JPH0666649A - Optical fiber temperature sensor - Google Patents

Abstract

PURPOSE:To allow the long term measurement of temperature at a live part while ensuring safety by protecting an optical fiber against high voltage. CONSTITUTION:Looped part 1a of an optical fiber 1 is contained in a metal case 3 from which end part of the optical fiber 1 is taken out and pulsating light is passed through the optical fiber 1 in order to detect temperature at a live part based on the intensity of Raman backscattered light. The case 3 is covered with a dielectric 2 such as silicon resin and electrically insulated from a heat plate 4 abutting directly on the live part. The metal case 3 is connected with a grounding lead wire 7 thus preventing application of voltage onto the optical fiber 1. The heat plate 4 is made of a good thermal conductor, e.g. copper, having a fixing hole 8 for fixing the heat plate 4 to a live part through bolts and nuts. The heat plate 4 has a partially exposed part 4a and the residual part is coated 2a with the dielectric 2 so that influence of ambient temperature is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber temperature sensor using an optical fiber as a temperature sensor, and more particularly to a spot sensor for detecting the temperature of a charging section.

[0002]

2. Description of the Related Art Conventionally, no-fuse breaker (NFB)
An optical fiber temperature sensor is known as a spot sensor for measuring the temperature of a charging part of a high voltage busbar. This is made by winding a few meters of optical fiber into a coil and contacting the charging part.
The temperature of the charging part is detected from the intensity of Raman backscattered light generated by the pulsed light incident on the optical fiber.

[0003]

When the temperature of the charging section is measured by the optical fiber temperature sensor, it is necessary to bring the optical fiber, which is a sensor serving as a temperature sensing section, into contact with the charging section. The optical fiber is an electrical insulator and can maintain electrical insulation even if the optical fiber is brought into contact with the charging part for a short period of time.

However, it is known that if the optical fiber is left for a long time in a state where a voltage is applied, the electrical insulation of the surface of the optical fiber is deteriorated and dielectric breakdown occurs along the surface of the optical fiber. Therefore, measuring the temperature of the charging unit with the optical fiber temperature sensor for a long period of time has a problem in terms of safety. Until now, the temperature of the charging unit has been measured with the optical fiber temperature sensor for a long period of time. Things weren't done.

However, the optical fiber temperature sensor has the advantage that it is not affected by electromagnetic noise, and is suitable for monitoring the temperature of the charging section of electrical equipment. Therefore, there is a high potential demand for measuring the temperature of the charging part for a long term using an optical fiber temperature sensor.

An object of the present invention is to allow the temperature of the charging section to be transmitted to the optical fiber even without contact, and to make the optical fiber groundable. An object of the present invention is to provide an optical fiber temperature sensor capable of safely measuring temperature over a long period of time.

[0007]

The optical fiber temperature sensor of the present invention is attached to the charging section, and the temperature of the charging section is determined from the Raman backscattered light intensity generated by the pulsed light incident on the coiled optical fiber. In an optical fiber temperature sensor for detecting, a grounding means that enables grounding of a coiled optical fiber, and an electrical insulator that covers substantially the entire coiled optical fiber including this grounding means, The heat insulating plate is provided so that at least a part of the electric insulator is exposed, and a part of the heat contact plate comes into contact with the charging part and transfers the heat of the charging part to the optical fiber. is there.

In this case, the grounding means stores the entire coiled optical fiber in a conductive case,
It may be grounded via a grounding electrode or a grounding lead wire attached to this case, or the outer circumference of the coiled optical fiber may be covered with a metal tube to ground it, or A ground wire may be integrally provided along the line. Further, a plurality of heat transfer plates may be provided so as to be electrically insulated so as to be attached to a plurality of charging parts. Furthermore, it is preferable to provide a mounting hole in a part of the heat transfer plate exposed from the electrical insulator.

[0009]

When the coiled optical fiber is grounded by the grounding means, and the entire coiled optical fiber including the grounding means is covered with an electrical insulator, the optical fiber of the charging section is Since no voltage is applied, the electrical insulation of the surface of the optical fiber does not deteriorate even when the sensor is subjected to measurement for a long period of time, and a dielectric breakdown does not occur along the surface of the optical fiber.

Further, when at least a part of the heat transfer plate having a good thermal conductivity is exposed from the electrical insulator, the heat of the charging section can be efficiently transferred to the optical fiber through the exposed section. Further, since the heat transfer plate is provided in contact with the grounding means, the optical fiber does not need to receive the voltage from the charging section.

