Multi-parameter optical fiber sensor for oil-immersed transformer

Abstract

The multi-parameter optical fiber sensor comprises a base, a probe and a probe head, the base is provided with an optical fiber connector, and the base is vertically provided with a first through hole and a second through hole in a penetrating mode; the probe is vertically arranged at the bottom of the base and communicated with the bottom end of the first through hole, and a first sensing fiber bragg grating and a second sensing fiber bragg grating are arranged in the probe in a differential distribution mode; the probe is cylindrical, is vertically arranged at the top of the base and is communicated with the top end of the second through hole, a third sensing fiber grating and a pressure film are arranged in the probe, the peripheral side of the pressure film is hermetically connected with the inner wall of the probe, the third sensing fiber grating comprises a temperature compensation grating and a pressure measurement grating which are connected in series, and the pressure measurement grating is arranged on the top surface of the pressure film. The temperature compensation grating is arranged on the inner side wall of the probe, and the first sensing fiber grating, the second sensing fiber grating and the third sensing fiber grating are respectively connected with the inlet end of the fiber connector. The problem that the temperature, the pressure and the flow velocity of the oil-immersed transformer cannot be compositely detected can be solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power and optical fiber sensing, in particular to a multi-parameter optical fiber sensor for oil-immersed transformer. BACKGROUND

[0002] Power transformer is the core component of power grid, and oil-immersed transformer is mostly used above 110kV. Transformer failure is the main cause of power plant, substation shutdown and local power grid accident. By monitoring the key parameters such as temperature and speed of transformer oil, the running condition of transformer can be grasped in real time, which is extremely important for ensuring safe operation and prolonging the life of transformer. Among them, the abnormal change of oil flow speed and oil tank pressure is often an early signal of internal failure, such as oil road blockage, pump failure or cooling system failure. Timely monitoring can detect these problems in advance and avoid more serious accidents caused by local overheating; the combination of oil flow monitoring, pressure monitoring and temperature monitoring can provide multi-dimensional safety protection for transformer to prevent electrical fire or other safety accidents caused by poor oil circulation and excessive oil tank pressure.

[0003] At present, the transformer industry generally uses traditional pressure type thermometer and pressure relief valve to measure the temperature of transformer oil surface and the pressure in transformer oil tank. However, the traditional transformer oil surface thermometer and pressure relief valve have many technical limitations when applied in transformer; first, only single parameter measurement can be realized, and the oil flow temperature and oil tank pressure in transformer cannot be detected at the same time, and the oil flow speed in transformer oil tank cannot be detected; second, the transformer pressure relief valve can only realize the identification of pressure threshold, and cannot measure the real-time pressure value in transformer oil tank.

[0004] Therefore, the present application is proposed. SUMMARY

[0005] The present application aims to provide a multi-parameter optical fiber sensor for oil-immersed transformer, which solves the problem of being unable to detect the temperature, pressure and flow rate of oil-immersed transformer.

[0006] The present application is realized by the following technical scheme: A multi-parameter optical fiber sensor for oil-immersed transformer, comprising: a base for detachable connection with an interface of a transformer oil tank, the base being provided with a fiber connector, an outlet end of the fiber connector being used for connection with an external demodulator, the base being vertically provided with a first through hole and a second through hole; a probe vertically arranged at a bottom of the base and in communication with a bottom end of the first through hole, the probe being provided with a first sensing fiber grating and a second sensing fiber grating, the first sensing fiber grating and the second sensing fiber grating being connected with an inlet end of the fiber connector respectively; a probe head in a cylindrical shape, the probe head being vertically arranged at a top of the base and in communication with a top end of the second through hole, the probe head being provided with a third sensing fiber grating and a pressure diaphragm, the pressure diaphragm being horizontally arranged and in sealed connection with an inner wall of the probe head, the third sensing fiber grating comprising a temperature compensation grating and a pressure measurement grating connected in series, the pressure measurement grating being arranged on a top surface of the pressure diaphragm, the temperature compensation grating being arranged on an inner side wall of the probe head, the temperature compensation grating and the pressure measurement grating being connected with the inlet end of the fiber connector respectively.

