JPH0236191B2 - - Google Patents
Info
- Publication number
- JPH0236191B2 JPH0236191B2 JP57042790A JP4279082A JPH0236191B2 JP H0236191 B2 JPH0236191 B2 JP H0236191B2 JP 57042790 A JP57042790 A JP 57042790A JP 4279082 A JP4279082 A JP 4279082A JP H0236191 B2 JPH0236191 B2 JP H0236191B2
- Authority
- JP
- Japan
- Prior art keywords
- cable
- charge
- amount
- absorbed
- discharge
- 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.)
- Expired - Lifetime
Links
- 208000028659 discharge Diseases 0.000 claims description 20
- 239000004020 conductor Substances 0.000 claims description 15
- 240000005572 Syzygium cordatum Species 0.000 claims description 11
- 235000006650 Syzygium cordatum Nutrition 0.000 claims description 11
- 238000009413 insulation Methods 0.000 claims description 9
- 238000005259 measurement Methods 0.000 claims description 8
- 238000001514 detection method Methods 0.000 claims description 6
- 230000005611 electricity Effects 0.000 claims 2
- 230000006866 deterioration Effects 0.000 description 7
- 238000000034 method Methods 0.000 description 5
- 239000003990 capacitor Substances 0.000 description 3
- 239000004698 Polyethylene Substances 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- -1 polyethylene Polymers 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- 229920003020 cross-linked polyethylene Polymers 0.000 description 1
- 239000004703 cross-linked polyethylene Substances 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1227—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials
- G01R31/1263—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation
- G01R31/1272—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation of cable, line or wire insulation, e.g. using partial discharge measurements
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Electric Cable Installation (AREA)
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
- Testing Relating To Insulation (AREA)
Description
【発明の詳細な説明】
本発明は、ポリエチレンケーブルに多く発生す
る水トリーの有無を検出する検出方法に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a detection method for detecting the presence or absence of water trees, which often occur in polyethylene cables.
水トリーは、ケーブルにおいて絶縁体に浸透し
てくる水分と、絶縁体中のボイド、半導電層の突
起等の異常電界部が原因で発生し、ケーブルの絶
縁特性を著しく劣化せしめる原因となるものであ
る。 Water treeing is caused by moisture that permeates into the insulation of a cable, as well as abnormal electric field areas such as voids in the insulation and protrusions in the semiconducting layer, and causes a significant deterioration of the insulation properties of the cable. It is.
最近は、この水トリーによつてポリエチレン絶
縁ケーブルの破壊事故が頻発し、大きな問題とな
つてきている。 Recently, this water tree has caused frequent destruction of polyethylene insulated cables, and this has become a major problem.
そこで、本発明者等は上記の問題を解決する方
法として、ケーブルの放電特性から水トリーの発
生の有無を検出する方法を提案した。（特願昭50
−115341号）。具体的には直流電源で測定しよう
とするケーブルを充電し、しかる後放電せしめ、
この放電電流を約30秒間測定して積分することに
より吸収電荷量Ｑを求めこの値を比較することに
より劣化を判定しようとするものである。 Therefore, the present inventors proposed a method of detecting the occurrence of water trees from the discharge characteristics of the cable as a method for solving the above problem. (Special request 1977
−115341). Specifically, the cable to be measured is charged with a DC power source, and then discharged.
By measuring and integrating this discharge current for about 30 seconds, the amount of absorbed charge Q is determined, and by comparing this value, deterioration is determined.
しかし、この方法では測定しようとするケーブ
ルが実布設の長尺なケーブルの場合には、ケーブ
ル自身の容量Ｃが大きいため、充放電時の電荷量
Ｑが大きくなり、水トリー発生部の余効電流（時
間的遅れのある電流）がマスクされてしまい検出
できないという欠点があつた。 However, with this method, if the cable to be measured is a long cable actually installed, the cable itself has a large capacitance C, so the amount of charge Q during charging and discharging will be large, and the aftereffects of the water tree generation part will be The drawback was that the current (current with a time delay) was masked and could not be detected.
