JP6210564B2 - Power cable connection protective tube and partial discharge measuring device - Google Patents

Description

The present invention relates to a connection portion protection tube and a partial discharge measuring device in a connection portion of a power cable.

In a power cable, if there are voids, foreign matter, etc. in the insulator, partial discharge may occur during energization, which may eventually lead to dielectric breakdown.
Conventionally, a pair of metal foil electrodes are attached to the outer peripheries of the anticorrosion layers on both sides of the insulation tube at the connection part of the power cable with the metal sheath being cut across the insulation tube, and the detection impedance is connected to these electrodes Was.
If a partial discharge occurs in the insulator when a current is passed through the power cable, a change occurs in the charge of the metal foil electrode on one side, so that the detection impedance connected to the pair of metal foil electrodes Thus, the occurrence of partial discharge was detected by the measuring device (see, for example, Patent Documents 1 and 2).

JP 2003-2448027 A Japanese Patent No. 3033667

However, in the above-described prior art, when measuring the partial discharge for the connection portion of the existing power cable, the work of attaching the metal foil electrode to the surface of the anticorrosion layer of the connection portion is performed. The area of the metal foil used varies depending on the size of the connection part, and it is difficult to attach the metal foil to the surface of the anticorrosion layer of the power cable connection part without any gaps. There was a problem that occurred.
In particular, metal foil installation work is subject to differences in installation conditions, such as the presence or absence of gaps, depending on the level of skill of the operator, and variations in capacitance are likely to occur. Standardization of work and capacitance detection values It was desired to stabilize.

In addition, the metal foil is peeled off from the connection portion of the power cable after the measurement, but is easily deformed or damaged at the time of peeling, and it is almost difficult to reuse. It was not preferable from the viewpoint of resources.
In addition, installation work for partial discharge measurement is performed in a narrow environment such as in a cave or manhole, and there are many obstacles that hinder the work of cable support hardware etc. at the installation site. The work required time and the work efficiency was poor, and the work burden was heavy.

  An object of the present invention is to suppress the variation in the capacitance to be detected and to detect a good partial discharge.

The invention according to claim 1 is a connection protective tube for a power cable.
A metal tube arranged on the outer periphery of the connecting portion of the power cable ;
An anticorrosion layer covering the metal tube,
A pair of the metal tubes are provided on both sides of the insulating cylinder, and each of the metal tubes is provided with a connection terminal for calibration and a connection terminal for measurement as the connection terminal for partial discharge detection.
An opening for exposing the connection terminal to the outside is provided in the anticorrosion layer,
An openable / closable lid that shields the connection terminal from the outside is provided in the opening,
The connection terminal for measurement and the connection terminal for calibration are arranged on the same side with respect to the central axis on the circumference of the cross section perpendicular to the central axis of the metal tube,
The opening exposes both the connection terminal for measurement and the connection terminal for calibration to the outside,
The lid shields both the connection terminal for measurement and the connection terminal for calibration from the outside .

Invention of Claim 2 is a partial discharge measuring apparatus provided with the connection part protection tube of the electric power cable of Claim 1, and the detection component for partial discharge measurement connected to the connection terminal of the connection part protection tube,
The detection component for partial discharge measurement includes a lead wire connecting the connection terminal to an impedance detection element, and a capacitor interposed in the middle of the lead wire.

  The present invention includes a metal tube disposed on the outer periphery of the connection portion of the power cable, and the metal tube has a connection terminal for detecting partial discharge. Thus, it is possible to easily connect the capacitor, and it is unnecessary to provide a metal foil electrode outside the metal tube. Therefore, like metal foil, the area does not vary depending on the size of the connecting portion of the power cable, and the occurrence of non-uniform gaps can be avoided, so that variation in capacitance caused by these can be suppressed, It is possible to improve the accuracy of detection results by standardizing work and stabilizing the capacitance value.

In addition, since a disposable metal foil electrode is not required, generation of waste can be suppressed, the environment can be protected, and resource saving can be achieved.
In addition, it eliminates the need for metal foil installation work and enables measurement by attaching lead wires and capacitors to the electrodes. Therefore, obstruction factors such as cable support hardware in narrow environments such as in caves and manholes, etc. Even in an environment with a large amount of work, the work can be performed easily and quickly, and the work load can be reduced.