[0011]

【Example】

[First Embodiment] FIG. 1 shows the arrangement of an optical fiber temperature sensor according to the first embodiment of the present invention. The optical fiber 1 has a loop portion 1a wound several times in a coil shape and is housed in a metal case 3 made of stainless steel or brass. The metal case 3 has a flat shape as illustrated. The optical fiber 1 is fixed in the metal case 3 by, for example, fixing a tension member 5 made of Kevlar (registered trademark of DuPont) fiber with a tension member fixing jig 6. Both ends of the optical fiber 1 are taken out from the end of the metal case 3, and the temperature of the charging part can be detected from the intensity of Raman backscattered light generated when pulsed light is incident on the optical fiber 1.

The metal case 3 is covered with an electric insulator 2 made of silicon resin or the like, excluding the end portion from which the optical fiber 1 is taken out, or including the end portion, and the heat transfer plate is in direct contact with the charging portion. It is electrically insulated from 4. Also,
A grounding lead wire 7 is connected to the metal case 3 so as to be directly drawn out from the case 3. When actually used, grounding the grounding lead wire 7 prevents the optical fiber 1 from being applied with a voltage. To The metal case 3 and the grounding lead wire 7 constitute a grounding means for grounding the coiled optical fiber.

The heat transfer plate 4 is formed of a good heat conductor such as copper or aluminum, and a mounting hole 8 is formed in a part thereof, and the mounting hole 8 is used to, for example, a terminal of a high voltage busbar or a no-fuse breaker. It can be securely fixed to the charging part of the unit with bolts and nuts. Mounting holes 8 for such fixing
In order to provide the heat transfer plate 4 with the heat transfer plate 4, the heat transfer plate 4 has an exposed portion 4a that is partially projected from the electric insulator 2. The remaining portion of the heat transfer plate 4 is covered with the insulator 2 in order to make it less likely to be affected by the ambient temperature other than the charging portion,
That is, it is provided as the covering portion 2a, and as a result, the rest is in the form of being embedded in the electric insulator 2. Therefore, the size of the electrical insulator 2 is made wider than the width of the heat transfer plate 4 so that the rest of the heat transfer plate 4 can be embedded.

Since the electric insulator 2 can be easily made of a material having excellent electric insulation characteristics by using silicon resin or the like, the optical fiber temperature sensor according to the present embodiment can be safely used for a long period of time. Further, the portion of the electric insulator covering the covering portion 2a of the heat transfer plate 4 may be made of the same material as the other insulating portions, but the purpose of providing the covering portion 2a It is preferable to use a material having a low thermal conductivity for the part and a material having a good thermal conductivity for the other part.

In the loop portion 1a in the metal case 3, the optical fiber is in the core state in order to reduce the size of the loop portion. However, the optical fiber 1 outside the metal case 3 is a light fiber as shown in FIG. The fiber-shaped core wire 11, a tension member 5 made of Kevlar fiber provided on the outside thereof, and a vinyl sheath 12 that covers the tension member 5 are cord-shaped.

As described above, according to this embodiment, the entire optical fiber 1 used as the temperature sensor is covered with the metal case 3 having the grounding lead wire 7, and the periphery of the metal case 3 is used in contact with the charging section. It is covered with an electrical insulator 2 so that no voltage is applied to the optical fiber 1 when measuring the temperature of the charging part. Further, even if the charging part is small, the part directly contacting the charging part is made of a good heat conductor such as copper or aluminum so that the temperature of the charging part is efficiently transmitted to the loop part 1a of the optical fiber 1 of the temperature sensing part. The structure is such that a good conductor is attached to the electric insulator 2. If a material having a good electrical insulation property is used as the good thermal conductor, the good electrical insulation between the good thermal conductor and the metal case 3 need not be particularly considered. Therefore,
Since no high voltage is applied to the optical fiber, the electrical insulation of the surface of the optical fiber does not deteriorate, and the dielectric breakdown does not occur along the surface of the optical fiber. as a result,
Even if the temperature of the charging part is measured with an optical fiber temperature sensor for a long period of time, there is no problem in terms of safety, and the advantage of the optical fiber temperature sensor is that it is not affected by electromagnetic noise. It can be applied to the temperature monitoring of the charging section, and can sufficiently meet the potential demand for long-term measurement of the temperature of the charging section using an optical fiber temperature sensor.

[Second Embodiment] In the first embodiment described above,
Although the ground wire 7 was directly drawn from the metal case 3, the ground wire 7 is housed in the optical fiber 1 to
It is also possible to integrate the and the ground wire 7. In this case, the grounding wire 7 extends outside the case and is connected to the sheath 1 with the optical fiber core wire 11 by an optical fiber splicing box or the like to which the grounding wire 7 is drawn.
The part taken out from 2 will be grounded to the metal case of the junction box. In this way, by integrating the optical fiber core wire 11 and the ground wire 7, the optical fiber temperature sensor 30
It is possible to reduce the number of apparent lead wires pulled out from the sensor and to simplify the periphery of the sensor mounting portion.
As the structure of the optical fiber in this case, as shown in FIG. 3, the optical fiber core wire 11 is housed in the metal tube 20 having the insulating coating 21 or in the sheath 12 as shown in FIG. A structure in which a ground wire 22 made of copper, aluminum, or the like is held is conceivable. In this way, if the metal tube and the ground wire are housed in the optical fiber and the optical fiber is used in the loop portion 1a with the metal tube and the ground wire still attached, the metal case 3 for grounding itself can be omitted. Is also possible.