そこで放電初期の瞬間放電電流をバイパスさせ
た後、所定時間の遅れをもつて継続して放電する
余効電流の放電電流を測定して吸収電荷量を求め
ることを特徴とする水トリーの検出方法が提案さ
れた。（特願昭52−21779号）
しかしながら実際の測定にあたつては、ケーブ
ルは地中に埋設されているためその終端のヘツド
部を通して行なうことになるのでケーブル自体の
放電特性を測定するに際し、ヘツド部が同時に測
定されることになるためケーブル部分の劣化判定
はきわめて困難であつた。 Therefore, a method for detecting water trees is characterized in that after bypassing the instantaneous discharge current at the initial stage of discharge, the discharge current of the aftereffect current that continues to be discharged with a delay of a predetermined time is measured to determine the amount of absorbed charge. was proposed. (Japanese Patent Application No. 52-21779) However, since the cable is buried underground, the actual measurement must be made through the head at the end of the cable, so when measuring the discharge characteristics of the cable itself, Since the head section was measured at the same time, it was extremely difficult to judge the deterioration of the cable section.
即ち、ヘツド部にはコンパウンドが充填されて
いるため劣化による吸収電荷量の増加はケーブル
部に比べてはるかに大きく充放電時の電荷量を大
きくするからである。 That is, since the head portion is filled with compound, the increase in the amount of absorbed charge due to deterioration is much greater than that in the cable portion, increasing the amount of charge during charging and discharging.
以上の欠点に鑑み本発明は、ケーブルヘツドか
ら測定しても、ヘツド部の影響は受けずにケーブ
ル部のみの劣化の判定ができるようにした水トリ
ーの検出方法を提供するもので、その要旨とする
ところは、導体上に絶縁層、遮蔽層、シースを設
けたケーブルを地中に埋設し、その端部に前記遮
蔽層と離間して接地されたヘツドが接続されたケ
ーブルをケーブルヘツドから充電し、しかる後放
電し、放電初期の瞬間放電電流をバイパスさせ、
その後所定時間の遅れをもつて余効電流の放電電
流を吸収電荷量として測定し、その吸収電荷量か
ら水トリーの有無を検出する検出方法において、
最初にケーブル遮蔽層を接地した後、所定時間課
電し、その後導体を短絡して放電することによつ
て、ヘツド部の吸収電荷量Q1およびケーブル絶
縁層の吸収電荷量Q2を測定し、次にケーブル遮
蔽層と導体を接続した後、同様にして所定時間課
電し、その後ケーブル遮蔽層を接地するとともに
導体を短絡して放電することにより、ケーブルヘ
ツドの吸収電荷量Q1を測定し、第１の測定によ
る上記吸収電荷量Q1＋Q2と第２の測定による吸
収電荷量Q1との差からケーブル絶縁層の吸収電
荷量Q2を求めて水トリーの検出を行なうことを
特徴とするものである。 In view of the above-mentioned drawbacks, the present invention provides a method for detecting water trees in which deterioration of only the cable section can be determined without being affected by the head section even when measuring from the cable head. In this case, a cable with an insulating layer, a shielding layer, and a sheath provided on the conductor is buried underground, and a cable with a grounded head separated from the shielding layer is connected to the end of the cable from the cable head. Charge and then discharge, bypassing the instantaneous discharge current at the initial stage of discharge,
In the detection method, the discharge current of the aftereffect current is then measured as the amount of absorbed charge after a delay of a predetermined time, and the presence or absence of water trees is detected from the amount of absorbed charge.
After first grounding the cable shielding layer, a voltage is applied for a predetermined period of time, and then the conductor is short-circuited and discharged to measure the amount of charge absorbed by the head section Q1 and the amount of charge absorbed by the cable insulation layer Q2 . Next, after connecting the cable shielding layer and the conductor, a voltage is applied in the same way for a predetermined time, and then the cable shielding layer is grounded and the conductor is short-circuited to discharge, thereby measuring the amount of charge Q 1 absorbed by the cable head. Then, the amount of absorbed charge Q 2 of the cable insulation layer is determined from the difference between the amount of absorbed charge Q 1 + Q 2 obtained by the first measurement and the amount of absorbed charge Q 1 obtained by the second measurement, and the water tree is detected. This is a characteristic feature.
