JPH05256809A - Method for measuring potential to ground of object to be corrosion-prevented by external power method - Google Patents
Method for measuring potential to ground of object to be corrosion-prevented by external power methodInfo
- Publication number
- JPH05256809A JPH05256809A JP3067008A JP6700891A JPH05256809A JP H05256809 A JPH05256809 A JP H05256809A JP 3067008 A JP3067008 A JP 3067008A JP 6700891 A JP6700891 A JP 6700891A JP H05256809 A JPH05256809 A JP H05256809A
- Authority
- JP
- Japan
- Prior art keywords
- steel pipe
- soil
- voltage
- measured
- ground
- 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
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、地中埋設鋼管などの土
壌に埋設された被防食物体が外部電源法によって防食さ
れており、この被防食物体の対地電位を測定するための
方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the ground potential of a food item to be protected, which is buried in soil such as a steel pipe buried underground, by the external power source method.
【０００２】[0002]
【従来の技術】典型的な先行技術は、図３に示されてい
る。電気絶縁性の塗覆装を有する地中埋設鋼管１が外部
電源法によって防食されるために、直流電源２の負極が
接続され、この電源２の正極は、土壌に埋設されている
導体３に接続される。この鋼管１の電気防食効果が良好
に行なわれているかどうかを検出するために、電圧計４
が設けられ、この電圧計４の一端部（プラス側）は鋼管
１に接続され、他端部（マイナス側）は、土壌に接触さ
れているＣｕＳＯ4 照合電極５に接続される。電極防食
効果が良好に行われるには、この電圧計４によって測定
される鋼管１の分極電位が、−８５０ｍＶよりも卑であ
ることが好ましい。この鋼管１の分極電位をＶ１とし、
鋼管１にその鋼管１が塗覆装から露出している欠陥個所
６が存在することによって破線７で示されるように土壌
中を電流が流れて生じるいわゆるＩＲ降下電圧をＶ２と
するとき、電圧計４の測定電圧Ｖ３は数１で示される。2. Description of the Related Art A typical prior art is shown in FIG. Since the underground steel pipe 1 having an electrically insulating coating is protected by the external power source method, the negative electrode of the DC power source 2 is connected, and the positive electrode of this power source 2 is connected to the conductor 3 buried in the soil. Connected. In order to detect whether the anticorrosion effect of this steel pipe 1 is being performed well, a voltmeter 4
Is provided, one end (plus side) of the voltmeter 4 is connected to the steel pipe 1, and the other end (minus side) is connected to the CuSO 4 reference electrode 5 in contact with the soil. In order for the electrode anticorrosion effect to be excellent, it is preferable that the polarization potential of the steel pipe 1 measured by the voltmeter 4 is baser than −850 mV. The polarization potential of this steel pipe 1 is V1,
When the so-called IR drop voltage caused by the flow of current in the soil as indicated by the broken line 7 due to the presence of the defective portion 6 in which the steel pipe 1 is exposed from the coating is V2, a voltmeter The measured voltage V3 of No. 4 is shown by Formula 1.
【０００３】[0003]
【数１】Ｖ３＝Ｖ１＋Ｖ２ このＩＲ降下電圧Ｖ２は、欠陥個所６が存在するとき、
比較的大きな値であり、また欠陥個所６の大きさおよび
鋼管１が埋設されている土壌の性質などによって異な
る。したがって電圧計４の測定電圧Ｖ３だけからは、鋼
管１の分極電位Ｖ１を正確に測定することは不可能であ
る。## EQU1 ## V3 = V1 + V2 This IR drop voltage V2 is, when the defect portion 6 exists,
The value is relatively large, and varies depending on the size of the defective portion 6 and the nature of the soil in which the steel pipe 1 is buried. Therefore, it is impossible to accurately measure the polarization potential V1 of the steel pipe 1 only from the measured voltage V3 of the voltmeter 4.
【０００４】この問題を解決するために、従来ではま
た、直流電源２に直列にスイッチ８を介在し、このスイ
ッチ８を遮断した直後の時点における電圧計４の測定値
を読取ることによって、鋼管１に直流電源２によって防
食電流を流しているときにおける鋼管１の分極電位Ｖ１
を測定することができる。In order to solve this problem, conventionally, a switch 8 is also interposed in series with the DC power source 2, and the measured value of the voltmeter 4 immediately after the switch 8 is cut off is read to obtain the steel pipe 1. Polarization potential V1 of the steel pipe 1 when the anticorrosion current is applied by the DC power supply 2
Can be measured.