[0007] In another preferred embodiment, the first sensing fiber grating and the second sensing fiber grating are symmetrically packaged in the probe, the first sensing fiber grating being arranged on an inner wall of a back flow surface of the probe, and the second sensing fiber grating being arranged on an inner wall of a front flow surface of the probe.

[0008] In another preferred embodiment, the probe comprises a mounting section and a detection section, the mounting section being in a cylindrical shape, the mounting section being provided with external threads, the first through hole being provided with matching internal threads, and the mounting section being screwed with the bottom end of the first through hole, the top end of the detection section being fixedly connected with and in communication with the bottom end of the mounting section, the detection section being in a square tube shape, and the first sensing fiber grating and the second sensing fiber grating being symmetrically arranged on an inner side wall of the detection section.

[0009] In another preferred embodiment, the first sensing fiber grating and the second sensing fiber grating are pasted on the inner side wall of the detection section by epoxy, and a plane in which the first sensing fiber grating and the second sensing fiber grating are arranged is coplanar with a central axis of the detection section, and the fiber of the first sensing fiber grating and the fiber of the second sensing fiber grating are respectively led out from the top end of the mounting section and connected with the inlet end of the fiber connector through the first through hole.

[0010] In another preferred embodiment, a cap is detachably arranged on the top of the base to form a mounting cavity between the cap and the top surface of the base, the mounting cavity being in communication with the first through hole and the second through hole; the horizontal dimension of the cap is greater than that of the base; a connecting opening is formed in the sidewall of the cap to allow the mounting cavity to communicate with the external environment; the fiber connector is arranged in the mounting cavity and aligned with the connecting opening, the outlet end of the fiber connector is connected with an external demodulator through a jumper wire, the jumper wire is sleeved with a protective sleeve layer; the cap is provided with a heater.

[0011] In another preferred embodiment, the probe is in the form of a variable diameter nut, with a large diameter end and a small diameter end formed at the two ends respectively, an outer thread being formed in the outer wall of the small diameter end; the second through hole is provided with an inner thread, and the small diameter end is threadedly connected with the second through hole; the pressure film is horizontally arranged at the bottom end of the large diameter end and is in airtight connection with the inner wall of the large diameter end.

[0012] In another preferred embodiment, an outer thread is formed in the outer wall of the large diameter end; a connecting cylinder is vertically protruded from the top wall of the mounting cavity, the connecting cylinder is provided with an inner thread, and the large diameter end is threadedly connected with the connecting cylinder; a balance hole is formed through the sidewall of the bottom end of the large diameter end to allow the interior of the large diameter end to communicate with the mounting cavity, and the inner end of the balance hole is flush with the top surface of the pressure film.

[0013] In another preferred embodiment, the pressure measurement grating is adhered to the center of the top surface of the pressure film by epoxy; the temperature compensation grating is arranged in an L shape with the pressure measurement grating and is adhered to the inner sidewall of the large diameter end by epoxy.

[0014] In another preferred embodiment, the optical fiber of the third sensing fiber grating is connected with the inlet end of the fiber connector through the balance hole.

[0015] In another preferred embodiment, the heater is an electric heating sheet, and the heater is embedded in the cap.

[0016] The application has the following positive effects compared with the prior art: The application discloses a kind of for oil-immersed transformer's multi-parameter optical fiber sensor, by setting base, first through hole is opened in base, setting optical fiber connector, and by setting probe, first sensing fiber grating and second sensing fiber grating, utilize probe to extend into transformer oil, when transformer oil flows and impacts probe, probe is forced to produce elastic strain, strain is transferred to the first sensing fiber grating and second sensing fiber grating of difference distribution and encapsulated in probe, make central wavelength produce drift, the wavelength drift of two by strain generation is same, but drift direction is opposite, simultaneously, the temperature of transformer oil is by probe heat conduction to the first sensing fiber grating and second sensing fiber grating, two are located in same temperature field environment, i.e. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings, which are included to provide a further understanding of the embodiments of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings: Figure 1A schematic view of a multi-parameter optical fiber sensor for oil-immersed transformer provided by the present application; Figure 2 A semi-sectional schematic view of a multi-parameter optical fiber sensor for oil-immersed transformer provided by the present application; Figure 3 An exploded schematic view of a multi-parameter optical fiber sensor for oil-immersed transformer provided by the present application; Figure 4 A perspective schematic view of a base of a multi-parameter optical fiber sensor for oil-immersed transformer provided by the present application; Figure 5 A semi-sectional schematic view of a probe of a multi-parameter optical fiber sensor for oil-immersed transformer provided by the present application; Figure 6 A partial enlarged view of A of Figure 2 Figure 7 A partial enlarged view of B of Figure 2 Figure 8 A semi-sectional schematic view of a probe of a multi-parameter optical fiber sensor for oil-immersed transformer provided by the present application; Figure 9 A schematic view of a use state of a multi-parameter optical fiber sensor for oil-immersed transformer provided by the present application.