以下、本発明を図面により詳細に説明する。 Hereinafter, the present invention will be explained in detail with reference to the drawings.
第１図は電力ケーブルの電荷量の検出回路を示
したもので、１は測定しようとするケーブルを示
し、１ａはその導体、１ｂはその架橋ポリエチレ
ン絶縁層、１ｃはその遮蔽層、１ｄはそのシース
で、このケーブル１は地中２に埋設されている。
３はケーブルヘツドでケーブル端部が挿入される
とともに金属ケース３ａは接地されている。 Figure 1 shows a circuit for detecting the amount of charge in a power cable. 1 indicates the cable to be measured, 1a is its conductor, 1b is its crosslinked polyethylene insulation layer, 1c is its shielding layer, and 1d is its With a sheath, this cable 1 is buried underground 2.
3 is a cable head into which the end of the cable is inserted, and the metal case 3a is grounded.
３ｂはケース内部に充填されたコンパウンドで
ある。４は直流電源、５は電流測定器、例えばピ
コアンメーターで７はこの電流を時間で積分した
電荷量として測定するための電荷量測定器であ
る。 3b is a compound filled inside the case. Reference numeral 4 denotes a DC power supply, 5 a current measuring device such as a picoammeter, and 7 a charge amount measuring device for measuring the amount of charge integrated with time.
S1は直流電源４の切換スイツチ、例えば真空ス
イツチ、S2は放電電流測定用の切換スイツチ、S3
は電流測定器５に並列に接続されたバイパス回路
のバイパススイツチで、タイマー６によつて作動
する。これらの切換スイツチS1，S2，S3は相互に
連動し、切換スイツチS1が入つた時切換スイツチ
S2が開き、また切換スイツチS1が開いた時、切換
スイツチS2，S3が入る。 S 1 is a changeover switch for the DC power supply 4, for example a vacuum switch, S 2 is a changeover switch for measuring discharge current, S 3
is a bypass switch of a bypass circuit connected in parallel to the current measuring device 5, and is activated by a timer 6. These changeover switches S 1 , S 2 , and S 3 are interlocked with each other, and when changeover switch S 1 is turned on, the changeover switch
When S 2 is opened and changeover switch S 1 is also opened, changeover switches S 2 and S 3 are turned on.
またスイツチS3はタイマー６により一定時間後
切れるよう作動する。 Further, the switch S3 is operated by a timer 6 so as to be turned off after a certain period of time.
切換スイツチS4は遮蔽層１を接地し、又は導体
１ａに接続するための切換スイツチである。 The changeover switch S4 is a changeover switch for grounding the shielding layer 1 or connecting it to the conductor 1a.
しかして実線路の測定回路を第２図乃至第５図
の要部等価回路に代えて示す。 Therefore, a measurement circuit for an actual line is shown in place of the main equivalent circuits in FIGS. 2 to 5.
図中、電荷量Q1は導体１ａとヘツド３間の容
量C1に、電荷量Q2は導体１ａと遮蔽層１ｃ間の
容量C2に、電荷量Q3は遮蔽層１ｃと地中２間の
容量C3にそれぞれ蓄えられる吸収電荷量を示す。 In the figure, the amount of charge Q 1 is added to the capacitance C 1 between the conductor 1a and the head 3, the amount of charge Q 2 is added to the capacitance C 2 between the conductor 1a and the shielding layer 1c, and the amount of charge Q 3 is added to the capacitance C 1 between the conductor 1a and the shielding layer 1c. It shows the amount of absorbed charge stored in the capacitance C3 between the two.
先ず第２図の如く切換スイツチS1を入れてケー
ブル遮蔽層１ｃを接地した後、切換スイツチS4の
可動接片ａを固定接点ｂ側に入れ直流電源４によ
つてたとえば２分間ヘツド容量C1、ケーブルの
容量C2をそれぞれ充電する。 First, as shown in Fig. 2, turn on the changeover switch S1 to ground the cable shielding layer 1c, then put the movable contact a of the changeover switch S4 to the fixed contact b side and set the head capacity C for 2 minutes using the DC power supply 4. 1 , charging cable capacity C 2 respectively.