【０００５】図４は、この図３に示される先行技術の鋼
管１に関連する電位を示す図である。時刻ｔ１以前で
は、スイッチ８は導通され、時刻ｔ１以降では、スイッ
チ８は遮断される。鋼管１の自然電位Ｅｃｏｒｒは、鋼
管１に防食電流を流さないときにおける鋼管１の対地電
位である。ＯＮ電位Ｅｏｎは、スイッチ８が導通してい
るときにおける電圧計４の電圧を示し、ＯＦＦ電位Ｅｏ
ｆｆは、スイッチ８を遮断した直後の電圧計４の測定電
圧を示し、この時刻ｔ１におけるＯＦＦ電位Ｅｏｆｆを
知ることによって、鋼管１の分極電位Ｖ１を知ることが
でき、この対地電位Ｖ１が大きいほど、防食が良好に行
われていることになる。時刻ｔ１以降では、電圧計４の
測定電圧は、復極時間Ｗ１にわたって、時間とともに低
下してゆく。FIG. 4 is a diagram showing potentials associated with the steel pipe 1 of the prior art shown in FIG. The switch 8 is turned on before the time t1, and is turned off after the time t1. The natural potential Ecorr of the steel pipe 1 is the ground potential of the steel pipe 1 when no corrosion current is passed through the steel pipe 1. The ON potential Eon indicates the voltage of the voltmeter 4 when the switch 8 is conducting, and the OFF potential Eo
ff represents the measured voltage of the voltmeter 4 immediately after the switch 8 is cut off, and the polarization potential V1 of the steel pipe 1 can be known by knowing the OFF potential Eoff at this time t1, and the larger the ground potential V1 , The anti-corrosion is done well. After time t1, the voltage measured by the voltmeter 4 decreases with time over the depolarization time W1.
【０００６】[0006]
【発明が解決しようとする課題】このようなスイッチ８
を用いて、その遮断直後の電圧計４の電圧を測定する先
行技術では、そのスイッチ８を遮断した時刻ｔ１におけ
る電圧を測定する必要があるので、直流電源２と電圧計
４とがそれぞれ設けられている場所が長距離Ｌ１（図３
参照）、たとえば１０ｋｍにわたって、隔てられている
ときには、スイッチ８と同期して電圧計４による電圧の
測定を行うことが困難である。しかも電源２によって鋼
管１と導体３との間に流れる電流は、たとえば４０Ａで
あって大きな値であり、したがってスイッチ８の遮断時
には、電圧計４の測定値にノイズが含まれ、このことに
よってもまた、鋼管１の対地電位の測定値に誤差が含ま
れることになる。Such a switch 8
In the prior art in which the voltage of the voltmeter 4 immediately after the cutoff is measured by using, it is necessary to measure the voltage at the time t1 when the switch 8 is cut off. Therefore, the DC power supply 2 and the voltmeter 4 are provided respectively. The place where you are
Reference), for example, when it is separated by 10 km, it is difficult to measure the voltage by the voltmeter 4 in synchronization with the switch 8. Moreover, the current flowing between the steel pipe 1 and the conductor 3 by the power supply 2 is, for example, 40 A, which is a large value. Therefore, when the switch 8 is cut off, the measured value of the voltmeter 4 contains noise, which also causes Further, the measured value of the ground potential of the steel pipe 1 includes an error.
【０００７】本発明の目的は、地中埋設鋼管などの被防
食物体の対地電位を、高精度で測定することができるよ
うにした外部電源法による被防食物体の対地電位の測定
方法をを提供することである。An object of the present invention is to provide a method for measuring the ground potential of a food-protected object such as an underground steel pipe with high accuracy by means of an external power source method. It is to be.
【０００８】[0008]
【課題を解決するための手段】本発明は、土壌に埋設さ
れている被防食物体と土壌との間に、交流電源の全波整
流された電力を与え、被防食物体と土壌との間に流れる
電流が零となる時点における被防食物体と土壌に設けた
照合電極との間の電圧を測定することを特徴とする外部
電源法による被防食物体の対地電位測定方法である。The present invention provides a full-wave rectified electric power of an AC power source between a protected food body buried in soil and the soil, and between the protected food body and the soil. A method for measuring a ground potential of a food item to be protected by an external power source method, which comprises measuring a voltage between the food item to be protected and a reference electrode provided on the soil when the flowing current becomes zero.