[0018] Markings in the drawings and corresponding names of parts: 10-base; 11-optical fiber connector; 111-jumper; 12-first through hole; 13-second through hole; 14-cap; 141-connection barrel; 15-heater; 20-probe; 201-mounting section; 202-detecting section; 21-first sensing fiber grating; 22-second sensing fiber grating; 30-probe; 301-balance hole; 31-third sensing fiber grating; 311-temperature compensation grating; 312-pressure measurement grating; 32-pressure diaphragm. DETAILED DESCRIPTION

[0019] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0020] ​​In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front", "back", "transverse", "vertical" and the like are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application, and do not indicate or imply that the device or element referred to must have a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0021] It should be particularly pointed out that "horizontal" and "vertical" in the present application are used to illustrate the approximate positional relationship, and not a strict "horizontal plane" or "vertical plane". Embodiment

[0022] Please refer to Figures 1 to 9 It is shown that the embodiment provides a kind of multi-parameter optical fiber sensor for oil-immersed transformer, including: base 10, the base 10 is used to be detachably connected with the interface of transformer oil tank, the base 10 is equipped with optical fiber connector 11, the outlet end of the optical fiber connector 11 is used to be connected with external demodulator, the base 10 is vertically through and is equipped with first through hole 12 and second through hole 13;Second including probe 20, the probe 20 is vertically arranged in the bottom of the base 10, and is communicated with the bottom end of the first through hole 12, the probe 20 is different and is equipped with first sensing fiber grating 21 and second sensing fiber grating 22, the first sensing fiber grating 21 and the second sensing fiber grating 22 are connected with the inlet end of the optical fiber connector 11 respectively;Third including probe head 30, the probe head 30 is cylindrical, the probe head 30 is vertically arranged in the top of the base 10, and is communicated with the top end of the second through hole 13, the probe head 30 is equipped with third sensing fiber grating 31 and pressure diaphragm 32, the pressure diaphragm 32 is horizontally arranged, and the periphery is sealedly connected with the inner wall of the probe head 30, the third sensing fiber grating 31 includes series-connected temperature compensation grating 311 and pressure measurement grating 312, the pressure measurement grating 312 is arranged on the top surface of the pressure diaphragm 32, the temperature compensation grating 311 is arranged on the inner side wall of the probe head 30, the temperature compensation grating 311 and the pressure measurement grating 312 are connected with the inlet end of the optical fiber connector 11 respectively.