It is a front view of the connection part protection pipe | tube of the power cable which is embodiment of invention. It is sectional drawing along the VV line of FIG. It is a perspective view which shows the state by which only the copper pipe was equipped in the insulating layer of the intermediate connection part except the anti-corrosion layer. It is a block diagram which shows schematic structure of a partial discharge measuring apparatus. It is sectional drawing of the detection component for partial discharge measurement. It is sectional drawing of the connection part protective tube which shows the connection state of the detection component for partial discharge measurements. It is an equivalent circuit diagram of the intermediate connection part of a power cable, and a connection part protective tube. It is a perspective view which shows the other example of a connection terminal. It is a perspective view which shows the other example of a connection terminal. It is a perspective view which shows the other example of a connection terminal.

[Outline of Embodiments of the Invention]
An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a front view of a connecting portion protection tube 10 of a power cable according to the present embodiment, and FIG. 2 is a cross-sectional view taken along line VV in FIG.
The connection portion protection tube 10 is provided in an intermediate connection portion 110 as a connection portion of the power cable 100 and has a structure suitable for detection of partial discharge of the power cable 100 performed by the partial discharge measurement device 40.

In the power cable 100, a conductor 101, an insulating layer, a shielding layer (not shown), and an anticorrosion layer are mainly formed in order from the inside.
And the intermediate connection part 110 which connects the power cable 100 and the power cable 100, as shown in FIG.1 and FIG.2, the conductor connection part which does not illustrate the conductors 101 of the two power cables 100, and its A reinforcing insulating layer 102 formed in the periphery, and an insulating cylinder 103 that is provided on the outer periphery of the reinforcing insulating layer 102 and insulates the shielding layers of the two power cables 100 are provided. A connection protection tube 10 is provided.

[Protection tube for connection part]
The connection portion protection tube 10 includes a copper tube 20 as a pair of metal tubes that covers the outer periphery of the reinforcing insulating layer 102 on both sides of the insulating tube 103, and an anticorrosion layer 30 that covers the entire surface of each copper tube 20. I have.

FIG. 3 illustrates a state where the anticorrosion layer 30 of the connection portion protection tube 10 is removed.
As illustrated, the reinforcing insulating layer 102 of the intermediate connection portion 110 of the power cable 100 has a cylindrical shape along the longitudinal direction of the cable, and both end portions thereof have a conical shape with a gradually reduced diameter. An annular insulating cylinder 103 is formed at the center of the outer periphery of the reinforcing insulating layer 102.

The two copper tubes 20 of the connection portion protection tube 10 are individually provided on the outer peripheral surface of the reinforcing insulating layer 102 on both sides of the insulating cylinder 103. These copper tubes 20 have a shape corresponding to the external shape of the reinforcing insulating layer 102.
That is, each copper tube 20 is an internal hollow tube that penetrates the entire length, one end of which is a conical shape that gradually decreases in diameter like the reinforcing insulating layer 102, and the other end has a constant inner diameter and outer diameter. It is formed in a cylindrical shape.
With this shape, each copper tube 20 is attached to the reinforcing insulating layer 102 with its inner surface facing the outer peripheral surface of the reinforcing insulating layer 102.
The copper tube 20 as a metal tube is not limited to copper, and may be a good conductor.

Each copper tube 20 is erected in a state where two connection terminals 21 and 22 for partial discharge detection are close to each other on the outer peripheral surface thereof.
Each of the connection terminals 21 and 22 has a square bridge shape, and a through hole is formed in the lower part thereof.
These connection terminals 21 and 22 are made of copper, and are integrally formed on the surface of the copper tube 20.
These connection terminals 21 and 22 are used for partial discharge detection in the power cable 100. One connection terminal 21 is a connection terminal for measurement, and the other connection terminal 22 is a connection terminal for calibration. The details of the use of these connection terminals 21 and 22 will be described later.

  The anticorrosion layer 30 covers the entire outer peripheral surface of the copper tube 20 and protects the copper tube 20 from corrosion. The anticorrosion layer 30 is preferably an insulating material, and for example, vinyl chloride resin is used.

The anticorrosion layer 30 has a circular opening 31 so as not to cover the connection terminals 21 and 22 of the copper tube 20, and the connection terminals 21 and 22 are exposed.
The periphery of the opening 31 is raised in a cylindrical shape, and a circular lid 32 is mounted from above the opening 31. The lid 32 is detachable. When the lid 32 is removed, the connection terminals 21 and 22 inside the opening 31 are exposed, and a detection component 50 for measuring partial discharge described later can be connected from the outside.

A sealing material (for example, an O-ring) that seals the gap between the lid 32 and the opening 31 in a watertight and airtight manner is provided. Further, a screw structure may be provided between the lid 32 and the opening 31 so that the lid 32 can be detached by rotating the lid 32.
The inner diameter of the lid 32 is substantially the same as the outer diameter of the opening 31, and the opening 31 is closed by inserting the cylindrical opening 31 into the lid 32. It is good also as a structure which inserts the lid | cover 32 and obstruct | occludes the opening part 31. FIG.

