US20060215730A1

Movatterモバイル変換

Info

Publication number: US20060215730A1
Application number: US11/354,292
Authority: US
Inventors: Jean-Francois Meilleur; Jean-Noel Berube; Michel Plourde
Original assignee: Neoptix Inc
Current assignee: Neoptix Inc
Priority date: 2005-02-14
Filing date: 2006-02-14
Publication date: 2006-09-28
Also published as: US20090213898A1; US8568025B2

Abstract

A temperature probe for use in oil-filled transformers comprises an optical fiber, a temperature sensitive member, and a protective cylindrical sheath. The optical fiber and the sensitive member are located in the protective sheath, and continuous longitudinal slit is defined along the length of the sheath to allow oil to flow therein. The optical fiber is mounted in and to the sheath using a bonding material and at a distance from the sheath. The sensitive member is adhesively mounted to the optical fiber, within the sheath, and at a distance thereof.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This Application claims priority on U.S. Provisional Patent Application No. 60/651,980 filed on Feb. 14, 2005, which is herein incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to temperature probes for oil-filled power transformers and, more particularly, to fiber optic temperature probes.

BACKGROUND OF THE INVENTION

Temperature probes are used in many applications, including in oil-filled power transformers. Such temperature probes can have an optical fiber extending within a sheath, and with a spiral wrap. The temperature sensitive element is generally held in position on the outside of the sheath with an epoxy bubble. Diagonal or perpendicular slits are defined in the sheath.

There is a need to provide a fiber optic temperature probe that allows the oil to flow properly into the sheath so as to reach the optical fiber.

There is also a need to provide a fiber optic temperature probe wherein stress is reduced on the temperature sensitive element.

The present invention seeks to meet this and other needs.

SUMMARY OF THE INVENTION

The present invention relates to a fiber optic temperature probe that aims at overcoming the drawbacks of known fiber optic temperature probes.

It is therefore an aim of the present invent into provide a novel fiber optic temperature probe, typically for use in oil-filled power transformers.

Therefore, in accordance with the present invention, there is provided a temperature probe, typically for use in oil-filled transformers, comprising an optical fiber, a temperature sensitive member, and a protective sheath, the optical fiber and the sensitive member being located in the protective sheath, the sheath defining at least one substantially longitudinal slit so as to allow oil to flow into the sheath.

Also in accordance with the present invention, there is provided a temperature probe, typically for use in oil-filled transformers, comprising an optical fiber, a temperature sensitive member, and a protective sheath, the optical fiber and the sensitive member being located in the protective sheath.

Further in accordance with the present invention, there is provided a temperature probe, typically for use in oil-filled transformers, comprising an optical fiber, a temperature sensitive member, and a protective sheath, the sensitive member being mounted to the optical fiber and the optical fiber being mounted to the protective sheath.

Having described the invention generally, illustrative embodiments of the fiber optic temperature probe of the present invention will be described hereinbelow together with the drawings. The illustrative embodiments should not be construed as a limitation of the present invention but only as exemplified and non-limiting embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made to the accompanying drawings, showing by way of illustration an illustrative embodiment of the present invention, and in which:

FIG. 1 is a longitudinal cross-sectional view of part of a fiber optic temperature probe in accordance with an illustrative embodiment of the present invention;

FIG. 2 is a perspective view of the fiber optic temperature probe ofFIG. 1, with proximal parts of a sheath tube and of an optical cable of the temperature probe being fragmented for illustration purposes;

FIG. 3 is a diametrical cross-sectional view of a sheath tube of the fiber optic temperature probe ofFIGS. 1 and 2, the sheath tube protecting an optical cable of the temperature probe and defining herein a continuous slit; and,

FIG. 4 is side elevational view of the fiber optic temperature probe of the present invention.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS OF THE INVENTION

The present invention is illustrated in further details by the following non-limiting examples.

In accordance with the present invention, there is herein illustrated a fiber optic temperature probe P, which is typically used in oil-filled power transformers.

The temperature probe P includes anoptical fiber10 that extends longitudinally within an outerprotective sheath tube11. Thesheath tube11 defines slit, herein illustratively shown as acontinuous slit12, that is a slit that extends the whole length of thesheath tube11. Thecontinuous slit12, which is well shown inFIGS. 2 and 3, allows dielectric oil contained in the power transformer to reach the inside of the temperature probe P.

Abonding material13 is provided inside thesheath tube11 to mount theoptical fiber10 to the inside surface of thesheath tube11. Thebonding material13 herein has an annular configuration to surround theoptical fiber10 and ensure its position inside thesheath tube11. The bondingmaterial13 can be epoxy, a silicone adhesive, a polymer, a fluoropolymer, and any other suitable bonding or mounting material.

