JPH01158370A - Method for measuring dc component of power cable - Google Patents
Method for measuring dc component of power cableInfo
- Publication number
- JPH01158370A JPH01158370A JP31631087A JP31631087A JPH01158370A JP H01158370 A JPH01158370 A JP H01158370A JP 31631087 A JP31631087 A JP 31631087A JP 31631087 A JP31631087 A JP 31631087A JP H01158370 A JPH01158370 A JP H01158370A
- Authority
- JP
- Japan
- Prior art keywords
- cable
- conductor
- component
- measured
- shield layer
- 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.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims abstract description 8
- 239000004020 conductor Substances 0.000 claims abstract description 21
- 230000007935 neutral effect Effects 0.000 claims abstract description 18
- 239000003990 capacitor Substances 0.000 claims description 6
- 238000009413 insulation Methods 0.000 description 5
- 238000005259 measurement Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 235000006650 Syzygium cordatum Nutrition 0.000 description 1
- 240000005572 Syzygium cordatum Species 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
Abstract
Description
【発明の詳細な説明】
〔技術分野〕
本発明は、電力ケーブルの絶縁性能の診断を活線下で行
うため、電力ケーブルの導体と遮蔽層間に流れる電流の
直流成分を測定する方法に関するものである。[Detailed Description of the Invention] [Technical Field] The present invention relates to a method for measuring the direct current component of a current flowing between a conductor and a shielding layer of a power cable in order to diagnose the insulation performance of the power cable under live wire conditions. be.
活線下にある電力ケーブルの導体と遮蔽層間に流れる電
流つまり絶縁層を通うて流れる電流の直流成分の大きさ
は、絶縁層の劣化と密接な関係があることが知られてい
る。従ってこの直流成分を測定すれば、ＣＶケーブルの
絶縁層に発生する水トリーなどを検出することが可能で
ある。It is known that the magnitude of the DC component of the current flowing between the conductor of a power cable under a live line and the shielding layer, that is, the current flowing through the insulating layer, is closely related to the deterioration of the insulating layer. Therefore, by measuring this DC component, it is possible to detect water trees generated in the insulation layer of the CV cable.
従来、この直流成分の測定は図−２のようにして行われ
ている。電力ケーブルｌは導体２の外周に絶縁層（図示
せず）を介して遮蔽層３を設けた構造で、導体２は高圧
母線４に接続されて活線状態にある。また高圧母線４に
はＧＰＴ （接地型計器用変圧器）５が接続され、その
中性点が接地されている０通常の運転状態では遮蔽層３
の両端は接地されているが、直流成分を測定するときは
、遮蔽層３の一端と大地の間に交流接地用コンデンサ６
と直流電流測定袋Ｗ７との並列回路を接続し、他端の接
地を開放する。これにより遮蔽層３は、直流的には大地
と絶縁され、交流的には低インビ−ダンス接地された状
態となる。Conventionally, the measurement of this DC component has been carried out as shown in Figure 2. The power cable 1 has a structure in which a shielding layer 3 is provided on the outer periphery of a conductor 2 via an insulating layer (not shown), and the conductor 2 is connected to a high voltage bus 4 and is in a live state. In addition, a GPT (grounded potential transformer) 5 is connected to the high voltage bus 4, and its neutral point is grounded.In normal operating conditions, the shielding layer 3
is grounded at both ends, but when measuring DC components, connect an AC grounding capacitor 6 between one end of the shielding layer 3 and the ground.
Connect the parallel circuit between the DC current measuring bag W7 and the DC current measuring bag W7, and open the grounding at the other end. As a result, the shielding layer 3 is insulated from the ground in terms of direct current and grounded with low impedance in terms of alternating current.
このようにすると直流成分は、高圧充電部から電力ケー
ブルの導体２−同絶縁層一同遮蔽層３−直流電流測定装
置７−大地−ＧＰＴ５→高圧充電部という経路で一点鎖
線矢印のように流れることになる。したがって直流電流
測定装置７の値を読めば、電力ケーブルの絶縁層に流れ
る電流の直流成分が測定できるわけである。In this way, the DC component will flow from the high-voltage live part to the conductor 2 of the power cable - the same insulating layer and the shielding layer 3 - the DC current measuring device 7 - the ground - GPT5 -> the high-voltage live part as shown by the dashed-dotted line arrow. become. Therefore, by reading the value of the DC current measuring device 7, the DC component of the current flowing through the insulation layer of the power cable can be measured.
なお高圧母線４が接地変圧器あるいは中性点接地型変圧
器に接続されている場合は、ＧＰＴ５の代わりに、その
変圧器の中性点接地部を利用することもある。Note that when the high voltage bus 4 is connected to a grounding transformer or a neutral point grounding type transformer, the neutral point grounding section of the transformer may be used instead of the GPT 5.
ところが同じＧＰＴ５に図示のように他の電力ケーブル
１１が接続されている場合には、その電力ケーブル１１
の導体１２と遮蔽層１３間に流れる電流の直流成分が点
線矢印のように流れ、直流電流測定装置７の測定値に影
響を及ぼすことになる。However, if another power cable 11 is connected to the same GPT 5 as shown in the figure, that power cable 11
The DC component of the current flowing between the conductor 12 and the shielding layer 13 flows as indicated by the dotted arrow, and influences the measured value of the DC current measuring device 7.
