JP2993208B2 - Temperature sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature sensor for detecting abnormal overheating of a current-carrying conductor of a power device or the like.

[0002]

2. Description of the Related Art Since a high voltage is applied to a current-carrying conductor of a power device and a large current flows, the conductor may be abnormally overheated. For this reason, a means is employed to detect abnormal overheating by attaching a thermo label to the conductor and observing a change in color from a distance, or to detect an abnormal overheating state of the conductor using a thermo camera. In addition, there are a thermocouple, a thermometer, and a thermistor for measuring the temperature of the conductor.

[0003]

As described above, in order to detect the abnormal overheating of the conductor of the power equipment as described above, the first is a thermo label and the second is a thermo camera, but the first thermo label is inexpensive. However, unless a method for detecting a color change is considered, there is a problem that monitoring cannot be performed at all times and also a problem that durability is poor.

Although the second thermo camera is expensive, it has a problem in long-term stability of the sensor portion. In addition, thermocouples, thermometers and thermistors have the problem that they cannot be directly attached to conductors due to their electrical insulation.These temperature sensors measure the temperature transmitted to gas and insulators, and therefore have low sensitivity. There is a problem, and the influence of other heat sources is great.

[0005] The present invention has been made in view of the above circumstances, provided with sensitivity with use in a wide range of temperature range higher operating correctly, the temperature sensor so as not to cause a malfunction due to electromagnetic noise The purpose is to:

[0006]

According to the present invention, in order to achieve the above object, a pair of permanent magnets are mounted in a non-magnetic case body with magnetic poles reversed, and a temperature change between the two permanent magnets. A temperature-sensitive magnetic material that changes from a ferromagnetic state to a paramagnetic state in accordance with the temperature is provided, and one end of the temperature-sensitive magnetic material is connected to one permanent magnet.
With the other end of the other permanent magnet.
Separated from the end for a certain period, at the other end of the other permanent magnet
It is characterized in that a portion in response to a temperature change from the non-magnetic casing body is fitted with a universal temperature change detector and out.

In addition, the non-magnetic case body is embedded in a heat generating conductor, a cover member for covering the temperature change detecting body is provided, and the detecting body is provided with a through hole through which light rays can pass.
At both ends of the through-hole, the ends of the optical fiber that are close to each other by penetrating the cover member are provided, and the temperature change detecting body is provided with the non-
When a part enters the magnetic material case main body , the light beam from the optical fiber is blocked.

[0008] Further, the present invention is characterized in that a lens in which light rays are hardly diffused is mounted in the through hole, and an operation inspection rod insertion hole is provided in the cover member.

[0009]

[Function] When the ambient temperature increases, the temperature-sensitive magnetic material becomes paramagnetic, and the line of magnetic force from one permanent magnet adhered to one end of the temperature-sensitive magnetic material reaches the other end of the temperature-sensitive magnetic material. Will not reach. Thereby, the other permanent magnet contacts the other end of the temperature-sensitive magnetic material. Further, when the ambient temperature decreases, the temperature-sensitive magnetic material becomes a ferromagnetic material, and separates the other permanent magnet from the temperature-sensitive magnetic material. Then, the other permanent magnet moves up and down or moves right and left. Accordingly, the temperature change detector also moves, and a part of the temperature change detector enters and exits from the case body. As a result, changes in the surroundings can be detected.

When the temperature change detector moves up and down or moves left and right, the optical path formed by the through hole of the detector and the end of the optical fiber is cut off.

Further, by mounting a lens in which a light beam is hardly diffused into a through hole provided in the temperature change detecting body, it is possible to reduce attenuation of the light beam incident on the optical fiber.

[0012]

An embodiment of the present invention will be described below with reference to the drawings. 1A and 1B, reference numeral 1 denotes a heat-generating conductor (for example, a main circuit conductor of a circuit breaker), in which a temperature sensor 2 is embedded in a hole 3. The temperature sensor 2 is configured as follows. Reference numeral 21 denotes a pipe case main body made of a non-magnetic material, and a cylindrical first permanent magnet 22 is arranged at the bottom of the pipe case main body 21. One end of a temperature-sensitive ferrite 23 which is a cylindrical Mn-Zn-based soft ferrite is bonded to the magnetic pole N of the first permanent magnet 22. The temperature-sensitive ferrite 23 has a property that a ferromagnetic material changes into a paramagnetic material when the ambient temperature rises and becomes equal to or higher than the Curie point temperature of the temperature-sensitive ferrite.

