JP2003098015A - Thermocouple circuit test method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect even a connection polarity error at an even-numbered spot in a thermocouple circuit test. SOLUTION: The temperature of one of connection spots 5-7 in a thermocouple circuit constituted by connecting successively a thermocouple 2, a thermocouple side cable 8 (8a, 8b), a metal conductor 9 (9a, 9b) of a cable penetration 4, an instrument side cable 10 (10a, 10b), and an indicator/recorder 3, is set at a different temperature from those of other connection spots 5-7, and propriety of the connection state thereof is tested by the change of the indicator/ recorder 3 at that time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermocouple circuit test method for a thermocouple circuit formed by connecting a thermocouple and an indicator or a recorder by a plurality of cables.

[0002]

2. Description of the Related Art Conventionally, thermocouples have been used for measuring the temperature inside a nuclear reactor containment vessel (PCV) and the temperature of each equipment.

The thermocouple is formed by point-joining two kinds of metal conductors, and the temperature is measured by utilizing the fact that a thermoelectromotive force is generated according to the difference in temperature at the joint point. .

In the previous case, the thermocouple was placed in the PCV,
The indicator or recorder is installed outside the PCV, and these are connected by a cable to form a thermocouple circuit.
The temperature at the measuring point inside V can be displayed or recorded outside PCV.

This will be described with reference to FIG. The thermocouple circuit is composed of a thermocouple 2 and a PC arranged inside the PCV1.
Indicator / recorder 3 arranged outside V1, cable penetration 4 provided with metal conductors 9 (9a, 9b) buried through the wall of PCV1, each metal conductor 9 of cable penetration 4 and thermocouple The thermocouple side cable 8 (8a, 8b) for connecting to 2 and the instrument side cable 10 (10a, 10b) for connecting the respective metal conductors 9 of the cable penetration 4 and the indicator / recorder 3 to each other. .

The metal conductors 9, the thermocouple-side cables 8 and the instrument-side cables 10 of the cable penetration 4 are formed of a combination of metals of the same type as the thermocouple 2 to be connected.

In the drawings used in the present specification such as FIG. 1, these two kinds of metals are indicated by thick lines and thin lines. The thick line is the + pole of the thermocouple 2 (connection point 5a side)
Shows the same metal as, and the thin wire is the negative pole of thermocouple 2 (connection point 5
The description will be given assuming that the same metal as the (b side) is shown.

[0008] These connections are made by an operator when installing or replacing the thermocouple, and then a thermocouple circuit test (soundness confirmation test) to check whether the thermocouples are correctly connected is performed in the following procedure.

First, in order to confirm the soundness of the thermocouple 2, the temperature near the measuring point measured by the thermocouple 2 is measured by another calibrated thermometer, and the value is indicated / recorded. Confirm that it is equal to the indicated value of 3 in total.

If the value measured by another thermometer is equal to the value indicated by the indicator / recorder 3, it can be confirmed that at least the thermocouple 2 is operating normally.

Next, in order to confirm that the connection between the thermocouple 2 and the indicator / recorder 3 is correct, the connection between the terminal portion 5 (5a, 5b) of the thermocouple 2 and the thermocouple side cable 8 is made. To disconnect the thermocouple circuit.

When the thermocouple circuit is opened, the indicator / recorder 3
Since no signal is input to, the indicated value should be zero. Therefore, if the indicator / recorder 3 of the open thermocouple circuit shows zero, it can be confirmed that the thermocouple circuit is a circuit including the target thermocouple 2 and the indicator / recorder 3.

Next, in order to confirm that the polarities are correctly connected at the connection points in the thermocouple circuit, a voltage generator (not shown) was connected to the terminal portion 5 of the thermocouple 2 to simulate thermoelectromotive force. Applying a simulated voltage to the indicator /
Check the change in the indicated value on the recorder 3.