【０００９】[0009]
【作用】本発明に従えば、被防食物体と土壌との間に
は、防食のために、または対地電位の測定のために、交
流電源の電力を全波整流して得られた電力が与えられ、
これによって被防食物体に防食電流が供給され、全波整
流して得られた電流が零の時点における被防食物体と土
壌に設けた照合電極、たとえばＣｕＳＯ4 照合電極との
間の電圧を測定する。この測定値は、被防食物体の対地
電位、したがって分極電位Ｖ１に対応しており、外部電
源法によって防食している状態における被防食物体の対
地電位を、ＩＲ降下電圧Ｖ２にかかわらず、正確に測定
することができるようになる。According to the present invention, the power obtained by full-wave rectifying the power of the AC power source is applied between the food-prevented body and the soil to prevent corrosion or to measure the ground potential. The
As a result, an anticorrosive current is supplied to the protected food, and the voltage between the protected food and the verification electrode provided on the soil, for example, CuSO 4 verification electrode, is measured when the current obtained by full-wave rectification is zero. .. This measured value corresponds to the ground potential of the protected food item, and therefore the polarization potential V1, and accurately measures the ground potential of the protected food object in the state of being protected by the external power source method regardless of the IR drop voltage V2. You will be able to measure.
【００１０】[0010]
【実施例】図１は、本発明の一実施例の全体の断面図で
ある。土壌１１には、電気絶縁性塗覆装を有する鋼管１
２が埋設されており、外部電源法によって電気防食が行
われる。この外部電源法による電気防食のために、商用
交流電源１３の電力は、トランス１４を経て、全波整流
回路１５によって全波整流され、その負極のライン１６
は鋼管１２に接続され、正極のライン１７は切換スイッ
チ１８の共通接点に接続される。全波整流回路１５は４
つのダイオードがブリッジ接続されて構成される。切換
スイッチ１８の一方の個別接点と切換スイッチ１９の一
方の個別接点とは、ライン２０を介して接続されてお
り、切換スイッチ１９の共通接点は、ライン２１を介し
て、土壌１１に埋設されている導体２２に接続される。
この導体２２は、たとえばフェライト、高硅素鉄、カー
ボン、および白金などであってもよい。切換スイッチ１
８，１９の他方の各個別接点間には、コンデンサ２３，
２４と抵抗２５とを含む平滑回路２６が設けられる。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of an embodiment of the present invention. On the soil 11, a steel pipe 1 having an electrically insulating coating
2 is buried, and cathodic protection is performed by the external power supply method. For the purpose of cathodic protection by the external power source method, the power of the commercial AC power source 13 is full-wave rectified by the full-wave rectifier circuit 15 via the transformer 14, and the negative line 16
Is connected to the steel pipe 12, and the positive line 17 is connected to the common contact of the changeover switch 18. The full-wave rectifier circuit 15 is 4
It consists of two diodes connected in a bridge. One individual contact of the changeover switch 18 and one individual contact of the changeover switch 19 are connected via a line 20, and the common contact of the changeover switch 19 is buried in the soil 11 via a line 21. Connected to the conductor 22.
The conductor 22 may be, for example, ferrite, high silicon iron, carbon, platinum, or the like. Changeover switch 1
Between the other individual contacts of 8 and 19, a capacitor 23,
A smoothing circuit 26 including 24 and a resistor 25 is provided.
【００１１】鋼管１２の電気防食のために、切換スイッ
チ１８，１９は図１に示されるスイッチング態様とさ
れ、全波整流回路１５からの出力は平滑回路２６によっ
て平滑されて、鋼管１２と導体２２との間に直流電力が
供給される。In order to prevent galvanic corrosion of the steel pipe 12, the changeover switches 18 and 19 are set to the switching mode shown in FIG. 1, and the output from the full-wave rectifier circuit 15 is smoothed by the smoothing circuit 26 to make the steel pipe 12 and the conductor 22. Direct current power is supplied between and.