このように複数本の電力ケーブルが、中性点が接地され
た一つの変圧器と接続されている場合には、測定対象ケ
ーブルについての直流成分の測定値に誤差が生じ、絶縁
性能の診断を誤るおそれがある。In this way, when multiple power cables are connected to a single transformer whose neutral point is grounded, errors occur in the measured value of the DC component of the cable being measured, making it difficult to diagnose the insulation performance. There is a risk of making a mistake.
本発明の目的は、上記のような従来技術の問題点に鑑み
、複数本の電力ケーブルが、中性点が接地された変圧器
（ＧＰＴ、接地変圧器、中性点接地型変圧器など）と接
続されている場合に、そのうちの１本の電力ケーブルに
ついて、導体と遮蔽層間に流れる電流の直流成分の測定
を精度よ（行う方法を提供することにある。In view of the problems of the prior art as described above, an object of the present invention is to connect multiple power cables to a transformer whose neutral point is grounded (GPT, grounding transformer, neutral point grounding type transformer, etc.). The object of the present invention is to provide a method for accurately measuring the direct current component of the current flowing between the conductor and the shielding layer for one of the power cables when the conductor and the shielding layer are connected to the conductor.
この目的を達成するため本発明は、複数本の電力ケーブ
ルが接続された上記変圧器の中性点と大地の間に、交流
接地用コンデンサと直流電流測定装置との並列回路を接
続すると共に、測定対象ケーブルの遮蔽層を上記並列回
路の大地側に接続し、かつ非測定対象ケーブルの遮蔽層
を上記変圧器の中性点に接続し、その状態で上記直流電
流測定装置に流れる直流電流を測定することを特徴とす
るものである。In order to achieve this object, the present invention connects a parallel circuit of an AC grounding capacitor and a DC current measuring device between the neutral point of the transformer to which a plurality of power cables are connected and the earth, and The shielding layer of the cable to be measured is connected to the ground side of the parallel circuit, and the shielding layer of the cable not to be measured is connected to the neutral point of the transformer, and in this state, the DC current flowing through the DC current measuring device is It is characterized by measurement.
このようにすると非測定対象ケーブルの直流成分が直流
電流測定装置に流れ込まなくなり、測定対象ケーブルの
みについて直流成分の測定を正確に行うことが可能とな
る。In this way, the DC component of the cable not to be measured will not flow into the DC current measuring device, and it will be possible to accurately measure the DC component of only the cable to be measured.
以下、本発明の一実施例を図−１を参照して詳細に説明
する。Hereinafter, one embodiment of the present invention will be described in detail with reference to FIG.
図−１において図−２と同一部分には同一符号を付しで
ある。この測定方法が従来と異なる点は、交流接地用コ
ンデンサ６と直流電流測定装置７との並列回路を、ＧＰ
Ｔ５の中性点と大地の間に接続すると共に、測定対象ケ
ーブルｌの遮蔽層３を上記並列回路の大地側に電線８に
より接続し、かつ非測定対象ケーブル１１の遮蔽層１３
をＧＰＴ５の中性点に電線９により接続した状態で、測
定を行うことである。In FIG. 1, the same parts as in FIG. 2 are given the same reference numerals. The difference between this measurement method and the conventional method is that the parallel circuit of the AC grounding capacitor 6 and the DC current measuring device 7 is
T5 is connected between the neutral point and the ground, and the shielding layer 3 of the cable to be measured l is connected to the ground side of the parallel circuit by an electric wire 8, and the shielding layer 13 of the cable not to be measured 11 is connected to the ground side of the cable to be measured.
The measurement is performed while the GPT 5 is connected to the neutral point of the GPT 5 by an electric wire 9.
このようにすると測定対象ケーブル１の導体２と遮蔽層
３間に流れる電流は一点鎖線矢印のように流れ、その直
流成分は直流電流測定装置７に流れるが、非測定対象ケ
ーブル１１の４体１２と遮蔽層１３間に流れる電流は点
線矢印のように流れ、直流電流測定装置７には流れなく
なる。したがって直流電流測定装置７では、測定対象ケ
ーブルｌの導体２と遮蔽層３間に流れる電流の直流成分
だけを正確に測定できることになる。In this way, the current flowing between the conductor 2 and the shielding layer 3 of the cable 1 to be measured flows as indicated by the dashed-dotted line arrow, and its DC component flows to the DC current measuring device 7, but the 4 members 12 of the cable 11 not to be measured flow. The current flowing between the shielding layer 13 and the shielding layer 13 flows as indicated by the dotted arrow, and no longer flows to the DC current measuring device 7. Therefore, the DC current measuring device 7 can accurately measure only the DC component of the current flowing between the conductor 2 and the shielding layer 3 of the cable l to be measured.