For example, when the positive terminal of the thermocouple 2 and the negative terminal of the indicator / recorder 3 are connected, the indicated value of the indicator / recorder 3 is opposite to the simulated voltage change. To show the change. Therefore, increase (or decrease) the simulated voltage
If the indicated value also increases (or decreases) with this, it can be confirmed that the polarity of the circuit is correct.

With the above, the thermocouple circuit test is completed, the voltage generator is removed from the terminal portion 5 of the thermocouple 2, and the thermocouple side cable 8 that has been separated is connected to the terminal portion 5 to restore the thermocouple circuit.

[0016]

However, in the thermocouple circuit test method described above, it is not possible to detect if the connection polarity error occurs even times as shown in FIG. There was a problem that it was detected only when the car was driven and the usage environment changed.

That is, in the configuration shown in FIG. 2, the metal conductor 9b of the cable penetration 4 and the thermocouple side cable 8a are connected, and the metal conductor 9a of the cable penetration 4 and the instrument side cable 8b are connected. The connection polarity is incorrect twice.

If the connection polarity is wrong at an odd number of times, it can be judged from the fact that the indicator value of the indicator / recorder 3 changes in reverse when the above-mentioned simulated voltage is changed. When it occurs twice, the indication value of the indicator / recorder 3 is reversed, and it becomes impossible to confirm the connection error after all.

Therefore, it is an object of the present invention to provide a thermocouple circuit test method capable of detecting such a connection error in a thermocouple circuit test and improving the reliability of the test.

[0020]

In order to solve the above-mentioned problems, the invention according to claim 1 is such that the output of a thermocouple arranged on one side through a wall such as a partition wall is installed on the other side. When the temperature is measured by inputting it to the indicator or recorder, it consists of a thermocouple and the same type of metal wire, a cable penetration embedded in the wall, and a thermocouple and the same type of metal wire, and a thermocouple. It consists of a thermocouple side cable that connects to the cable penetration, and a set of thermocouple and the same kind of metal wire,
In a thermocouple circuit test method for performing a connection test of a thermocouple circuit configured by an instrument side cable connecting the cable penetration and an indicator or a recorder, a thermocouple,
Thermocouple side cable, cable penetration, meter side cable, and the temperature of one connection point in the indicator or recorder is set to a temperature different from the temperature of the other connection point, from the change of the indicator or recorder at that time, The suitability of these connection states is determined.

As a result, by making the temperature of one connection point different from the temperature of the other connection points, the difference in the temperature is reflected in the indicator value of the indicator or the recorder. Is also characterized in that the reliability of the test is improved by enabling detection in the thermocouple circuit test.

According to the second aspect of the present invention, the thermocouple, the thermocouple side cable, the cable penetration, the instrument side cable, and one of the connection points in the indicator or recorder are heated to a temperature different from the temperature of the other connection points. Then, the suitability of these connection states is judged from the change of the indicator or recorder at that time.

According to the third aspect of the present invention, the thermocouple, the thermocouple side cable, the cable penetration, the instrument side cable, and one connection point in the indicator or the recorder are irradiated with light from the projector to heat them. The temperature of the connection point is set to a temperature different from the temperature of other connection points, and the suitability of these connection states is determined from the change of the indicator or the recorder at that time.

In the invention according to claim 4, the thermocouple, the thermocouple side cable, the cable penetration, the instrument side cable, and one connection point in the indicator or recorder are cooled to a temperature different from the temperature of the other connection points. Then, the suitability of these connection states is judged from the change of the indicator or recorder at that time.

According to a fifth aspect of the present invention, the thermocouple, the cable on the thermocouple side, the cable penetration, the cable on the instrument side, and the connection point of one on the indicator or the recorder are sprayed with a cooling spray to cool them. It is characterized in that the temperature of the connection point is set to a temperature different from the temperatures of the other connection points, and the suitability of these connection states is judged from the change of the indicator or recorder at that time.