[Partial discharge measuring device]
FIG. 4 is a block diagram showing a schematic configuration of the partial discharge measuring apparatus 40.
The partial discharge measuring device 40 detects the partial discharge of the power cable by using the connection portion protection tube 10 as an electrode.
That is, the partial discharge measurement device 40 includes an impedance detection element 41 connected to a measurement connection terminal 21 provided on a pair of copper tubes 20 of the connection portion protection tube 10 via a partial discharge measurement detection component 50; A measuring device 42 for measuring a potential difference between both ends of the impedance detection element 41 to detect a partial discharge detection signal, and a pulse generator 43 connected to a calibration connection terminal 22 provided in a pair of copper tubes 20 are provided. ing. In FIG. 4, the connection terminals 21 and 22 are not shown.

FIG. 5 is a cross-sectional view of a partial discharge measurement detection component 50 for connecting the measurement connection terminal 21 to the impedance detection element 41, and FIG.
The detection component 50 for partial discharge measurement includes a lead wire 51 that electrically connects the connection terminal 21 for detection and the impedance detection element 41, a capacitor 52 interposed in the middle of the lead wire 51, and the lead wire 51. A conductive clip 53 provided at one end and capable of gripping the connection terminal 21 and a protective case 54 for storing the capacitor 52 are provided.

The protective case 54 is a case made of an insulating material, for example, plastic, and the inside is sealed so as to prevent moisture from entering.
As shown in FIG. 6, the clip 53 holds the connection terminal 21 and is electrically connected to the lead wire 51.
The type of the capacitor 52 is not limited, but a capacitor whose capacitance is known (for example, about 1000 pF) is used.
The connection terminal 22 and the pulse generator 43 are connected by a partial discharge measurement detection component that excludes the capacitor 52 and the case 54.

FIG. 7 is an equivalent circuit of the intermediate connection portion 110 of the power cable and the copper tube 20 of the connection portion protection tube 10.
Since the two power cables 100 are both insulated between the conductor 101 and the copper tube 20, when electricity flows through the conductor 101, charges can be stored between the conductor 101 and the copper tube 20. That is, as shown in the drawing, the conductor 101 of each cable 100, each of the pair of copper tubes 20, and the insulating region therebetween can be regarded as capacitors having electrostatic capacitances C1 and C2.
7 is a capacitor 52 of the detection component 50 for partial discharge measurement connected to the connection terminal 21 of each copper tube 20 (capacitances C3 and C4 have the same value). Is).

For example, when a void or the like exists in the insulating layer of one power cable 100 (on the right side in FIG. 7), when the voltage is higher than a certain value when the voltage is applied to the power cable 100, the void is periodically removed from the void. Partial discharge P occurs, and a discharge pulse is generated. When the discharge pulse is generated, the partial discharge measurement device 40 detects a potential difference at both ends of the impedance detection element 41 connected to the copper tube 20, and this is detected by the measurement device 42.
As the impedance detection element 41, for example, a resistance element or the like is used.

[Partial discharge measurement work]
The connection portion protection tube 10 is manufactured in a state where the copper tube 20, the anticorrosion layer 30, the connection terminals 21 and 22, the opening portion 31, and the lid 32 are integrated in advance in a factory. And each copper pipe 20 of this connection part protection pipe | tube 10 is attached to each outer periphery of the two electric power cables 100 which make a connection at the time of formation of the intermediate connection part 110. FIG.

When performing the partial discharge measurement operation on the power cable 100, as shown in FIGS. The internal connection terminals 21 and 22 are exposed.
Next, the connection terminals 21 on both sides are sandwiched between the clips 53 of the detection component 50 for partial discharge measurement, and these connection terminals 21 are connected to one end of the impedance detection element 41 of the partial discharge measurement device 40 and the other through the capacitor 52. Connect individually to the end.
Similarly, the connection terminals 22 on both sides are connected to the pulse generator 43 via the detection components for partial discharge measurement.
And the presence or absence of generation | occurrence | production of the discharge pulse intrinsic | native to partial discharge is measured by the measuring apparatus 42 of the partial discharge measuring apparatus 40. FIG.
After measuring whether or not the discharge pulse is generated, the partial discharge measurement detection component 50 connected to the connection terminal 21 and the partial discharge measurement detection component connected to the connection terminal 22 are removed.
Further, a lid 32 is attached to each opening 31, and the inside of the opening 31 is sealed to complete the measurement operation.

