JP3397918B2 - Withstand voltage test method for power cable lines - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a withstand voltage test method for efficiently testing a power cable line directly connected to a sealed electric device.
Concerning the law .

[0002]

2. Description of the Related Art A power cable is subjected to a withstand voltage test on site after a new construction of a cable line, a system change work, or a trouble recovery work. In addition, the insulation performance of power cables gradually deteriorates during long-term use, which may lead to dielectric breakdown. In particular, CV cables, which have been widely used recently, may not be used in the cable insulation depending on the manufacturing conditions and the usage environment. Since the water tree that occurs in the equipment may lower the insulation performance in a relatively short period of time and lead to dielectric breakdown, in order to diagnose the insulation strength of the power cable, a withstand voltage test, corona test, leakage current test, etc. Various characteristic tests are conducted. Recently, from the standpoint of reducing the size of the substation site and improving the reliability of power transmission and distribution, a closed-type electric machine that houses electrical equipment such as a switchgear and transformer together with an insulating medium such as gas or oil in the equipment case. Equipment has come to be widely adopted, but in these sealed electric equipment, the high voltage part is not exposed outside the equipment case, so both ends of the electric power cable line directly connected to the sealed electric equipment. In some cases, problems may occur when conducting a withstand voltage test.

FIG. 2 shows a gas insulated switchgear (hereinafter referred to as GIS).
Is shown in the vicinity of the terminal end of the power cable directly connected to the elephant portion of the cable head is attached to the equipment case 1 in which the GIS main body (not shown) is housed. The bottom plate 3 is provided with three in-gas terminal connections 4. A power cable 5 is connected to each of the in-gas terminal connection parts, and the conductor lead-out rod 4a of each in-gas terminal connection part 4 and the GIS are connected.
The high-voltage parts of the above are connected by connecting rods 6, respectively. The side surface of the cable head elephant portion 2 is closed by a case lid 7, and the equipment case 1 is filled with an insulating gas such as SF _{6 at a} predetermined pressure.

When performing a DC withstanding voltage test on a power cable directly connected to a sealed electric device having such a structure, first, the insulating gas such as SF ₆ filled in the device case 1 is removed, and the case lid 7 is removed. To remove the gas in the terminal connection 4 and GIS
Remove the connecting rod 6 connecting between the high pressure part of
As shown in FIG. 3, a three-phase short-circuit fitting 8 is attached between the tips of the conductor lead-out rods 4a of the in-gas terminal connection portion 4. It should be noted that removing the connecting rod 6 connecting between the in-gas terminal connection portion 4 and the high voltage portion of the GIS may cause various inconveniences when a high DC voltage is applied to the high voltage portion of the GIS. So to avoid it. Next, the withstand voltage adapter 10 is attached to the side surface of the cable head elephant portion 2 via the sleeve tube 9. In addition, withstand voltage adapter 1
The terminal connection portion 11 for withstanding voltage test is incorporated in advance in the lower charging port 0, and the charging lead cable 12 having a plug-in structure is connected thereto. Further, a resistor 14 is attached between the conductor withdrawing rod 13 of the terminal connection portion 11 for withstanding voltage test and the three-phase short-circuit metal fitting 8, and the side wall of the withstanding voltage adapter 10 is closed with a case lid 15. Subsequently, the equipment case 1 is evacuated and then filled with an insulating gas such as SF ₆ again.

When the test preparation is completed as described above,
After performing a corona test, a leakage current test, or the like as necessary, a predetermined DC voltage is applied from the other end side of the lead cable 12 for voltage application, the power cable 5 is screened, and its soundness is confirmed. After the above test is completed,
Removal of the withstand voltage adapter and the like, attachment of the connecting rod 6 and the like are carried out in the order substantially reverse to the above order, and the insulating gas such as SF ₆ is filled again to restore the GIS to the operating state.

As described above, when performing a DC withstand voltage test on a power cable line whose both ends are directly connected to a sealed electric device, attachment / detachment of a withstand voltage adapter, attachment / detachment of a connecting rod or the like, or SF There is a problem that it takes a lot of trouble and time for preparatory work such as extracting and filling insulating gas such as ₆ and for cleaning up. Moreover, particularly in recent substations where importance is placed on compactness, the withstand voltage adapter is apt to be restricted by the carry-in passage, the installation space, and the assembling space of the withstand voltage adapter.
Although the size of the phases as a whole is made as small as possible, there are still cases where the withstand voltage adapter cannot be used due to restrictions on the installation space and assembly space.