[0023] The multi-parameter optical fiber sensor for oil-immersed transformer disclosed by the embodiment is provided with a base 10, a first through hole 12 is formed in the base 10, an optical fiber connector 11 is arranged, a probe 20, a first sensing fiber grating 21 and a second sensing fiber grating 22 are arranged, the probe 20 extends into the transformer oil, when the transformer oil flows through and impacts the probe 20, the probe 20 is forced to produce elastic strain, the strain is transmitted to the first sensing fiber grating 21 and the second sensing fiber grating 22 which are differentially distributed and encapsulated in the probe 20, the center wavelength is caused to drift, the wavelength drifts caused by the strain of the two are of the same size but opposite directions, at the same time, the temperature of the transformer oil is transmitted to the first sensing fiber grating 21 and the second sensing fiber grating 22 through the probe 20, the two are located in the same temperature field environment, that is, the wavelength drifts caused by the temperature of the transformer oil of the two are of the same size and direction, therefore, the center wavelength change amount caused by the flow rate impact can be obtained by subtracting the center wavelength drift value of the second sensing fiber grating 22 from the center wavelength drift value of the first sensing fiber grating 21, thereby realizing the measurement of the flow rate of the transformer oil, the result is twice the center wavelength change amount caused by the flow rate impact of the first sensing fiber grating 21 or the second sensing fiber grating 22; the center wavelength change amount caused by the temperature of the transformer oil can be obtained by solving the sum of the center wavelength drift value of the first sensing fiber grating 21 and the center wavelength drift value of the second sensing fiber grating 22, thereby realizing the measurement of the temperature of the transformer oil, the result is also twice the center wavelength change amount caused by the flow rate impact of the first sensing fiber grating 21 or the second sensing fiber grating 22; a second through hole 13 is formed in the base 10, a probe 30, a third sensing fiber grating 31 and a pressure diaphragm 32 are arranged, the third sensing fiber grating 31 includes a temperature compensation grating 311 and a pressure measurement grating 312 connected in series, the pressure in the transformer oil tank is transmitted to the pressure diaphragm 32 through the second through hole 13, under the action of the pressure, the pressure diaphragm 32 produces corresponding elastic strain, the strain is transmitted to the pressure measurement grating 312 encapsulated on the top surface of the pressure diaphragm 32, the center wavelength of the pressure measurement grating 312 changes correspondingly, the temperature compensation grating 311 and the pressure measurement grating 312 are in the same temperature environment, the temperature has the same influence on the two, but the temperature compensation grating 311 is not affected by the pressure, the center wavelength drift value of the temperature compensation grating 311 is measured, thereby obtaining the influence of the temperature on the center wavelength of the pressure measurement grating 312, the center wavelength drift value of the pressure measurement grating 312 is subtracted from the center wavelength drift value of the temperature compensation grating 311, thereby obtaining the center wavelength drift value of the pressure measurement grating 312 caused by the pressure, thereby realizing the measurement of the pressure in the transformer oil tank; the mutual cooperation of the above-mentioned features enables the multi-parameter optical fiber sensor for oil-immersed transformer to effectively solve the problem that the temperature, pressure and flow rate of the oil-immersed transformer cannot be detected.

[0024] In order to further explain the arrangement positions of the first sensing fiber grating 21 and the second sensing fiber grating 22, the first sensing fiber grating 21 and the second sensing fiber grating 22 are symmetrically packaged in the probe 20, the first sensing fiber grating 21 is arranged on the inner wall of the back flow surface of the probe 20, and the second sensing fiber grating 22 is arranged on the inner wall of the front flow surface of the probe 20.

[0025] In order to further explain the specific structure of the probe 20, the probe 20 comprises a mounting section 201 and a detection section 202; the mounting section 201 is in a cylindrical shape, the mounting section 201 is provided with external threads, the first through hole 12 is provided with matching internal threads, and the mounting section 201 is screwed with the bottom end of the first through hole 12; the top end of the detection section 202 is fixedly connected with the bottom end of the mounting section 201 and is in communication, the detection section 202 is in a square tube shape, and the first sensing fiber grating 21 and the second sensing fiber grating 22 are symmetrically arranged on the inner side wall of the detection section 202.

[0026] It should be noted that the hole in the middle of the probe 20 is also a square space extending in the length direction.

[0027] In order to further explain the specific connection structure of the first sensing fiber grating 21 and the second sensing fiber grating 22, the first sensing fiber grating 21 and the second sensing fiber grating 22 are pasted on the inner side wall of the detection section 202 by epoxy, and the plane where the first sensing fiber grating 21 and the second sensing fiber grating 22 are located is arranged in the same plane as the central axis of the detection section 202; the optical fiber of the first sensing fiber grating 21 and the optical fiber of the second sensing fiber grating 22 are respectively led out from the top end of the mounting section 201 and connected with the inlet end of the optical fiber connector 11 through the first through hole 12.

