JPH0658820A - Thermocouple measuring apparatus - Google Patents
Thermocouple measuring apparatusInfo
- Publication number
- JPH0658820A JPH0658820A JP4235334A JP23533492A JPH0658820A JP H0658820 A JPH0658820 A JP H0658820A JP 4235334 A JP4235334 A JP 4235334A JP 23533492 A JP23533492 A JP 23533492A JP H0658820 A JPH0658820 A JP H0658820A
- Authority
- JP
- Japan
- Prior art keywords
- thermocouple
- deterioration
- output
- resistance
- amplifying means
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Measuring Temperature Or Quantity Of Heat (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】この発明は、記録計等の計器に用
いられる熱電対測定装置に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermocouple measuring device used for measuring instruments such as recorders.
【０００２】[0002]
【従来の技術】熱電対を用いて温度を測定する場合、熱
電対を高温雰囲気で使用していると劣化して抵抗値が増
大する等して熱起電力値に誤差を発生する。このため、
従来、実際に使用している熱電対と正しい熱電対とを差
し換えて、その測定値の違いから劣化を検出したり、あ
るいは、所定期間使用したときに自動的に交換するよう
にしていた。2. Description of the Related Art When a temperature is measured by using a thermocouple, when the thermocouple is used in a high temperature atmosphere, it deteriorates and its resistance value increases, so that an error occurs in the thermoelectromotive force value. For this reason,
Conventionally, the thermocouple actually used is replaced with the correct thermocouple, and deterioration is detected from the difference in the measured values, or the thermocouple is automatically replaced when used for a predetermined period.
【０００３】[0003]
【発明が解決しようとする課題】このため、熱電対の劣
化が通常は不明であり、差し換えたり、自動的な交換を
したりすると、費用が増大し、また、作業の手間も多く
必要とする問題点があった。For this reason, the deterioration of the thermocouple is usually unknown, and replacement or automatic replacement increases the cost and requires a lot of labor. There was a problem.
【０００４】この発明の目的は、以上の点に鑑み、常に
測定しながら熱電対の劣化が検知できるようにした熱電
対測定装置を提供することである。In view of the above points, an object of the present invention is to provide a thermocouple measuring device capable of detecting deterioration of the thermocouple while always measuring.
【０００５】[0005]
【課題を解決するための手段】この発明は、劣化により
抵抗値が変化する熱電対が接続される増幅手段とこの増
幅手段の入力ライン間に接続される比較用抵抗と、前記
増幅手段の出力の変化から前記熱電対の劣化を検出する
測定手段とを備えるようにした熱電対測定装置である。According to the present invention, there is provided an amplifying means to which a thermocouple whose resistance value changes due to deterioration is connected, a comparing resistor connected between input lines of the amplifying means, and an output of the amplifying means. And a measuring means for detecting the deterioration of the thermocouple from the change of the thermocouple.
【０００６】[0006]
【実施例】図１では、この発明の一実施例を示す構成説
明図である。DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a structural explanatory view showing an embodiment of the present invention.
【０００７】図において、１１、１２、…は、各々測温
箇所に設けられる熱電対で、入力端子ｔ１１、ｔ１２、
またはｔ２１、ｔ２２、…を介し切換スイッチＳ１１、
Ｓ１２、または、Ｓ２１、Ｓ２２、…で切換選択されて
増幅手段２に接続され、その出力はＡ−Ｄ変換器、μＣ
ＰＵ等を含む測定手段３で演算処理され図示しない記録
手段等に出力される。In the figure, reference numerals 11, 12, ... Are thermocouples respectively provided at the temperature measuring points, and input terminals t11, t12,
Alternatively, via t21, t22, ... Changeover switch S11,
S12, or S21, S22, ... Switched and selected and connected to the amplifying means 2, the output of which is an AD converter, .mu.C.
The calculation means 3 including the PU and the like performs arithmetic processing and outputs the result to a recording means or the like (not shown).
【０００８】どの熱電対についても同様なので、第１チ
ャンネルについて以下説明する。Since the same applies to all thermocouples, the first channel will be described below.