Even when the withstand voltage adapter cannot be used, in the case of a power cable line in which one end or both ends are directly connected to a sealed electric device via a plug-in type cable termination connection portion, the sealed electric device is The withstand voltage test can be performed without modifying the device case or its inside. FIG. 4 shows a schematic configuration of a power cable line whose both ends are directly connected to a sealed electric device via a plug-in type cable terminating connection part. The sealed electric devices 21 and 22 such as GIS and oil-insulated transformers are shown. A plug-in type in-gas or in-oil terminal box 23, 24 is attached to. Plug-in type cable terminal portions 26 and 27 are formed at both ends of the power cable line 25.
By inserting 7 into the terminal boxes 23 and 24, the sealed electric devices 21 and 22 are electrically connected.

When performing a withstand voltage test on the power cable line thus constructed, as shown in FIG. 5, one cable terminal portion 26 is pulled out from the terminal box 23, and this is used for the withstand voltage test. It is inserted into the middle terminal box 28, and a predetermined high voltage is applied to the conductor lead-out rod 29 via the high voltage lead wire 30 to perform a withstand voltage test. If this pressure resistance test is passed, the cable terminal portion 26 is pulled out from the aerial terminal box 28, and this is reattached to the terminal box 23 to complete the pressure resistance test. In FIG. 5, reference numeral 31 indicates a frame for pressure resistance test, and 32
Indicates a support bushing.

[0009]

As described above, in the case of the power cable line whose one end or both ends is directly connected to the sealed electric device through the plug-in type cable termination connection portion, the device of the sealed electric device is used. The withstand voltage test can be performed without modifying the case or the inside thereof. However, even in this case, conventionally, the cable end portion of the line under test is directly connected to the aerial terminal box 28 for the pressure resistance test, so that it is as narrow as a building or underground substation. In the case of a space, a bare conductor to which a high voltage is applied, that is, the distance between the conductor lead-out rod 29 and the high-voltage lead wire 30 and the space cannot be sufficiently secured, and the withstand voltage test may not be performed. It is an object of the present invention to provide a withstand voltage test method capable of efficiently testing a power cable line whose both ends are directly connected to a sealed electric device through a plug-in type cable termination connection portion.

[0010]

SUMMARY OF THE INVENTION A power cable withstand voltage test method according to the present invention is a power cable line whose both ends are directly connected to a sealed electric device through plug-in type cable termination connection parts. Insert the cable end part extracted from the terminal box into the tapered insertion port of the pressure-resistant prefabricated junction box, and plug the lead cable for voltage application into the other tapered insertion port of the pressure-resistant prefabricated junction box. Type cable end part is inserted and installed in the space for pressure resistance test.
The main feature is that a test voltage is applied to the power cable line from the installed air termination box or power supply equipment via the lead cable for voltage application.

[0011]

According to the withstand voltage test method of the power cable of the present invention configured as described above, even in the power cable line directly connected to the sealed electric device installed in a narrow space,
The withstand voltage test can be performed safely and efficiently.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the method of the present invention will be described with reference to the drawings. FIG. 6 is a vertical cross-sectional view illustrating a pressure-resistant prefabricated junction box used when applying the method of the present invention.
Is a side view (shown in a state where the insulating plug is removed).
In these figures, a pressure-resistant prefabricated junction box 40 has a shielding metal fitting 42 embedded in a power supply unit 41 formed by molding an insulating material such as epoxy resin.
Taper insertion openings 41 on the charging unit on both sides
a and 41b are formed on the mounting carriage 43, and are fixed by a support tool 44 such as a band. When the pressure-resistant prefabricated junction box 40 is not used, the insertion port 41
A lid 45 or an insulating plug 46 is attached to a and 41b. The insulating plug 46 includes a pre-molded insulator 47 having a tapered surface corresponding to the tapered insertion port 41b of the pressure-resistant prefabricated junction box 40, and a high-voltage side shield metal fitting 48 and a low-pressure side shield fixed to the inner and outer ends thereof. It comprises a metal fitting 49 and a mounting plate 51 mounted on the low-voltage side shield metal fitting 49 via a spring 50.

As shown in FIG. 1, the present invention is applied to a withstand voltage test of a power cable line 25 whose both ends are directly connected to sealed electric devices 21 and 22 via plug-in type cable terminal portions 26 and 27. In this case, one cable end portion 26 is pulled out from the terminal box 23, and this is inserted into one taper insertion opening 41a of the pressure-resistant prefabricated connection box 40. A plug-in type cable terminal portion 61 formed at one end of the charging lead cable 60 is inserted into the other tapered insertion opening 41b of the pressure-resistant prefabricated junction box 40.