Thesheath tube11 has a chemically-etched or mechanically-modified innercircumferential area16 for improved bonding of the bondingmaterial13 to the inside surface of thesheath tube11. This is particularly desirable when theprotective sheath tube11 is made out of a hard to bond material, such as fluoropolymers including PTFE (polytetrafluoroethylene), FEP (fluorinated ethylene-propylene) and PFA (phenol-formaldehyde adhesive).

The chemically-etched or mechanically-modifiedarea16 is of variable length depending on the location needed for the bonding of theoptical fiber10. The chemically-etched or mechanically-modifiedarea16 is located substantially at the tip of thesheath tube11, as shown inFIG. 1, and can proximally start at the beginning of thesheath tube11, or not.

The fiber optic temperature probe P also includes a temperature-sensitive element14 that induces a change of optical properties according to a given temperature. A light signal is sent is to the temperature-sensitive element14 through theoptical fiber10. The light that is returned from the temperature-sensitive element14 carries changes of characteristics, such as, but not limited to, wavelength, intensity or interferences. The temperature probe mates with an optical signal conditioner which decodes such a new light profile and converts it into engineering units.

The temperature-sensitive element14 can take on various geometrical forms (e.g. disc, square, tubular, octagonal, etc.). The temperature-sensitive element14 is bonded, as seen inFIG. 1, to the distal end of theoptical fiber10 using anappropriate adhesive15. The temperature-sensitive element14 is then bonded to thesheath tube11 with epoxy, silicone adhesives or fluoropolymers at the location of the chemically-etched or mechanically-modifiedarea16 of thesheath tube11.

Thesheath tube11 can have an outer dimension, herein outer diameter, ranging, for instance, between 0.3 mm and 10 mm. Thesheath tube11 can be made of polymers plastics and, as previously mentioned, fluoropolymers such as PTFE, FEP, PFA, Hydrel™, Tefzel™, polyimide and similar materials. Thesheath tube11 can be of any color or opacity. When thesheath tube11 is made out of PTFE fluoropolymers (Teflon™) materials, temperature probe design and construction allow for the use of temperature probes at service temperatures of up to 260° C.

The fiberoptic cable10 can be of any size, type (monomode or multimode) and material. An optical connector18 (shown inFIG. 4) is attached to a proximal end of theoptical fiber10 andsheath tube11, i.e. the end opposite to the distal end shown inFIGS. 1 and 2 and that houses the temperaturesensitive element14. Proximally of thesheath tube11 shown generally inFIGS. 1 and 2, the temperature probe P has a reinforcement spiral wrap19 (shown inFIG. 4) that, for instance, is made of PTFE Teflon™ and has a diameter of 3.1 mm.

The fiber optic temperature probe P can be as long as it is possible to manufacture thesheath tube11 with its continuouslongitudinal slit12. It is also possible to use a sheath tube that has multiple longitudinal sections instead of one continuouslongitudinal slit12. The continuouslongitudinal slit12 allows for the flow of dielectric oil into the temperature probe P, thus fillingvoid gaps17 defined within thesheath tube11.

From the foregoing, the probe P of the present invention, compared with existing fiber optic temperature probes for oil-filled transformers, provides a more robust, a more oil permeable sheath as well as a more economical design. This results from thesheath tube11 provided over theoptical fiber10 and that defines thecontinuous slit12 along the whole length of the tube wall and by bonding theoptical fiber10, instead of thesensitive element14, to thesheath tube11. Furthermore, the temperaturesensitive element14 is located inside thesheath tube11, as opposed to being, as in known probes, located exteriorly of the sheathing tube, thereby providing a more robust design.

Fiber optic temperature probes, to be compatible with high voltage environmental conditions present inside a power transformer, must be free of any air gaps or foreign particulates. This sensor is usually attached to the inner parts of the transformer, such as bushings, windings, oil conduits, radiator, top/bottom of tank, etc. The present probe P allows for a substantially optimal flow of the dielectric oil into the whole probe P.

Compared to known fiber optic temperature probes, the present probe P has the following characteristics. The probe P has theprotective sheath tube11 over theoptical fiber10 with the continuouslongitudinal slit12 that allows oil to migrate into thesheath11. Thesensitive element14 is free inside thesheath tube11, with no bonding that can cause stress or deformation (mechanical or optical) of thesensitive element14. Theoptical fiber10 is bonded to theprotective sheath tube11 near the opticallysensitive element14 with high temperature epoxy, silicon or fluoropolymers. Theprotective sheath11 is chemically-etched (or mechanically-modified) on its inner wall before receiving thebonding adhesive13. The present probe P is easier and more economical to manufacture because thesheath tube11 is already slit on its entire length, thereby avoiding the additional operation for allowing the oil to access the inside of the sheath such as diagonal or perpendicular slits as in known probes.