この結果、容量C1，C2にはQ1およびQ2の電荷
が蓄えられる。 As a result, the charges of Q 1 and Q 2 are stored in the capacitors C 1 and C 2 .
次に第３図に示す如く切換スイツチS1を開きス
イツチS2を入れると、測定器５を介してC1／C2
〜１ａ〜S2の放電回路を形成してC1，C2に充電
された電荷Q1，Q2が放電される。 Next, as shown in FIG. 3, when the selector switch S 1 is opened and the switch S 2 is turned on, C 1 /C 2
A discharge circuit of ~1a~ S2 is formed, and the charges Q1 and Q2 charged in C1 and C2 are discharged.
実際には第１図に示すように初期の瞬間放電電
流が流れる期間（約３秒）はバイパススイツチS3
が入つているため電流は測定器には流れず、タイ
マー６が作動してスイツチS3が開いた後時間的に
遅れのある余効電流が電流測定器５により約30秒
測定され、電荷量測定器７に記録される。この測
定値Ｑは吸収電荷量Q1，Q2が加算されたものが
得られる。 In reality, as shown in Figure 1, during the initial instantaneous discharge current flow period (approximately 3 seconds), the bypass switch S3
is inserted, so no current flows to the measuring device, and after the timer 6 operates and switch S3 opens, the aftereffect current with a time delay is measured by the current measuring device 5 for about 30 seconds, and the amount of charge is measured. It is recorded on the measuring device 7. This measured value Q is obtained by adding the absorbed charge amounts Q 1 and Q 2 .
次に第４図の如く切換スイツチS4の可動接片ａ
を固定接点Ｃ側に入れて遮蔽層と導体１ａを接続
した後、切換スイツチS1を入れて直流電源４によ
つて容量C1，C3を２分間充電し電荷量Q1，Q3を
蓄える。この場合、容量C2の両端は同電位であ
るためC2への充電電荷量Q2は０である。 Next, as shown in Fig. 4, the movable contact piece a of the changeover switch S4
After connecting the shielding layer and the conductor 1a by putting them on the fixed contact C side, turn on the changeover switch S 1 and charge the capacitors C 1 and C 3 for 2 minutes with the DC power supply 4 to obtain the electric charges Q 1 and Q 3 . store. In this case, since both ends of the capacitor C 2 are at the same potential, the amount of charge Q 2 charged to C 2 is zero.
こうして、充分充電した後、第５図に示す如く
切換スイツチS1を開き切換スイツチS4の可動接片
ａを固定接点ｂ側に入れると、容量C3が短絡さ
れて電荷量Q3が０となる。したがつて電流測定
器５には電荷量Q1が測定される。 After being sufficiently charged in this way, when the changeover switch S1 is opened and the movable contact a of the changeover switch S4 is placed on the fixed contact b side as shown in FIG. 5, the capacitance C3 is short-circuited and the amount of charge Q3 becomes zero. becomes. Therefore, the electric charge amount Q 1 is measured by the current measuring device 5.
従つて、前記電荷量Ｑ（Q1＋Q2）と上記測定で
得られた電荷量Q1との差からケーブル絶縁層の
吸収電荷量Q2が求められる。 Therefore, the amount of charge Q 2 absorbed by the cable insulating layer is determined from the difference between the amount of charge Q (Q 1 +Q 2 ) and the amount of charge Q 1 obtained in the above measurement.
以上のように本発明によればケーブルヘツドが
接続された電力ケーブルのケーブル部分の劣化の
測定をケーブルヘツドの劣化の影響を受けること
なく行なうことができる。又測定はケーブルヘツ
ドから行なうことができるのでその作業は容易で
ある。 As described above, according to the present invention, it is possible to measure the deterioration of the cable portion of the power cable to which the cable head is connected without being affected by the deterioration of the cable head. Also, since measurements can be made from the cable head, the work is easy.