FIG. 8 shows a state in which the power cable line 25 and the lead cable 60 for charging are attached to the pressure-resistant prefabricated junction box 40. The cable sheath 25a, the cable shielding layer 25b, and the cable semiconductive layer 25c are peeled off in a stepwise manner at the tip of the power cable line 25, and the stress cone 70 is attached onto the exposed cable insulator 25d. The stress cone 70 is composed of a pre-molded rubber-like insulator 70a and a rubber-like semi-conductor 70b integrally molded on the back surface thereof, and the tip of the rubber-like insulator 70a has a tapered shape of the pressure-resistant prefabricated junction box 40. Insertion slot 41
It is a tapered surface having a shape corresponding to a. The rear end of the rubber-like semiconductor 70b is electrically connected to the cable semiconductive layer 25c via the semiconductive mold portion 71. Reference numeral 72 denotes a shaft spring which constitutes a part of the pressing mechanism, and the flange portion 7 attached to the tip of the protection tube 73.
By attaching bolts 75 to the power-applying unit 41 at several places around 4, a strong pressing force is applied to the tapered joint surface between the rubber-like insulator 70a and the insertion port 41a of the pressure-resistant prefabricated junction box 40. The cable conductor 25e exposed at the tip of the power cable 25 is covered with a conductive plug 25f. For this plug, 25 g of wedges are driven in from the tip of the cable conductor 25e,
By expanding the diameter in the vicinity of the tip of the cable, it is electrically and mechanically connected to the cable conductor. Further, the plug 25f and the connection fitting 42 are electrically connected by a multi-ram band 25h inserted between them. Connection between the lead cable 60 for voltage application and the prefabricated junction box 40 for pressure resistance,
The connection is performed in the same manner as the connection between the power cable 25 and the pressure-resistant prefabricated junction box 40.

Referring again to FIG. 1, the plug-in type cable terminal portions 26, 61 are also provided at the other end of the lead cable 60 for charging.
A plug-in type cable terminal portion 62 similar to the above is formed. The plug-in type cable terminal portion 62 is inserted into the aerial terminal box 28 for pressure resistance test.

In the case of the present invention, the aerial terminal box 28 for the pressure resistance test is installed in a wide pressure resistance test space in the vicinity of the installation location of the sealed electric devices 21 and 22, if
Normally, the installation location of the sealed electric devices 21 and 22 is small, and therefore, the bare conductor to which a high voltage is applied, that is, the conductor lead-out rod 29 and the high voltage lead wire 30 can be sufficiently separated from each other and a sufficient space can be provided outdoors. Is installed in. When the test preparation is completed as described above, a high-voltage lead wire 30, an air termination box 28 for a withstand voltage test, a lead cable 60 for voltage application, and a prefabricated junction box for a withstand voltage are supplied from a test power supply device (not shown). 40 to the power cable line 25,
A withstand voltage test is performed by applying a predetermined high voltage of direct current or alternating current. If this withstand voltage test lasts for a predetermined time or more, it is judged as acceptable, and if there is a dielectric breakdown, the breakdown point is repaired or replaced with another good cable, and the withstand voltage test is performed again.
If the withstand voltage test is passed in this way, the cable terminal portion 26 is pulled out from the withstand pressure prefabricated connection box 40, and this is reattached to the termination box 23 to restore the power cable line 25.

In the above withstand voltage test, the sealed electric device 22 connected to the other end of the power cable line 25.
When it is not desired to apply the test voltage to the cable, the cable terminal portion 27 of FIG. 1 is pulled out from the plug-in type termination box 24 to perform the test. In that case, the pressure-resistant prefabricated junction box 40 shown in FIGS. The other one may be used, the lid 45 may be removed, and the cable terminal portion 27 may be inserted into the tapered insertion port 41a. In this way, the test voltage is also applied to the connection fitting 42 of the pressure-resistant prefabricated connection box 40, but an insulating plug 46 is attached to the tapered insertion port 41b, so that the charging unit 41 and the preload unit 41 can be connected to each other. The tapered surface of the mold insulator 47 is tightly fitted to enhance the pressure resistance, and the high-voltage side shield metal fitting 48 and the low-voltage side metal shield fitting 49 arranged at both ends thereof.
Since the electric field is relaxed by the electric field control action of, it can withstand this even if a high test voltage is applied.

As described above, according to the present invention, one end of the power cable line to be tested is connected to the pressure-resistant prefabricated junction box, and a lead cable for voltage application is provided between this and the air-terminated box for the pressure resistance test. Since the test voltage is applied by tying it up, even if it is a power cable line directly connected to a sealed electric device installed in a narrow space, the air terminal box for pressure resistance test can be used in a wide safe voltage range. It can be installed in the test space for testing. Further, the pressure-resistant prefabricated junction box is compact and easy to move, and since it is a plug-in type, the cable under test and the lead cable for voltage application can be easily attached and detached, and the test can be performed efficiently. In the above description, an example in which the other end of the lead cable for voltage application is connected to the air termination box for pressure resistance test is described.
Depending on the case, the other end of the lead cable for voltage application may be directly connected to an output terminal of a power supply facility, for example, a power supply vehicle, and in that case, the same effect as above can be obtained.