[Third Embodiment] As shown in FIG. 5, a metal case 3 for accommodating the loop portion 1a of the optical fiber 1 is formed in an annular shape, and the outer periphery thereof is covered with an electric insulator 2. Then, the heat transfer plate 4 having the mounting holes 8 formed therein is composed of a collar-shaped circular head portion and a cylindrical body portion, and the body portion is fitted into the annular hole,
It is also possible to have a structure in which the head is locked to the upper surface of the electrical insulator 2. In this case, the central mounting hole 8 can be used to attach to a charging part such as a high voltage busbar with a bolt or the like.

[Fourth Embodiment] In the above-described embodiments, the case where one temperature sensor measures the temperature of one charging portion has been described. However, as shown in FIG. (3 in the illustrated example) heat transfer plates 4a, 4b, 4
By adopting the structure in which c ... Is attached, the temperatures of the charging parts at a plurality of locations can be collectively measured. When three pieces are attached as in the illustrated example, the heat transfer plates 4a, 4b, 4c of the temperature sensor are connected to the three charging portion terminals of the three-phase breaker.
By connecting each of them, the temperature of the entire breaker can be monitored by one temperature sensor. in this case,
If the minimum bend radius of the loop portion 1a of the optical fiber 1 is equal to or larger than the allowable bend radius of the optical fiber 1, the optical fiber 1 can be bent into an elliptical shape as shown in FIG. The advantage is that the sensor size in the left-right direction in FIG. 6 can be reduced.

It is to be noted that mounting a plurality of heat transfer plates electrically insulated from each other on one temperature sensor makes it possible to use a sensor having another shape, for example, a temperature sensor having a shape as shown in FIG. Can be easily applied

[0021]

According to the present invention, the temperature of the charging portion can be measured safely and accurately over a long period of time without considering the electrical insulation performance of the optical fiber itself.

[Brief description of drawings]

FIG. 1 is a plan view and a sectional view of an optical fiber temperature sensor for measuring a temperature of a charging portion according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the optical fiber according to the first embodiment.

FIG. 3 is a sectional view showing a structural example of an optical fiber in which a ground wire is integrated according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view showing another structural example of the optical fiber in which the ground wire is integrated according to the second embodiment of the present invention.

FIG. 5 is a plan view and a sectional view of an optical fiber temperature sensor according to a third embodiment of the present invention.

FIG. 6 is a plan view of an optical fiber temperature sensor according to a fourth embodiment of the present invention.

[Explanation of symbols]

 1 Optical Fiber 2 Electrical Insulator 3 Metal Case 4 Heat Transfer Plate 5 Tension Member 6 Tension Member Fixing Jig 7 Ground Lead Wire 1a Optical Fiber Loop Part 11 Optical Fiber Core Wire 12 Sheath 20 Metal Tube 21 Insulation Coating 22 Ground Wire 30 Optical fiber temperature sensor

Claims (5)

[Claims] 1. An optical fiber temperature sensor for detecting the temperature of a charging part from the intensity of Raman backscattered light generated by pulsed light incident on a coiled optical fiber attached to the charging part. A grounding means capable of grounding the wound optical fiber, an electric insulator covering substantially the whole of the coiled optical fiber including the grounding means, and at least a part of the electric insulator being exposed. An optical fiber temperature sensor, comprising: a heat transfer plate having a good thermal conductivity, the heat transfer plate being provided on a part of the heat transfer plate and contacting the charging part to transfer heat of the charging part to the optical fiber. 2. The grounding means comprises a conductive case for accommodating the entire coiled optical fiber, and a grounding electrode or a grounding lead wire attached to the case for grounding the case. The fiber optic temperature sensor of claim 1 constructed. 3. The grounding means covers the outer circumference of the coiled optical fiber with a metal tube so as to ground it, or a grounding wire is integrally provided along the optical fiber. The optical fiber temperature sensor according to claim 1, configured as described above. 4. The optical fiber temperature sensor according to claim 1, wherein a plurality of the heat transfer plates are provided so as to be electrically insulated so as to be attached to a plurality of charging units. 5. The optical fiber temperature sensor according to claim 1, wherein a mounting hole is provided in a part of the heat transfer plate provided so as to be exposed from the electrical insulator.