【００１２】鋼管１２の対地電位を測定するためには、
切換スイッチ１８，１９は、ライン２０側に切換えられ
て接続される。この対地電位の測定のために、データロ
ガー（商品名）と呼ばれる電圧測定装置２７が用いら
れ、この電圧測定装置２７の一方の端子（プラス側）は
鋼管１２に接続され、他方の端子（マイナス側）はＣｕ
ＳＯ4 照合電極２８に接続される。この照合電極２８
は、土壌１１に接触される。電圧測定装置２７は、たと
えば１０μｓｅｃ毎に、鋼管１２と照合電極２８との間
の電圧をサンプリングして読取り、その測定結果を、内
部に備えられるメモリに順次的にストアする。In order to measure the ground potential of the steel pipe 12,
The changeover switches 18 and 19 are changed over to the line 20 side and connected. A voltage measuring device 27 called a data logger (trade name) is used for measuring the ground potential. One terminal (plus side) of the voltage measuring device 27 is connected to the steel pipe 12 and the other terminal (minus side). Side) is Cu
It is connected to the SO 4 reference electrode 28. This reference electrode 28
Is contacted with the soil 11. The voltage measuring device 27 samples and reads the voltage between the steel pipe 12 and the reference electrode 28, for example, every 10 μsec, and sequentially stores the measurement results in a memory provided therein.
【００１３】図２は、鋼管１２の対地電位測定時におい
て、ライン１６，２１から鋼管１２および導体２２に与
えられる全波整流電圧波形を示す。時刻ｔ１１，ｔ１２
では、その電圧は零であり、したがって鋼管１２と導体
２２との間、したがって土壌１１に流れる電流は零であ
る。商用交流電源１３がたとえば６０Ｈｚであるとき、
半周期Ｗ２は、８ｍｓｅｃである。電圧測定装置２７
は、鋼管１２と導体２２との間に図２に示される全波整
流された電圧が印加されて防食電流が供給されるとき、
その鋼管１２と照合電極２８との間の電圧を、上述のよ
うに１０μｓｅｃ毎にサンプリングして測定し、特に時
刻ｔ１１，ｔ１２付近における電圧を測定する。これに
よって鋼管１２と土壌１１との間に流れる電流が零であ
る時点ｔ１１，ｔ１２における鋼管１２と照合電極２８
との間の電圧を正確に測定することができ、この電圧
は、鋼管１２の分極電位Ｖ１（前述の図４参照）、した
がって対地電位Ｅｏｆｆに対応している。FIG. 2 shows a full-wave rectified voltage waveform applied to the steel pipe 12 and the conductor 22 from the lines 16 and 21 when measuring the ground potential of the steel pipe 12. Time t11, t12
Then, its voltage is zero, and therefore the current flowing between the steel pipe 12 and the conductor 22 and thus the soil 11 is zero. When the commercial AC power supply 13 is, for example, 60 Hz,
The half cycle W2 is 8 msec. Voltage measuring device 27
When the full-wave rectified voltage shown in FIG. 2 is applied between the steel pipe 12 and the conductor 22 to supply the anticorrosion current,
The voltage between the steel pipe 12 and the reference electrode 28 is sampled and measured every 10 μsec as described above, and the voltage is measured particularly near the times t11 and t12. As a result, the steel pipe 12 and the reference electrode 28 at times t11 and t12 when the current flowing between the steel pipe 12 and the soil 11 is zero.
The voltage between and can be accurately measured, which corresponds to the polarization potential V1 of the steel pipe 12 (see FIG. 4 above) and thus to the ground potential Eoff.
【００１４】電圧測定装置２７は、前述のように短時間
に電圧のサンプリングを行って測定する構成だけでな
く、その他の構成であってもよく、たとえばオシロスコ
ープなどを用いて電圧を測定するようにしてもよい。平
滑回路２６を省略し、全波整流回路１５の出力を、鋼管
１と導体２２との間に、常時与えるようにしてもよい。The voltage measuring device 27 is not limited to the configuration in which the voltage is sampled and measured in a short time as described above, but may have other configurations. For example, an oscilloscope or the like is used to measure the voltage. May be. The smoothing circuit 26 may be omitted, and the output of the full-wave rectification circuit 15 may be constantly applied between the steel pipe 1 and the conductor 22.
【００１５】地中埋設鋼管１２の他に、地中に埋設され
るその他の被防食物体に関連して本発明を広範囲に実施
することができる。In addition to the underground steel pipe 12, the present invention can be widely implemented in relation to other food-protected objects buried in the ground.