At the other end of the temperature-sensitive ferrite 24, a residual magnetic prevention plate 24 is provided. 25 is a cylindrical second permanent magnet,
The second permanent magnet 25 is housed in the case body 21 so that its magnetic pole N faces downward and has the same polarity as the magnetic pole N of the first permanent magnet 22.
Note that a nonmagnetic rod 26 penetrates through the first permanent magnet 22, the temperature-sensitive ferrite 23, and the second permanent magnet 25. Reference numeral 27 denotes a temperature change detector made of a non-magnetic material. The detector 27 is attached to the magnetic pole S of the second permanent magnet 25 so as to move up and down with the vertical movement of the second permanent magnet 25. Be composed.

A through hole 27b serving as an optical path is formed in the head 27a of the temperature change detecting body 27, and optical fibers 28a and 28b are provided near both ends of the through hole 27b. 29
Is a case that serves as a cover member that covers the temperature change detection body 27 made of a nonmagnetic material.
28b is penetrated. Reference numeral 30 denotes an optical fiber amplifier.

Next, the operation of the above embodiment will be described. As shown in FIG. 2A, when the temperature-sensitive ferrite 23 is lower than the Curie temperature, the temperature-sensitive ferrite 23 is in a ferromagnetic state from the characteristic diagram (for example, in the case of the characteristic curve C) shown in FIG. Therefore, the first
The magnetic field lines coming out of the magnetic pole N of the permanent magnet 22 return to the magnetic pole S through the temperature-sensitive ferrite 23 as shown by the arrow in FIG. 2A. Therefore, the magnetic pole at the upper end in the figure of the temperature-sensitive ferrite 23 is N. As a result, the second permanent magnet 25 is repelled, and a gap G is generated between the second permanent magnet 25 and the remanence preventing plate 24. Therefore, the temperature change detector 27
Moves upward and comes into contact with the inner surface of the case 29.

As described above, the detection body 27 is
Contact with the inner surface of the optical fiber 28a and the optical fiber 28a, 2
As a result, the light from the optical fiber 28a is transmitted to the optical fiber 28b through the through hole 27b. Thereafter, when the conductor 1 is gradually overheated due to energization or the like and becomes in an abnormally overheated state and becomes equal to or higher than the Curie point temperature, as shown in FIG. Then, the lines of magnetic force coming out of the first permanent magnet 22 do not reach the residual magnetic prevention plate 24 of the temperature-sensitive ferrite 23. For this reason, the second permanent magnet 25 falls under gravity and becomes as shown in FIG. 2B. Accordingly, the temperature change detector 27 also descends, and the light beam from the optical fiber 28a is blocked by the head 27a of the temperature change detector 27, so that no light beam enters the optical fiber 28b. In this manner, the connection of the light beam can be performed by the vertical movement of the temperature change detecting body 27.

[0017] The conditions of the length L of the temperature-sensitive ferrite to satisfy L> L _G because of FIG 4A, B.
That is, since the magnetic force of the first permanent magnet 22 is guided by the temperature-sensitive ferrite 23, when there is no temperature-sensitive ferrite 23,
The second permanent magnet 25 is longer than the gap L _G descend.
The conditions of the first and second permanent magnets 22 and 25 are shown in FIG.
As shown in (2), after the second permanent magnet 25 is pressed to contact the residual magnetic prevention plate 24, the second permanent magnet 25 is separated by the repulsive force F _R. That is, when the remanence preventing plate 24 is brought into contact with the substrate at a temperature lower than the Curie point, the repulsive force F _R and the temperature-sensitive ferrite 23
And the absorbing force of the second permanent magnet 25 has the following relationship.

[0018] In another embodiment of F _R> F _B Figure 5 is the present invention, this embodiment Case 2
9 is provided with an insertion hole 29b for inspecting the operation of the sensor in the upper wall 29a.
It is configured to be closed by 1. In this embodiment, the operation inspection rod insertion hole 29 is used to determine whether the sensor operates reliably.
When the temperature change detector 27 is forcibly depressed by pushing the operation check rod 32 from the position b, the optical fiber 28a
Is blocked by the head 27a of the temperature change detector 27. Thereby, the operation check of the sensor can be performed. If the insertion hole 29b is closed by the thermo label 31 as shown in FIG. 5, a dustproof effect can be obtained.

FIG. 6 shows an application example in which a plurality of the temperature sensors shown in FIG. 1 are provided in the optical fiber loop. When configured as shown in FIG. It can be carried out. The sensors 1 and 2 may be set to different operating temperatures. In the case of FIG. 6, it is possible to detect when one or more sensors exceed the set temperature, and it is possible to identify which sensor has operated by the color change of the thermo label.