[0019]

According to the present invention, a power cable line directly connected to a sealed electric device installed in a narrow space can be tested safely and efficiently.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an embodiment of the system of the present invention.

FIG. 2 is a vertical cross-sectional view showing the vicinity of a terminal portion of a power cable directly connected to GIS.

FIG. 3 is a vertical cross-sectional view showing a state in which a charging lead cable is attached to a terminal end portion of the power cable line of FIG. 2 via a withstand voltage adapter.

FIG. 4 is a schematic explanatory diagram of a power cable line whose both ends are directly connected to a sealed electric device via plug-in type cable termination connection parts.

5 is an explanatory diagram of a case where a withstand voltage test is performed on the power cable line of FIG.

FIG. 6 is a vertical cross-sectional view illustrating a pressure-resistant prefabricated junction box used in the method of the present invention.

FIG. 7 is a side view illustrating a pressure-resistant prefabricated junction box used in the method of the present invention.

FIG. 8 is a vertical cross-sectional view showing a state in which a power cable and a lead cable for voltage application are attached to a pressure-resistant prefabricated junction box.

[Explanation of symbols]

1 ... Equipment case 2 ... Elephant part for cable head 4 ... Gas end connection 5 ... Power cable 6 ... connecting rod 8: 3-phase short-circuit fitting 10 ... Withstanding voltage adapter 11 ... Termination connection for withstanding voltage test 12,60 ...... Lead cable for charging 13 ,. 9: Conductor lead-out rod 14 ... Resistor 21,22 ... Enclosed electrical equipment 23, 24 ... Plug-in type end box 25: Power cable line 26, 27 ... Cable terminal 28 ... Air termination box for pressure resistance test 30 ... High voltage lead wire 31 ... Stand for pressure resistance test 40 ... Prefabricated junction box for pressure resistance 41 ... Electricity charging unit 42 ... Connection fitting that also serves as a shield 43 ... Mounting cart 46 ... Insulation plug 47 ... Premolded insulator 48 ...... High-voltage side shield 49 ...... Low-voltage side shield 51 ... Mounting plate 60 ... Lead cable for charging 61, 62 ... Plug-in type cable terminal 70 ... stress cone 73 …… Protection tube.

Claims (5)

(57) [Claims] 1. In a power cable line whose both ends are directly connected to a sealed electric device via plug-in type cable terminating connection parts, a cable terminal part extracted from one plug-in type terminating box is connected to a pressure-resistant prefabricated connecting box. Insert into one tapered insertion port, plug into the other end of the pressure-resistant prefabricated junction box of the plug-in type cable end of the lead cable for voltage distribution, and connect the lead cable for voltage distribution.
The other end of the cable is installed in the pressure test space.
Connected to the high voltage lead wire through the air termination box for pressure resistance test
Then, through this high voltage lead wire to the power cable line
Power cable line characterized by applying test voltage
Withstanding voltage test method. 2. A plug-in type cable terminating connection at both ends.
Power cable line directly connected to the sealed electrical equipment via
In (1), insert the cable end part extracted from one plug-in type termination box into one tapered insertion port of the pressure-resistant prefabricated junction box, and apply the electricity to the other tapered insertion port of the pressure-resistant prefabricated junction box. Insert the plug-in type cable end of the lead cable for installation into the space for pressure resistance test.
Before the power supply equipment connected via the lead cable for power distribution
It is characterized by applying a test voltage to the power cable line.
Test method for withstanding voltage of power cable lines. 3. A pressure-resistant prefabricated junction box is constructed by embedding a connecting metal fitting that also serves as a shield in a power application unit formed by molding an insulating material, and forming tapered insertion ports on both sides of the power application unit. The withstand voltage test method for a power cable line according to claim 1 or 2, wherein the power application unit is placed on a mounting carriage and is fixed by a support tool. 4. A cable end portion formed on the other end side of a power cable line to which a test voltage is applied is extracted from the other plug-in type termination box, and one of the other pressure-resistant prefabricated junction boxes is connected. It is inserted in the tapered insertion opening, according to claim 1 or請 the other tapered insertion port of the breakdown voltage prefabricated connection box, characterized in that it is mounted an insulating plug
A withstand voltage test method for a power cable line according to any one of claim 2 . 5. A premolded insulator having an insulating plug having a tapered surface corresponding to a tapered insertion port of a pressure-resistant prefabricated junction box, and a high-voltage side metal fitting and a low-voltage side metal shield fixed to the inner and outer ends thereof. 5. A withstand voltage test of a power cable line according to claim 4, comprising a metal fitting and a mounting plate mounted on the low-voltage side shielding metal fitting via a spring.
Way .