【００１６】[0016]
【発明の効果】以上のように本発明によれば、被防食物
体と土壌との間に、交流電源の全波整流された電力を与
えて、防食を行い、または対地電位の測定を行い、この
対地電位の測定は、全波整流された電流が零となる時点
における被防食物体と土壌に設けた照合電極との間の電
圧を測定して行われ、こうしてＩＲ降下電圧Ｖ２にかか
わらず、対地電位Ｖ１を高精度で測定することができ
る。As described above, according to the present invention, the full-wave rectified power of the AC power supply is applied between the food-prevention target and the soil to prevent corrosion or to measure the ground potential. The measurement of the ground potential is performed by measuring the voltage between the protected food and the reference electrode provided on the soil at the time when the full-wave rectified current becomes zero, and thus, regardless of the IR drop voltage V2, The ground potential V1 can be measured with high accuracy.
【図１】本発明の一実施例の全体の構成を示す図であ
る。FIG. 1 is a diagram showing the overall configuration of an embodiment of the present invention.
【図２】地中埋設鋼管１２の対地電位を測定するときに
地中埋設鋼管１２と導体２２とにライン１６，２１を介
して供給される全波整流されたされた電力の電圧波形を
示す図である。FIG. 2 shows voltage waveforms of full-wave rectified electric power supplied to the underground steel pipe 12 and the conductor 22 via lines 16 and 21 when measuring the ground potential of the underground steel pipe 12. It is a figure.
【図３】先行技術を示す図である。FIG. 3 is a diagram showing a prior art.
【図４】先行技術および本発明の一実施例の地中埋設鋼
管１，１２に関連する電位を説明するためのグラフであ
る。FIG. 4 is a graph for explaining potentials related to underground steel pipes 1 and 12 of the prior art and one embodiment of the present invention.
１１ 土壌 １２ 地中埋設鋼管 １３ 商用交流電源 １４ トランス １５ 全波整流回路 １８，１９ 切換スイッチ ２６ 平滑回路 ２７ 電圧測定装置 ２８ ＣｕＳＯ4 照合電極11 Soil 12 Underground Steel Pipe 13 Commercial AC Power Supply 14 Transformer 15 Full Wave Rectifier Circuit 18, 19 Changeover Switch 26 Smoothing Circuit 27 Voltage Measuring Device 28 CuSO 4 Reference Electrode
Claims (1)
との間に、交流電源の全波整流された電力を与え、 被防食物体と土壌との間に流れる電流が零となる時点に
おける被防食物体と土壌に設けた照合電極との間の電圧
を測定することを特徴とする外部電源法による被防食物
体の対地電位測定方法。1. A full-wave rectified electric power of an AC power source is applied between the food-subject to be protected buried in the soil and the soil, and a current flowing between the food-to-be-protected and the soil becomes zero. A method for measuring a ground potential of a food item to be protected by an external power source method, which comprises measuring a voltage between the food item to be protected and a reference electrode provided on soil.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3067008A JPH05256809A (en) | 1991-03-29 | 1991-03-29 | Method for measuring potential to ground of object to be corrosion-prevented by external power method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3067008A JPH05256809A (en) | 1991-03-29 | 1991-03-29 | Method for measuring potential to ground of object to be corrosion-prevented by external power method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05256809A true JPH05256809A (en) | 1993-10-08 |
Family
ID=13332467
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3067008A Pending JPH05256809A (en) | 1991-03-29 | 1991-03-29 | Method for measuring potential to ground of object to be corrosion-prevented by external power method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05256809A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06288958A (en) * | 1993-04-06 | 1994-10-18 | Tokyo Gas Co Ltd | Method for detecting corroded part of cast-iron pipe buried in ground |
| JP2003519725A (en) * | 1999-12-09 | 2003-06-24 | アプライド・セミコンダクター・インク | Method and system for preventing corrosion of conductive structures |
-
1991
- 1991-03-29 JP JP3067008A patent/JPH05256809A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06288958A (en) * | 1993-04-06 | 1994-10-18 | Tokyo Gas Co Ltd | Method for detecting corroded part of cast-iron pipe buried in ground |
| JP2003519725A (en) * | 1999-12-09 | 2003-06-24 | アプライド・セミコンダクター・インク | Method and system for preventing corrosion of conductive structures |
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