上記実施例では、非測定対象ケーブルの遮蔽層とＧＰＴ
の中性点とを電線で直接接続したが、この間を女波接地
用コンデンサ６と同様の直流カット用フィルタを介して
接続しても同様の効果が得られる。In the above embodiment, the shielding layer of the cable not to be measured and the GPT
Although the neutral point of is directly connected with an electric wire, the same effect can be obtained by connecting this through a DC cut filter similar to the female wave grounding capacitor 6.
また上記実施例では非測定対象ケーブルを１本だけ示し
たが、同じＧＰＴに非測定対象ケーブルが複数本接続さ
れている場合も同様である。Further, in the above embodiment, only one cable not to be measured is shown, but the same applies when a plurality of cables not to be measured are connected to the same GPT.
〔発明の効果〕
以上説明したように本発明によれば、複数本の電力ケー
ブルが中性点が接地された変圧器と接続されていて、そ
のうちの１本の電力ケーブルについて導体と遮蔽層間に
流れる電流の直流成分の測定を行う場合に、非測定対象
ケーブルの導体と遮蔽層間に流れる電流の影響を受ける
ことなく、測定対象ケーブルの導体と遮蔽層間に流れる
電流の直流成分だけを測定することができるから、測定
精度が向上し、絶縁性能診断の信頼性を高めることがで
きる。[Effects of the Invention] As explained above, according to the present invention, a plurality of power cables are connected to a transformer whose neutral point is grounded, and for one of the power cables, there is a gap between the conductor and the shielding layer. To measure only the DC component of the current flowing between the conductor of the cable to be measured and the shielding layer without being affected by the current flowing between the conductor of the cable to be measured and the shielding layer when measuring the DC component of the flowing current. This improves measurement accuracy and increases the reliability of insulation performance diagnosis.
図−１は本発明の一実施例に係る電力ケーブルの直流成
分測定方法を示す回路図、図−２は従来の測定方法を示
す回路図である。
ｌ：測定対象ケーブル、２：導体、３：遮蔽層、４：高
圧母線、５二ＧＰＴ、６：交流接地用コンデンサ、７：
直流電流測定装置、８・９：電線、１１：非測定対象ケ
ーブル、１２＝導体、１３ Ｆ ＩＩ）ｆ。FIG. 1 is a circuit diagram showing a method for measuring a direct current component of a power cable according to an embodiment of the present invention, and FIG. 2 is a circuit diagram showing a conventional measuring method. l: Cable to be measured, 2: Conductor, 3: Shielding layer, 4: High voltage bus, 52 GPT, 6: AC grounding capacitor, 7:
DC current measuring device, 8/9: Electric wire, 11: Cable not to be measured, 12 = Conductor, 13 F II) f.
Claims (1)
続されており、そのうちの１本の電力ケーブルにつき、
導体と遮蔽層間に流れる電流の直流成分を測定する方法
において、上記変圧器の中性点と大地の間に、交流接地
用コンデンサと直流電流測定装置との並列回路を接続す
ると共に、測定対象ケーブルの遮蔽層を上記並列回路の
大地側に接続し、かつ非測定対象ケーブルの遮蔽層を上
記変圧器の中性点に接続し、その状態で上記直流電流測
定装置に流れる直流電流を測定することを特徴とする電
力ケーブルの直流成分測定方法。Multiple power cables are connected to a transformer whose neutral point is grounded, and for each power cable,
In a method of measuring the DC component of a current flowing between a conductor and a shielding layer, a parallel circuit consisting of an AC grounding capacitor and a DC current measuring device is connected between the neutral point of the transformer and the earth, and the cable to be measured is connecting the shielding layer of the above-mentioned parallel circuit to the ground side, and connecting the shielding layer of the cable not to be measured to the neutral point of the above-mentioned transformer, and measuring the DC current flowing through the above-mentioned DC current measuring device in this state. A method for measuring DC components of power cables, characterized by:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62316310A JPH077028B2 (en) | 1987-12-16 | 1987-12-16 | Method for measuring DC component of power cable |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62316310A JPH077028B2 (en) | 1987-12-16 | 1987-12-16 | Method for measuring DC component of power cable |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01158370A true JPH01158370A (en) | 1989-06-21 |
| JPH077028B2 JPH077028B2 (en) | 1995-01-30 |
Family
ID=18075706
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62316310A Expired - Lifetime JPH077028B2 (en) | 1987-12-16 | 1987-12-16 | Method for measuring DC component of power cable |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH077028B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015064627A1 (en) | 2013-10-31 | 2015-05-07 | 三菱瓦斯化学株式会社 | Xylylenediamine composition and method for producing polyamide resin |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60262069A (en) * | 1984-06-11 | 1985-12-25 | Furukawa Electric Co Ltd:The | Monitoring of deterioration in insulation of power cable |
-
1987
- 1987-12-16 JP JP62316310A patent/JPH077028B2/en not_active Expired - Lifetime
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60262069A (en) * | 1984-06-11 | 1985-12-25 | Furukawa Electric Co Ltd:The | Monitoring of deterioration in insulation of power cable |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015064627A1 (en) | 2013-10-31 | 2015-05-07 | 三菱瓦斯化学株式会社 | Xylylenediamine composition and method for producing polyamide resin |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH077028B2 (en) | 1995-01-30 |
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