The invention according to claim 6 is characterized in that the wall is a partition wall of the reactor containment vessel.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. First, the principle of the present invention will be described. Since the thermocouple circuit has the same configuration as that shown in FIG. 1 and the like, the same reference numerals are used and the description thereof is appropriately omitted.

A general potential relationship in such a thermocouple circuit is as follows: the thermoelectromotive force generated by the thermocouple 2 is V0, and the thermoelectromotive force at the connection points 5-7 is V5a, V5b, V6a, V.
6b, V7a, V7b and the voltage input to the indicator / recorder 3 is Vt: Vt = V0 + V5a + V5b + V6a + V6b + V7a + V7b (Equation 1)

In the connected state shown in FIG. 1, the thermocouple 2
The positive electrode of the thermocouple 2 and the indicator / recorder 3 are sequentially connected by a thermocouple side cable 8a made of metal, a metal conductor 9a, and a meter side cable 10a, and the negative electrode of the thermocouple 2 and the indicator / recorder 3 are connected. Between the recorder 3 and the thermocouple-side cable 8b made of metal, a metal conductor 9b, and the instrument-side cable 10 shown by thin lines.
They are sequentially connected by b.

As a result, since the connection points 5-7 are made of the same metal, no thermoelectromotive force is generated at the connection points 5-7 regardless of the temperature.

Therefore, as shown in FIG. 3, V5a, V5
b, V6a, V6b, V7a and V7b are all zero, Vt = V0, and the thermoelectromotive force generated in the thermocouple 2 is input to the indicator / recorder 3.

On the other hand, in the case of the connection state shown in FIG. 2, a thermocouple side cable 8a made of a metal shown by a thick line and a metal shown by a thin line are provided between the + pole of the thermocouple 2 and the indicator / recorder 3. And a meter-side cable 10a made of a metal indicated by a thick line, and a thermocouple side cable 8b made of a metal indicated by a thin line between the negative electrode of the thermocouple 2 and the indicator / recorder 3. , A metal conductor 9 made of a metal indicated by a thick line
a, a meter-side cable 10b made of metal indicated by a thin line, and connected in order.

As a result, the connection point 5 is made of the same kind of metal, but the connection points 6 and 7 are made of different kinds of metals.

Therefore, as shown in FIG.
As described above, since the thermoelectromotive force is not generated regardless of the temperature as described above, V5a and V5b are zero, but the thermoelectromotive force is generated at the connection points 6 and 7.

At the connection point 6, a thermoelectromotive force in the opposite direction to V0 is generated, so V6a = -V6a,
V6b = -V6b.

If the connection points 6a and 6b and the connection points 7a and 7b are provided close to each other, the same temperature can be considered at these connection points, so V6a = V6b, V7a = V7b. Is established. Again, V6a = V6b = V6, V7a = V7b
= V7.

Substituting these relationships into Equation 1,   Vt = V0-V6a-V6b + V7a + V7b       = V0-2xV6 + 2xV7 (Formula 2) Becomes

During the connection work, the inside and outside of the PCV are all at the same temperature (the inside and outside of the PCV are atmospheric temperature), so V6 = V7 and Vt = V0, but the reactor is operating, If a temperature difference occurs inside and outside the PCV, V6
Since ≠ V7, Vt ≠ V0, and the indicator / recorder 3
The indicated value is different.

That is, if there are even mistakes in the connection polarities and they are all at the same temperature, the mistakes will not appear in the indicator / recorder 3, but if they are odd, the mistakes will occur in the indicator / recorder 3. Appears on recorder 3.

Therefore, the present invention utilizes such a principle to detect the connection state as shown in FIG.

In the present invention, as a method of changing the temperature at the connection point, the connection point is irradiated with light from a light projector to heat the connection point.

Although there are various heating methods, the above-mentioned light irradiation method is effective as a method for surely heating without giving a thermal damage to a small gap or other device parts.

