JPH01189571A - Testing apparatus of cable - Google Patents

Abstract

PURPOSE:To make a measuring operation efficient and precise, by a method wherein a standard capacitor to be used for measurement of a cable to be tested is incorporated in a cable terminal box for connecting a power source for electrification and the cable mutually. CONSTITUTION:A low-voltage-side electrode 21 is disposed on the inner wall of a cable terminal box 20 so that it is opposite to a high-voltage shield 25A. Between the shield 25A and the electrode 21, a form and others are selected so that an electrostatic capacity equivalent to a standard capacitor to be used on the occasion of measurement of induction tangent, i.e. tan delta, as one of characteristic tests of a cable 10 to be measured is generated. In other words, the standard capacitor is so formed as to obtain the electrostatic capacity by this shield 25A and the low-voltage-side electrode 21 made to be opposite thereto. By using such an apparatus as started above, the standard capacitor accommodated before-hand in the terminal box 20 can be used for measurement of the cable 10 when a high voltage from a power source 1 for electrification is impressed on the cable from an aerial bushing 3 through a bus line 15.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a cable testing device for measuring electrical characteristics of high voltage cables.

(Technical background of the invention and its problems) In recent years, with the increase in power transmission capacity, the development of high voltage cables for ultra-high voltage power transmission has been actively promoted. In developing this high-voltage cable, it is essential to conduct various electrical property tests, such as tests on its insulation properties and long-term load properties.

Here, using FIG. 3, a schematic configuration of a conventionally commonly used cable testing device will be explained.

A cable 2 for outputting the high voltage generated by this power supply is led out from a power supply 1 for charging this device.

The terminal end of this cable 2 is connected to an air bushing 3. A cable termination box 4 made of epoxy resin or the like is integrally fixed to the base of the aerial bushing 3. Inside this cable termination box 4, for example, S F s
It is filled with an insulating gas 5 such as. Further, the high voltage is guided to the connection electrode 7 by a connection conductor such as a bus bar 6.

On the other hand, at the terminal portion of the cable under test 10, a terminal processing section 8 is formed by a stress cone or the like. This terminal processing section 8 is inserted from one end of the cable termination box 4,
It is sealed by the connection cover 9. Thereafter, the peripheral portion of the terminal processing section 8 surrounded by the cable termination box 4 and the connection cover 9 is evacuated and filled with insulating oil. In this way, from the charging power source 1 to the cable under test 10,
A predetermined test high voltage is applied. Note that the terminal of the cable under test 10 is terminated by a dummy (not shown).

By the way, one of the cable characteristic test items is the measurement of dielectric loss tangent, that is, tan δ.

A Schering bridge is used for R9t to measure this tan δ. During the Schering Bridge,
Standard capacitors are included.

In FIG. 3, an example of the connection is shown by a broken line, and the standard capacitor 30 is connected, for example, so that one end thereof is connected to the tip of the air bushing 3 and the other end is grounded. Alternatively, connect the other end of the cable 10 to be measured with another air bushing 3.
', and a standard capacitor 30' is connected here.

However, in any of the above cases, a special space is required to install the standard capacitor 30 near the aerial bushing 3 or 3', and lead wire replacement work at a high place is required. In addition, corona tends to occur from high-pressure parts, which may affect the measurement results. Furthermore, the third
If the bushing 3 is directly connected to the energizing power supply 1 shown in the figure, the lead wire for connecting the standard capacitor 30 may not be drawn out. In this case, as shown on the right side of Figure 3, the other end of the cable under test 10 must be terminated in an air bushing 3', and a standard capacitor 30' must be attached here. .

In this case, it is necessary to separately install an air termination 3', which also requires a large space and a considerable amount of time for installation work.

(Object of the Invention) The present invention has been made with attention to the above points, and by incorporating a standard capacitor into a cable termination box, it is possible to omit the complicated work such as construction for externally attaching a standard capacitor. At the same time, the purpose is to provide a cable testing device that improves measurement accuracy.

(Summary of the Invention) The cable testing device of the present invention includes a power supply for applying a high voltage to the cable under test, an aerial bushing electrically connected to the power supply for power supply, and an air bushing that is integrated with the aerial bushing. and a cable termination box that receives the terminal of the cable under test, and the cable termination box includes a connecting conductor that leads the high voltage from the aerial bushing to the terminal of the cable under test, and a connecting conductor that leads the high voltage from the aerial bushing to the terminal of the cable under test. A low-voltage side electrode is arranged opposite to each other, and a standard capacitor for testing is formed by the capacitance generated between the connecting conductor and the low-voltage side electrode.

(Embodiment of the invention) FIG. 1 is a schematic diagram showing an embodiment of the cable testing device of the invention.