Aside from the above characteristics, the probe P can be manufactured in considerable lengths without breakage (e.g. up to 25 meters), as there are no mechanical operations to effect on thesheath tube11, such as the operation of defining perpendicular slits in known probes. Also, the present simpler design requires less manipulation, such as thesensitive element14 that is simply manufactured by simply bonding theoptical fiber10 to thesheath tube11. Furthermore, the present probe P provides a robust protective sheath design as there is no mechanical degradation of theprotective sheath tube11 such as seen with known sheathings having multiple diagonal or perpendicular slits and where these slits may degrade the sheath's ability to protect the optical fiber during transformer manufacturing. Moreover, the present probe P provides a robustsensitive element14 as, since thesensitive element14 is embedded inside thesheath tube11, which is an enclosed sensitive tip, there is no risk of thesensitive element14 becoming detached during manipulation and installation (in known methods involving external bonding, there is created a protuberance around the sensitive element, which may act as a handle or grip that can thus allow force to detach such sensitive element).

The present invention can take on various other configurations, and examples thereof follow hereinbelow.

Thelongitudinal slit12 can, as previously mentioned, be in multiple sections instead of being continuous. The location of these longitudinal slit sections can be anywhere on the circumference of thesheath tube11.

Different materials, sizes and interconnections can be used for the components.

It is possible not to use the chemically-etched or mechanically-modified innercircumferential area16 on the entire interior surface of thesheath tube11 if the material used for thesheath tube11 is reputed to be easy to bond.

Thebonding material13 used to attach theoptical fiber10 to thesheath tube11 can also cover completely thesensitive element14.

There can be multiple chemically-etched or mechanically-modified innercircumferential areas16 provided at more than one location along thesheath tube11.

A chemically-etched or mechanically-modified innercircumferential area16 can also be provided on the exterior surface of thesheath tube11.

Although the present invention has been described hereinabove by way of specific embodiments thereof, it may be modified, without departing from the spirit and nature of the subject invention as defined in the appended claims.

Claims

1. A temperature probe for use in fluid-filled transformers, comprising an optical fiber, a temperature sensitive member, and a protective sheath, the optical fiber and the sensitive member being located in the protective sheath, the sheath defining at least one substantially longitudinal slit so as to allow fluid to flow into the sheath.

2. A temperature probe as defined inclaim 1, wherein the sheath is tubular.

3. A temperature probe as defined inclaim 1, wherein the slit is a single continuous slit.

4. A temperature probe as defined inclaim 3, wherein the continuous slit extends substantially a length of the protective sheath.

5. A temperature probe as defined inclaim 1, wherein the optical fiber is mounted in the sheath using a bonding material.

6. A temperature probe as defined inclaim 5, wherein the optical fiber is mounted with the bonding material at a distance from the sheath.

7. A temperature probe as defined inclaim 1, wherein the sensitive member is mounted to the optical fiber.

8. A temperature probe as defined inclaim 7, wherein the sensitive member is mounted substantially at a distal end of the optical fiber and at a distance from the sheath.

9. A temperature probe comprising an optical fiber, a temperature sensitive member, and a protective sheath, the optical fiber and the sensitive member being located in the protective sheath.

10. A temperature probe as defined inclaim 9, wherein the sensitive member is mounted to the optical fiber within the sheath.

11. A temperature probe as defined inclaim 10, wherein the sensitive member is mounted substantially at a distal end of the optical fiber.

12. A temperature probe as defined inclaim 10, wherein the sensitive member is spaced from the sheath.

13. A temperature probe as defined inclaim 10, wherein the sensitive member is mounted to the optical fiber with an adhesive.

14. A temperature probe as defined inclaim 9, wherein the optical fiber is mounted to the sheath using a bonding material and at a distance from the sheath.

15. A temperature probe comprising an optical fiber, a temperature sensitive member, and a protective sheath, the sensitive member being mounted to the optical fiber and the optical fiber being mounted to the protective sheath.

16. A temperature probe as defined inclaim 15, wherein the optical fiber is mounted in the sheath using a bonding material.

17. A temperature probe as defined inclaim 16, wherein the optical fiber is mounted with the bonding material at a distance from the sheath.

18. A temperature probe as defined inclaim 15, wherein the sensitive member is spaced from the sheath.

19. A temperature probe as defined inclaim 15, wherein an inside surface of the sheath is treated for better adherence of the bonding material thereto.

20. A temperature probe as defined inclaim 19, wherein the inside surface of the sheath is at least one of chemically-etched and mechanically-modified.