[0028] In order to protect the base 10 and seal the interface of the transformer oil tank, a cap 14 is detachably arranged on the top of the base 10 to form a mounting cavity between the cap 14 and the top surface of the base 10, the mounting cavity is in communication with the first through hole 12 and the second through hole 13; the horizontal size of the cap 14 is greater than the horizontal size of the base 10; the side wall of the cap 14 is provided with a connecting port to enable the mounting cavity to communicate with the external environment; the optical fiber connector 11 is arranged in the mounting cavity and is aligned with the connecting port, the outlet end of the optical fiber connector 11 is connected with an external demodulator through a jumper 111 passing through the connecting port, and the jumper 111 is sleeved with a protective sleeve layer; the cap 14 is provided with a heater 15.

[0029] The cap 14 can close the interface of the transformer oil tank, thereby effectively preventing rainwater and ensuring that the sensor surface is dry. The probe 30 is heated by the heater 15, so that the temperature inside the probe 30 is kept consistent.

[0030] To further explain the specific structure of the probe 30, the probe 30 is in the form of a variable-diameter nut, and large-diameter ends and small-diameter ends are formed at two ends, respectively. The outer wall of the small-diameter end is provided with external threads. The second through hole 13 is provided with internal threads, and the small-diameter end is screwed with the second through hole 13. The pressure diaphragm 32 is horizontally arranged at the bottom end of the large-diameter end, and the circumferential side is in sealed connection with the inner wall of the large-diameter end.

[0031] To ensure that the temperature inside the large-diameter end is balanced, the outer wall of the large-diameter end is provided with external threads. The top wall of the mounting cavity is vertically provided with a connecting cylinder 141, which is provided with internal threads. The large-diameter end is screwed with the connecting cylinder 141. The side wall of the bottom end of the large-diameter end is provided with a balance hole 301, so that the inside of the large-diameter end is in communication with the mounting cavity. The inner end of the balance hole 301 is flush with the top surface of the pressure diaphragm 32.

[0032] Through the above arrangement, the balance hole 301 is used to ensure that the pressure at the top surface of the pressure diaphragm 32 is atmospheric pressure. The connecting cylinder 141 is arranged to close the large-diameter end, so that the internal gas is heated to keep the temperature consistent.

[0033] To ensure the measurement accuracy of the pressure measurement grating 312 and the temperature compensation grating 311, the pressure measurement grating 312 is pasted to the center of the top surface of the pressure diaphragm 32 by epoxy. The temperature compensation grating 311 is arranged in an L shape with the pressure measurement grating 312 and is pasted to the inner side wall of the large-diameter end by epoxy.

[0034] To specifically explain the connection mode of the third sensing fiber grating 31 and the fiber connector 11, the fiber of the third sensing fiber grating 31 passes through the balance hole 301 and is connected with the inlet end of the fiber connector 11.

[0035] To specifically explain the heater 15, the heater 15 is an electric heating sheet, and the heater 15 is embedded in the cap 14.

[0036] The above description is only the preferred embodiment of the present application, and does not limit the implementation and protection scope of the present application. Those skilled in the art should be able to realize that any equivalent replacement and obvious changes made according to the content of the present application should be included in the protection scope of the present application.

Claims

1. A multi-parameter fiber optic sensor for oil-immersed transformers, characterized in that, include: The base (10) is used for detachable connection with the interface of the transformer tank. The base (10) is provided with an optical fiber connector (11). The outlet end of the optical fiber connector (11) is used for connection with an external demodulator. The base (10) is vertically opened with a first through hole (12) and a second through hole (13). The probe (20) is vertically disposed at the bottom of the base (10) and communicates with the bottom end of the first through hole (12). The probe (20) is provided with a first sensing fiber grating (21) and a second sensing fiber grating (22) distributed internally. The first sensing fiber grating (21) and the second sensing fiber grating (22) are respectively connected to the entrance end of the fiber optic connector (11). The probe (30) is cylindrical and is vertically mounted on the top of the base (10) and connected to the top of the second through hole (13). The probe (30) contains a third sensing fiber optic grating (31) and a pressure film (32). The pressure film (32) is horizontally mounted and its periphery is sealed to the inner wall of the probe (30). The third sensing fiber optic grating (31) includes a temperature compensation grating (311) and a pressure measurement grating (312) connected in series. The pressure measurement grating (312) is located on the top surface of the pressure film (32), and the temperature compensation grating (311) is located on the inner side wall of the probe (30). The temperature compensation grating (311) and the pressure measurement grating (312) are respectively connected to the inlet end of the fiber optic connector (11).