At this time, the connection point to be heated is the connection point 6
Alternatively, it is one of the connection points 7.

As a result, if the indicated value of the indicator / recorder 3 does not change even if the connected portion is heated, it can be confirmed that the connection is normally made as shown in FIG. If it changes, it can be determined that the connection is as shown in FIG.

In the above description, as a method for changing the temperature of the connection point, the connection point is irradiated with light from the light projector to heat the connection point. However, the present invention is not limited to this, and conversely, cooling is performed. The temperature of the connection point may be changed.

In this case, if a cooling spray is used, it is effective because it can be surely cooled without causing thermal damage to small gaps and other equipment parts, and it does not remain like water, so aftereffects of the test, etc. There is an advantage that does not occur.

[0047]

As described above, according to the thermocouple circuit test method of the present invention, by changing the temperature of the connection point constituting the thermocouple circuit, it becomes possible to detect a connection error in the thermocouple circuit test. , Improve the reliability of the test.

[Brief description of drawings]

FIG. 1 is a thermocouple circuit diagram with proper connections.

FIG. 2 is a wrongly connected thermocouple circuit diagram.

FIG. 3 is a diagram showing thermoelectromotive force in a thermocouple circuit that is correctly connected.

FIG. 4 is a diagram showing a thermoelectromotive force in a thermocouple circuit that is erroneously connected.

[Explanation of symbols]

1 PCV 2 thermocouple 3 Indicator / Recorder 4 cable penetration 5-7 (5a-7b) Connection points 8 (8a, 8b) Thermocouple side cable 9 (9a, 9b) conductor 10 (10a, 10b) Instrument side cable

Claims (6)

[Claims] 1. The thermocouple when the temperature of a thermocouple provided on one side through a wall such as a partition wall is input to an indicator or a recorder installed on the other side to measure the temperature. And a cable penetration embedded in the wall, and a thermocouple side cable connecting the thermocouple and the cable penetration, and a cable penetration embedded in the wall. A thermocouple circuit test method comprising a pair of the same kind of metal wires, and a connection test of a thermocouple circuit constituted by the cable penetration and an instrument side cable connecting the indicator or the recorder, wherein the thermocouple , Thermocouple side cables, cable penetrations, instrument side cables, and one connection point on the indicator or recorder to a temperature different from the other connection points, Than the change of the indicator or recorder of time,
A thermocouple circuit test method characterized by determining the suitability of these connection states. 2. The thermocouple, the thermocouple side cable, the cable penetration, the instrument side cable, and one connection point of the indicator or recorder are heated to a temperature different from the temperature of the other connection point, and at that time, 2. The thermocouple circuit test method according to claim 1, wherein the suitability of these connection states is judged from the change in the indicator or recorder. 3. The thermocouple, the thermocouple-side cable, the cable penetration, the instrument-side cable, and one connection point in the indicator or recorder are irradiated with light from a projector to heat the connection point, thereby 3. The thermocouple circuit test method according to claim 2, wherein the temperature is set to a temperature different from the temperature of other connection points, and the suitability of these connection states is determined from the change of the indicator or the recorder at that time. . 4. A thermocouple, a thermocouple-side cable, a cable penetration, an instrument-side cable, and one connection point of the indicator or recorder are cooled to a temperature different from the temperature of other connection points, and at that time 2. The thermocouple circuit test method according to claim 1, wherein the suitability of these connection states is judged from the change in the indicator or recorder. 5. The temperature of the thermocouple, the thermocouple-side cable, the cable penetration, the instrument-side cable, and one connection point in the indicator or recorder is sprayed with a cooling spray to cool the temperature of the connection point. 5. The thermocouple circuit test method according to claim 4, wherein the temperature of the other connection points is set to a temperature different from that of the other connection points, and the suitability of these connection states is determined from the change of the indicator or the recorder at that time. 6. The thermocouple circuit testing method according to claim 1, wherein the wall is a partition wall of a reactor containment vessel.