【０００９】熱電対１１は、劣化により変化する内部抵
抗ｒ１をもち、導線抵抗ｒ２（２線分を合算）を介し、
端子ｔ１１、ｔ１２、切換スイッチｓ１１、ｓ１２、入
力ラインＬ１、Ｌ２を経て高い入力抵抗ＲＬをもつ増幅
手段２に接続される。入力ラインＬ１、Ｌ２間には、低
抵抗の比較用抵抗ＲがスイッチＳｏと直列に接続されて
いる。このスイッチＳｏのオン、オフは測定手段３で制
御される。なお、このスイッチＳｏは省略することも可
能である。そして、熱電対１１の熱起電力をＥｉ、比較
抵抗Ｒについての電圧をＥｏとすると、以下の式が成り
立つ。なお増幅手段２の入力抵抗ＲＬは大きいので省略
した。The thermocouple 11 has an internal resistance r1 which changes due to deterioration, and through a conductor resistance r2 (total of two wires),
The terminals t11, t12, the changeover switches s11, s12, and the input lines L1, L2 are connected to the amplifying means 2 having a high input resistance RL. A low-resistance comparison resistor R is connected in series with the switch So between the input lines L1 and L2. The on / off of the switch So is controlled by the measuring means 3. The switch So can be omitted. Then, assuming that the thermoelectromotive force of the thermocouple 11 is Ei and the voltage of the comparative resistor R is Eo, the following formula is established. Since the input resistance RL of the amplification means 2 is large, it is omitted.
【００１０】まず、比較用抵抗Ｒを接続しないと、 Ｅｏ＝Ｅｉ （１） であり、比較用抵抗Ｒを接続した場合において、劣化し
ていない正常のときは、ｒ１＝０であるので、 Ｅｏ＝ＥｉＲ／（ｒ２＋Ｒ） （２） 劣化するとｒ１が発生するので、 Ｅｏ＝Ｅｉ・Ｒ／（ｒ１＋ｒ２＋Ｒ） （３） となる。First, when the comparison resistor R is not connected, Eo = Ei (1), and when the comparison resistor R is connected and r1 = 0 in a normal state without deterioration, Eo = EiR / (r2 + R) (2) Since r1 is generated when deteriorated, Eo = Ei · R / (r1 + r2 + R) (3)
【００１１】この（２）式と（３）式の電圧が増幅手段
２の出力となるから、この増幅手段２の出力の変化から
熱電対１１のの劣化を測定手段３で検出することができ
る。Since the voltages of the equations (2) and (3) become the output of the amplifying means 2, the deterioration of the thermocouple 11 can be detected by the measuring means 3 from the change of the output of the amplifying means 2. .
【００１２】ここで、図２の出力比較説明図を参照する
と、Ｅｉ＝１０００℃（あるいはＡ−Ｄ変換後で１００
０カウントを考えてもよい）、Ｒ＝１ＫΩ、ｒ１＝１０
Ω、ｒ２＝１０Ωのとして、通常、比較用抵抗Ｒを接続
しないときは、出力Ｅｏ＝Ｅｉ＝１０００であるが、比
較抵抗Ｒを接続すると正常時で９９０．１となり、劣化
時で９８０．４となり、この変化、差に基き、一定値と
比較して劣化を検出するようにすればよい。Referring to the output comparison explanatory view of FIG. 2, Ei = 1000 ° C. (or 100 after A-D conversion)
0 count may be considered), R = 1 KΩ, r1 = 10
Assuming that Ω and r2 = 10Ω, the output Eo = Ei = 1000 when the comparison resistor R is not connected, but when the comparison resistor R is connected, the output becomes 990.1 in a normal state and 980.4 in a deteriorated state. Therefore, based on this change and difference, the deterioration may be detected by comparing with a fixed value.
【００１３】つまり、スイッチＳｏがないか常時オンの
比較用抵抗Ｒを接続した状態では、出力が９９０．１か
ら９８０．４に変化するのを見れば良く、スイッチＳｏ
をオン、オフするのであれば、出力１０００のところ、
９９０．１であるべきであるのに９８０．４に変化した
点を検出すればよい。これらは適当な偏差警報の設定値
を設けて劣化を報知するようにする。That is, it is sufficient to see that the output changes from 990.1 to 980.4 in the state where the switch So is not provided or the comparison resistor R which is always on is connected.