In the embodiment shown in FIG. 1, the case where the second permanent magnet 25 is dropped by gravity has been described. However, depending on the mounting position of the sensor, a pressing spring is interposed between the temperature change detecting body 27 and the case 29. May be. Further, the side surface of the detection body 27 may be coated with aluminum or the like so that the light beam from the optical fiber is changed from the transmission type to the reflection type. Further, a through hole 27b of the temperature change detecting body 27 may be provided with, for example, a cell hook microlens for minimizing the diffusion of light rays.

[0021]

As described above, according to the present invention, the following advantages can be obtained.

(1) The temperature sensor is excellent in seismic resistance and has a stable operation with little change over time.

(2) Since the temperature sensor is small, a hole is formed in the heat-generating conductor and the hole is disposed there, and the passage of light is detected by the optical fiber type photoelectric switch. A temperature sensor is obtained.

(3) Since the temperature sensor is mounted in the hole of the heat generating conductor, the influence of the magnetic field flowing through the conductor can be eliminated.

(4) The temperature-sensitive ferrite has a high temperature sensitivity at the Curie temperature, and an accurate and stable operation can be obtained. In addition, since there is a temperature-sensitive ferrite set to various values of the Curie temperature, a temperature sensor can be easily obtained by selecting a temperature-sensitive ferrite having an appropriate Curie temperature even when used in a wide temperature range.

(5) Since the optical path opens when the temperature falls below the Curie temperature, repetitive and repetitive operations are possible, so that there is no need for replacement work like a fuse.

(6) Since the temperature characteristics of the temperature sensor are determined by the temperature-sensitive ferrite, the operating temperature can be identified by the thermo label even if the external shape is exactly the same.

(7) Since the mechanical inspection can be performed without applying a temperature to the temperature sensor, the operation check of the maintenance inspection can be easily performed.

[Brief description of the drawings]

FIG. 1A is a configuration explanatory view showing a cross section of a main part of one embodiment of the present invention, FIG.

FIG. 2A is an explanatory diagram when the temperature-sensitive ferrite is below the Curie temperature (ferromagnetic state) for explaining the principle of operation;
Is an explanatory diagram when the temperature-sensitive ferrite is above the Curie temperature (paramagnetic state),

FIG. 3 is a diagram showing a saturation magnetic flux density versus temperature characteristic of a temperature-sensitive ferrite,

FIGS. 4A and 4B are explanatory diagrams for determining a condition of a length L of a temperature-sensitive ferrite;

FIG. 5A is a cross-sectional view in a normal state showing another embodiment of the present invention, FIG.

FIG. 6 is a configuration diagram showing an application example of a temperature sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Conductor, 2 ... Temperature sensor, 3 ... Hole, 21 ... Non-magnetic pipe case main body, 22 ... 1st permanent magnet, 23 ... Temperature-sensitive ferrite, 24 ... Remaining magnetism prevention plate, 25 ... 2nd permanent magnet , 26: non-magnetic rod, 27: temperature change detector, 28a,
28b: Optical fiber, 29: Case, 31: Thermo label, 32: Operation check rod.

Continuation of front page (58) Fields investigated (Int.Cl. ⁶ , DB name) G01K 7/36 G01R 31/08

Claims (4)

(57) [Claims] 1. A temperature-sensitive device in which a pair of permanent magnets are mounted in a non-magnetic case body with their magnetic polarities reversed, and a ferromagnetic state changes to a paramagnetic state between the two permanent magnets in accordance with a temperature change. A magnetic material is provided, and one end of this temperature-sensitive magnetic material is
With the other end of the other permanent magnet.
Separated from the end for a certain period, at the other end of the other permanent magnet
A temperature sensor, wherein a portion in response to a temperature change from the non-magnetic casing body is fitted with a universal temperature change detector and out. 2. The non-magnetic case body is embedded in a heat-generating conductor, a cover member is provided to cover the temperature change detector, and a through-hole through which light rays can pass is provided in the detector. across the covering member is penetrated into the arranged ends of the optical fiber is close to the temperature change detector is the non-magnetic
2. A light shielding device according to claim 1, wherein the light from the optical fiber is blocked when a part of the body case enters.
Temperature sensor . 3. The temperature sensor according to claim 2, wherein a lens in which light rays are hardly diffused is mounted in said through hole. 4. The temperature sensor according to claim 2, wherein an operation inspection rod insertion hole for pressing the temperature change detection body is provided in the cover member.