. A method of determining a real time compression of windings within a transformer that is energized and under load comprising:

measuring an initial compression force exerted on a clamping assembly with a clamping force sensor installed within the clamping assembly;

determining a difference in compression force from the initial compression force;

and

indicating a status of the clamping assembly based on the difference in compression force.

19. A method according to claim 18, wherein said determining is based upon changes in the shape of a housing containing a fiber optic sensor.

20. A method according to claim 18, wherein said determining is completed in situ and during the operation of the transformer.

21. A method according to claim 18, further including determining the frequency of changes of compression force and indicating a status of the clamping assembly based upon said frequency of changes.

22. A transformer monitoring system for a transformer that is energized and under load, the monitoring system comprising:

a clamped winding assembly compressed by a compression force, said clamped winding assembly including;

a plurality of insulating members radially arranged on a plurality of planes within said clamped winding assembly; and

a load sensing member having a fiber optic sensor, said load sensing member disposed adjacent at least one of said plurality of insulating members so as to be subjected to said compressive force, wherein said load sensing member provides an output signal containing information regarding the magnitude of said compressive force when the transformer is energized and under load; and

a controller coupled to said load sensing member and configured to;

receive said output signal;

compare said information to an alert trigger;

determining a status of said clamped winding assembly based on said comparison.