If you want to turn on and off, at output 1000,
It suffices to detect a point that should have been 990.1 but has changed to 980.4. For these, an appropriate deviation alarm set value is provided to notify deterioration.
【００１４】次に、（２）、（３）式を見て分るよう
に、比較用抵抗Ｒを接続すると、導線抵抗ｒ２の影響を
受け正しい測定データが得られない。この影響を除去す
るためのスケーリング補正演算を施すとよい。熱電対が
正常時は、補正係数Ｂとし、 Ｅｏ＝Ｅｉ・［Ｒ／（ｒ２＋Ｒ）］・Ｂ ＝Ｅｉ・［Ｒ／（ｒ２＋Ｒ）］・［（ｒ２＋Ｒ）／Ｒ］ ＝Ｅｉ （４） となり、劣化して内部抵抗ｒ１が発生すると、 Ｅｏ＝Ｅｉ・［Ｒ／（ｒ１＋ｒ２＋Ｒ）］・［（ｒ２＋Ｒ／Ｒ）］ （５） となる。この（４）式と（５）式の電圧が増幅手段２の
出力となるから、この出力変化から測定手段３で熱電対
の劣化を検知することができる。Next, as can be seen from the equations (2) and (3), when the comparison resistor R is connected, correct measurement data cannot be obtained due to the influence of the conductor wire resistance r2. It is advisable to perform a scaling correction calculation to remove this effect. When the thermocouple is normal, the correction coefficient is set to B, and Eo = Ei. [R / (r2 + R)]. B = Ei. [R / (r2 + R)]. [(R2 + R) / R] = Ei (4) When the internal resistance r1 is generated due to deterioration, Eo = Ei. [R / (r1 + r2 + R)]. [(R2 + R / R)] (5). Since the voltages of the equations (4) and (5) become the output of the amplifying means 2, the measuring means 3 can detect the deterioration of the thermocouple from the change in the output.
【００１５】ここで、図２の出力比較説明図を参照する
と、スケーリングした場合、スイッチＳｏがないか常時
オンの比較抵抗Ｒを接続した状態でも、配線抵抗ｒ２の
影響なく正常時１０００と常に正しい値を示し、劣化時
は９９０．２となり、この変化を利用して熱電対の劣化
をより正確に検出できる。なお、（２）式と（３）式の
差についてスケーリング補正を演算して用いるようにし
てもよい。Here, referring to the output comparison explanatory view of FIG. 2, in the case of scaling, even when the switch So is absent or the always-on comparison resistor R is connected, the wiring resistance r2 is not affected and the normal state is always 1000. It shows a value and becomes 990.2 at the time of deterioration, and the deterioration of the thermocouple can be detected more accurately by utilizing this change. The scaling correction may be calculated and used for the difference between the expressions (2) and (3).
【００１６】ところで、熱電対が劣化すると、測定デー
タが変化し、真値より低い起電力となるので、スケーリ
ング補正後の出力等に対し、抵抗値変化の影響を除去す
るリニアライズ補正演算を行い測定時に正しい出力が得
られるようにするとよい。When the thermocouple deteriorates, the measured data changes and the electromotive force is lower than the true value. Therefore, the linearized correction calculation for removing the influence of the resistance value change is performed on the output after scaling correction. It is advisable to obtain the correct output during measurement.
【００１７】以上、１チャンネルにつき説明したが、こ
れは他の各チャンネルについても同様で、多点記録計等
の計器に用いることができる。Although one channel has been described above, the same applies to each of the other channels, and it can be used for instruments such as a multipoint recorder.
【００１８】[0018]
【発明の効果】以上述べたように、この発明は、増幅手
段の入力ライン間に比較用抵抗を接続し、その出力変化
から熱電対の劣化を検知しているので、常に測定しなが
ら熱電対の劣化を検知できる。また、配線抵抗の影響を
除去するスケーリング補正演算を施すことにより常時正
しいデータとの比較ができ、記録計、その他の用途に好
適である。As described above, according to the present invention, since the resistance for comparison is connected between the input lines of the amplifying means and the deterioration of the thermocouple is detected from the output change, the thermocouple is constantly measured. Deterioration can be detected. Further, by performing a scaling correction calculation that removes the influence of wiring resistance, it is possible to always compare with correct data, which is suitable for recorders and other applications.