[Technical effect of protective pipe for connection part]
The connection portion protection tube 10 includes a pair of copper tubes 20 disposed on the outer periphery of the intermediate connection portion 110 of the power cable, and each copper tube 20 is exposed to the outside of the anticorrosion layer 30 and is used for partial discharge detection. Therefore, when the partial discharge of the power cable 100 is measured, the capacitor 52 is easily attached to the copper tube 20, and the metal foil electrode can be dispensed with. Therefore, unlike the metal foil, the area does not vary depending on the size of the intermediate connection portion 110 of the power cable, and the occurrence of uneven gaps can be avoided, so that variation in capacitance due to these can be suppressed. It is possible to improve the accuracy of the detection result by standardizing the work and stabilizing the capacitance value.
Further, since no metal foil is required, it is possible to suppress the generation of waste, protect the environment, and save resources.

  Furthermore, the installation work of the metal foil is not required, and the measurement can be performed by attaching the detection component 50 for partial discharge measurement composed of the lead wire 51 and the capacitor 52 to each connection terminal 21, 22. It is possible to work easily and quickly even in a small environment such as the inside or an environment where there are many obstacle factors such as cable support hardware, and it is possible to reduce the work load. Become.

  Moreover, since each copper pipe 20 of the connection part protection pipe 10 is provided with the connection terminal 22 for calibration and the connection terminal 21 for measurement, the installation work of the metal foil for calibration is unnecessary, and calibration. The work can be easily performed, and the accuracy of the detection result can be improved while reducing the work load.

In addition, each anticorrosion layer 30 of the connection portion protection tube 10 includes an openable / closable lid 32 that shields the connection terminal from the outside, so that the connection terminals 21 and 22 are exposed to the outside by opening the lid 32 during measurement. The connection terminals 21 and 22 can be sealed and protected from the outside during non-measurement. Therefore, it is possible to enhance the durability of the connection terminals 21 and 22 while ensuring the ease of the partial discharge measurement operation.
Furthermore, since each lid 32 is provided in the cylindrical opening 31, the attachment structure of the lid 32 can be simplified, and the connection portion protection tube 10 can be easily manufactured.

  Further, since the pair of copper tubes 20 are arranged on both sides of the connection tube 10 with the insulating tube 103 interposed therebetween, partial discharge can be detected from the potential difference between the pair of copper tubes 20.

  In addition, since the partial discharge measurement detection component 50 that connects the connection terminal 21 of the connection protection tube 10 to the impedance detection element 41 includes a capacitor 52 having a known capacitance in the middle of the lead wire 51, it looks like a metal foil. In addition, the capacitance value does not become unstable, and the measurement accuracy can be improved.

[Others]
The connection terminals 21 and 22 provided on the copper tube 20 are not limited to a rectangular bridge shape as long as the detection component 50 for partial discharge measurement can be connected.
As shown in FIG. 8, a round bar pin-shaped connection terminal 21 </ b> B may be provided on the copper tube 20. Even in the case of a bridge shape, the shape is not limited to a rectangle, and a triangular loop connection terminal 21C shown in FIG. 9 and a semi-ellipse loop connection terminal 21D shown in FIG. . Further, the connection terminal 22 may have the same shape as the connection terminals 21B to 21D.

10 Connection protection tube 20 Copper tube (metal tube)
21 Connection terminal for measurement 22 Connection terminal for calibration 30 Corrosion protection layer 31 Opening 32 Cover 40 Partial discharge measuring device 41 Impedance detection element 50 Detection component for partial discharge measurement 51 Lead wire 52 Capacitor 100 Power cable 103 Insulating cylinder 110 Intermediate connection Part (connection part)

Claims (2)

A metal tube arranged on the outer periphery of the connecting portion of the power cable ;
An anticorrosion layer covering the metal tube,
A pair of the metal tubes are provided on both sides of the insulating cylinder, and each of the metal tubes is provided with a connection terminal for calibration and a connection terminal for measurement as a connection terminal for partial discharge detection.
An opening for exposing the connection terminal to the outside is provided in the anticorrosion layer,
An openable / closable lid that shields the connection terminal from the outside is provided in the opening,
The connection terminal for measurement and the connection terminal for calibration are arranged on the same side with respect to the central axis on the circumference of a cross section perpendicular to the central axis of the metal tube,
The opening exposes both the connection terminal for measurement and the connection terminal for calibration to the outside,
The lid covers the connection terminal for measurement and the connection terminal for calibration from the outside . Includes a connecting portion protection tube power cable; and a partial discharge measurement detection components connected to the connection terminals of the connection portion protection tube in claim 1,
The partial discharge measurement detection component, a lead wire for connecting the connection terminals to the impedance detection device, partial discharge measuring device, characterized in that it comprises a capacitor interposed in the middle of the lead wire.

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