図面は本発明の実施例を示し、第１図はその検
出回路の一例を、第２図乃至第５図はその要部等
価回路に代えた検出順序を示す。
１……ケーブル、１ａ……導体、１ｂ……絶縁
層、１ｃ……遮蔽層、１ｄ……シース、２……地
中、３……ヘツド、４……直流電源、５……電流
測定器、６……タイマー、S1，S2，S3，S4……切
換スイツチ。
The drawings show an embodiment of the present invention, with FIG. 1 showing an example of its detection circuit, and FIGS. 2 to 5 showing equivalent circuits of its essential parts and alternative detection orders. 1... Cable, 1a... Conductor, 1b... Insulating layer, 1c... Shielding layer, 1d... Sheath, 2... Underground, 3... Head, 4... DC power supply, 5... Current measuring device , 6...timer, S1 , S2 , S3 , S4 ...changeover switch.
Claims (1)
ーブルを地中に埋設し、その端部に前記遮蔽層と
離間して接地されたヘツドが接続されたケーブル
をケーブルヘツドから充電し、しかる後放電し、
放電初期の瞬間放電電流をバイパスさせ、その後
所定時間の遅れをもつて余効電流の放電電流を吸
収電荷量として測定し、その吸収電荷量から水ト
リーの有無を検出する検出方法において、最初
に、ケーブル遮蔽層を接地した後、所定時間課電
し、その後導体を短絡して放電することによつて
ケーブルヘツドの吸収電荷量Q1と、ケーブル絶
縁層の吸収電荷量Q2を測定し、次にケーブル遮
蔽層と導体を接続した後、同様にして所定時間課
電し、その後ケーブル遮蔽層を接地するとともに
導体を短絡して放電することによりケーブルヘツ
ドの吸収電荷量Q1を測定し、上記第１の測定に
よる吸収電荷量Q1＋Q2と第２の測定による吸収
電荷量Q1との差からケーブル絶縁層の吸収電荷
量Q2を求めて水トリーの検出を行なうことを特
徴とする電力ケーブル絶縁層の水トリー検出方
法。1. A cable with an insulating layer, a shielding layer, and a sheath provided on the conductor is buried underground, and the cable, which has a grounded head separated from the shielding layer at the end, is charged from the cable head, and then After discharge,
In the detection method, the instantaneous discharge current at the initial stage of discharge is bypassed, and then after a predetermined delay, the discharge current of the aftereffect current is measured as the amount of absorbed charge, and the presence or absence of water tree is detected from the amount of absorbed charge. , after grounding the cable shielding layer, apply electricity for a predetermined time, then short-circuit the conductor and discharge to measure the amount of charge absorbed by the cable head Q1 and the amount of charge absorbed by the cable insulation layer Q2 , Next, after connecting the cable shielding layer and the conductor, electricity is similarly applied for a predetermined time, and then the cable shielding layer is grounded and the conductor is short-circuited to discharge, thereby measuring the amount of charge Q 1 absorbed by the cable head. The water tree is detected by determining the amount of absorbed charge Q 2 of the cable insulation layer from the difference between the amount of absorbed charge Q 1 +Q 2 obtained by the first measurement and the amount of absorbed charge Q 1 obtained by the second measurement. Water tree detection method for power cable insulation layer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57042790A JPS58161870A (en) | 1982-03-19 | 1982-03-19 | Detection of water tree for power cable insulation layer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57042790A JPS58161870A (en) | 1982-03-19 | 1982-03-19 | Detection of water tree for power cable insulation layer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS58161870A JPS58161870A (en) | 1983-09-26 |
| JPH0236191B2 true JPH0236191B2 (en) | 1990-08-15 |
Family
ID=12645753
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP57042790A Granted JPS58161870A (en) | 1982-03-19 | 1982-03-19 | Detection of water tree for power cable insulation layer |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS58161870A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3908585A1 (en) | 1989-03-16 | 1990-09-27 | Pi Patente Gmbh | VACUUM PACKING HOSE MADE OF A WELDABLE MATERIAL |
| EP3425411B1 (en) * | 2016-03-03 | 2023-03-22 | Sumitomo Electric Industries, Ltd. | Method for evaluating insulation properties of insulator |
| CN108445341B (en) * | 2018-03-01 | 2019-11-15 | 华南理工大学 | A Calculation Method for the Leakage Current of Each Section Under Multi-point Grounding of Cable Sheath |
-
1982
- 1982-03-19 JP JP57042790A patent/JPS58161870A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS58161870A (en) | 1983-09-26 |
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