【図１】この発明の一実施例を示す構成説明図である。FIG. 1 is a structural explanatory view showing an embodiment of the present invention.
【図２】この発明の出力比較説明図である。FIG. 2 is an output comparison explanatory view of the present invention.
１１、１２ 熱電対 ２ 増幅手段 ３ 測定手段 ｒ１ 熱電対の抵抗 ｒ２ 配線抵抗 Ｒ 比較用抵抗 ＲＬ 入力抵抗 Ｓｏ スイッチ Ｓ１１、Ｓ１２、Ｓ２１、Ｓ２２ 切換スイッチ Ｌ１、Ｌ２ 入力ライン ｔ１１、ｔ１２、ｔ２１、ｔ２２ 端子 11, 12 Thermocouple 2 Amplifying means 3 Measuring means r1 Thermocouple resistance r2 Wiring resistance R Comparison resistance RL Input resistance So switch S11, S12, S21, S22 Changeover switch L1, L2 Input line t11, t12, t21, t22 Terminal
Claims (4)
される増幅手段と、この増幅手段の入力ライン間に接続
される比較用抵抗と、前記増幅手段の出力の変化から前
記熱電対の劣化を検出する測定手段とを備えた熱電対測
定装置。1. A amplifying means to which a thermocouple whose resistance value changes due to deterioration is connected, a comparison resistor connected between input lines of the amplifying means, and a change in the output of the amplifying means from the thermocouple. A thermocouple measuring device comprising a measuring means for detecting deterioration.
ときと接続されないときについての増幅手段の出力変化
またはその差に基いて熱電対の劣化を検知する測定手段
を備えた請求項１記載の熱電対測定装置。2. A measuring means for detecting deterioration of a thermocouple based on a change in the output of the amplifying means or a difference between when the resistance for comparison is connected to the input line and when it is not connected. Thermocouple measuring device.
とき前記増幅手段の出力から前記入力ラインの配線抵抗
の影響を除去するスケーリング補正演算を行う測定手段
を備えた請求項１または請求項２記載の熱電対測定装
置。3. A measuring means for carrying out a scaling correction operation for removing the influence of the wiring resistance of the input line from the output of the amplifying means when the comparison resistor is connected to the input line. The thermocouple measuring device described in 2.
とき前記増幅手段のスケーリング補正演算出力から前記
熱電対の劣化による抵抗値変化の影響を除去するリニア
ライズ補正演算を行う請求項１または請求項２または請
求項３記載の熱電対測定装置。4. A linearization correction calculation for removing an influence of a resistance value change due to deterioration of the thermocouple from a scaling correction calculation output of the amplification means when the comparison resistor is connected to an input line. The thermocouple measuring device according to claim 2 or 3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4235334A JPH0658820A (en) | 1992-08-11 | 1992-08-11 | Thermocouple measuring apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4235334A JPH0658820A (en) | 1992-08-11 | 1992-08-11 | Thermocouple measuring apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0658820A true JPH0658820A (en) | 1994-03-04 |
Family
ID=16984570
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4235334A Pending JPH0658820A (en) | 1992-08-11 | 1992-08-11 | Thermocouple measuring apparatus |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0658820A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0845645A (en) * | 1995-08-10 | 1996-02-16 | Nippondenso Co Ltd | Spark gap generating method for spark plug having noble metal contact |
| US6592418B2 (en) | 2001-02-08 | 2003-07-15 | Ngk Spark Plug Co., Ltd. | Method for manufacturing spark plug and apparatus for carrying out the same |
-
1992
- 1992-08-11 JP JP4235334A patent/JPH0658820A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0845645A (en) * | 1995-08-10 | 1996-02-16 | Nippondenso Co Ltd | Spark gap generating method for spark plug having noble metal contact |
| US6592418B2 (en) | 2001-02-08 | 2003-07-15 | Ngk Spark Plug Co., Ltd. | Method for manufacturing spark plug and apparatus for carrying out the same |
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