2. The multi-parameter fiber optic sensor for oil-immersed transformers according to claim 1, characterized in that, The first sensing fiber grating (21) and the second sensing fiber grating (22) are symmetrically encapsulated in the probe (20). The first sensing fiber grating (21) is disposed on the inner wall of the back flow surface of the probe (20), and the second sensing fiber grating (22) is disposed on the inner wall of the front flow surface of the probe (20).

3. The multi-parameter fiber optic sensor for oil-immersed transformers according to claim 2, characterized in that, The probe (20) includes an installation section (201) and a detection section (202); The mounting section (201) is cylindrical and has external threads. The first through hole (12) has matching internal threads. The mounting section (201) is screwed to the bottom end of the first through hole (12). The top end of the detection section (202) is fixedly connected to and communicates with the bottom end of the installation section (201). The detection section (202) is in the shape of a square tube. The first sensing fiber optic grating (21) and the second sensing fiber optic grating (22) are symmetrically arranged on the inner sidewall of the detection section (202).

4. The multi-parameter fiber optic sensor for oil-immersed transformers according to claim 3, characterized in that, The first sensing fiber grating (21) and the second sensing fiber grating (22) are bonded to the inner wall of the detection section (202) with epoxy adhesive. The plane containing the first sensing fiber grating (21) and the second sensing fiber grating (22) is coplanar with the central axis of the detection section (202). The optical fibers of the first sensing fiber grating (21) and the second sensing fiber grating (22) are respectively led out from the top of the mounting section (201) and connected to the entrance end of the optical fiber connector (11) through the first through hole (12).

5. The multi-parameter fiber optic sensor for oil-immersed transformers according to claim 1, characterized in that, The top of the base (10) is detachably provided with a cap (14) to form an installation cavity between the cap (14) and the top surface of the base (10), and the installation cavity communicates with the first through hole (12) and the second through hole (13); The horizontal dimension of the cap (14) is greater than the horizontal dimension of the base (10); The cap (14) has a connection port on its side wall to allow the mounting cavity to communicate with the external environment; The fiber optic connector (11) is located in the mounting cavity and aligned with the connection port. The outlet end of the fiber optic connector (11) passes through the connection port via a jumper (111) and is connected to an external demodulator. The jumper (111) is fitted with a protective sleeve. The cap (14) is equipped with a heater (15).

6. The multi-parameter fiber optic sensor for oil-immersed transformers according to claim 5, characterized in that, The probe (30) is shaped like a variable diameter nut, with a large diameter end and a small diameter end formed at both ends, and the outer wall of the small diameter end has an external thread; The second through hole (13) has an internal thread, and the small diameter end is threaded into the second through hole (13); The pressure diaphragm (32) is horizontally positioned at the bottom of the large diameter end, and its periphery is sealed to the inner wall of the large diameter end.

7. The multi-parameter fiber optic sensor for oil-immersed transformers according to claim 6, characterized in that, The outer wall of the large-diameter end is threaded. The top wall of the mounting cavity is vertically protruding with a connecting cylinder (141), the connecting cylinder (141) has an internal thread, and the large diameter end is threadedly connected to the connecting cylinder (141). A balance hole (301) is provided through the side wall at the bottom of the large-diameter end so that the interior of the large-diameter end is connected to the mounting cavity, and the inner end of the balance hole (301) is flush with the top surface of the pressure film (32).

8. The multi-parameter fiber optic sensor for oil-immersed transformers according to claim 7, characterized in that, The pressure measuring grating (312) is attached to the center of the top surface of the pressure film (32) with epoxy adhesive; The temperature compensation grating (311) and the pressure measurement grating (312) are arranged in an L-shape and are attached to the inner sidewall of the large diameter end with epoxy adhesive.

9. The multi-parameter fiber optic sensor for oil-immersed transformers according to claim 8, characterized in that, The optical fiber of the third sensing fiber grating (31) passes through the balance hole (301) and is connected to the entrance end of the optical fiber connector (11).

10. The multi-parameter fiber optic sensor for oil-immersed transformers according to claim 5, characterized in that, The heater (15) is an electric heating element, and the heater (15) is embedded in the cap (14).

Images