In the figure, a cable 2 is drawn out from a power source 1 for charging, and the terminal end of this cable 2 is connected to an air bushing 3. A cable termination box 20 is provided at the base of the aerial bushing 3, and the inside thereof is filled with an insulating gas 5 such as SF6.

Inside the cable termination box 20, the busbar 15 is connected to the subgas bushing 12. In the present invention, this bus bar 15 is called a connection conductor. A cable connection sleeve 16 is connected to the other end of the bus bar 15 . The tip of the cable to be measured 1o is inserted into this cable connection sleeve 16.

The other end of this cable to be measured 10 is insulated and protected by a dummy 18. The connection portion between the bushing 12 in the gas and the bus bar 15 is protected by a high pressure shield 25A. In addition, the cable connection sleeve 16 and the bus bar 15
The connection portion with is protected by a high voltage shield 25B.

Here, in the cable testing apparatus of the present invention, a low voltage side electrode 21 is arranged on the inner wall of the cable termination box 2o so as to face the high voltage shield 25A. The shape etc. of the high voltage shield 25A and the low voltage side electrode 21 are selected so that a capacitance equivalent to that of a standard capacitor used for tan δ measurement of the cable to be measured 10 is generated. There is. In addition, in the peripheral part of the low voltage side electrode 21,
The guard electrode 2LA is provided to make the distribution of electric lines of force uniform. A lead wire 22 is connected to the back surface of the low voltage side electrode 21, and is drawn out from the cable termination box 20 and connected to a ground terminal (not shown) or the like.

By using the cable testing device with the above configuration, when applying a high voltage from the energizing power supply 1 to the cable under test 10 from the aerial bushing 3 via the bus bar 15, it is possible to A standard capacitor housed can be used for the measurement.

Incidentally, in the above embodiment, this standard capacitor has a capacitance obtained by the high voltage shield 25A and the low voltage side electrode 11 opposed to the high voltage shield 25A. Of course, it goes without saying that this high-voltage shield 25A is directly electrically connected to the bus bar 15, but various other configurations of the capacitor can be considered.

FIG. 2 shows an embodiment of a cable testing device that is a more practical configuration of the device shown in FIG.

In FIG. 2, the power source 1 for charging is configured to be connected to the cable under test 10 via a so-called GIS (Gas Insulated Switch Type Air Termination 20) type device. This charging power source 1 is composed of, for example, a high voltage transformer. An oil-submerged bushing 11 and a gas-submerged bushing 12 are connected to this power supply 1 in this order.

The part after this gas-submerged bushing 12 is a GIS, to which a surge protection resistor 13 and a standard capacitor 14 are connected. Further, the terminal portion of the bus bar 15 is branched into two, and is insulated and protected by connection sleeves 16A and 16B. This connection sleeve is made of, for example, epoxy resin. In this embodiment, these two connecting sleeves 16A, 16B will be referred to as the first connecting sleeve 16.

On the other hand, second connection tubes 17 are provided in advance at both ends of the cable under test 10 to insulate and protect the terminals. The first connecting sleeve 16 and the second connecting sleeve 17 are configured to be removably fitted into each other.

The second connecting sleeve 17 attached to both ends of the cable under test 10 is connected to the first connecting sleeve 16A.

16B, and a secondary current is supplied to this cable 10 under test using a current transformer 19. For example, if a predetermined high voltage is applied to the cable under test 10 through the first connection tubes 16A and 16B while passing a current of 4000 A through the cable under test 10, a test that is closer to the usage condition on an actual line can be performed. can be done.

Now, in the above-mentioned device, the standard capacitor 14 is configured such that the low voltage side electrode 21 is placed opposite to a branch line 15B that branches off a part of the bus bar 15. of course,
In order to obtain sufficient capacitance, the diameter of this branch line 15B may be increased or a cylindrical electrode may be provided coaxially with the branch line 15B.

(Effects of the Invention) The cable testing device of the present invention described above incorporates a standard capacitor used for cable measurement into the cable termination box for mutually connecting the charging power source and the cable under test. Therefore, it is not necessary to secure a place to install the capacitor or to perform capacitor installation work, and it is possible to improve the efficiency and precision of the measurement work.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the cable testing device of the present invention, FIG. 2 is a schematic diagram showing a more specific embodiment thereof, and FIG. 3 is a schematic diagram of a conventional cable testing device. 1---------1--Electrifying power supply, 3----------- Bushing all at once, 5-----
-------Insulating gas, 10-----Cable under test, 12--
-1----Ga man bushing, 15-------1--
Bus bar (conductor for connection), 16---------Cable connection sleeve, 18-----Dummy, 20------1--Cable termination box, 21 −−1−
------Low voltage side electrode, 22-----1--Lead wire. (1 other person) 1-1-----------Electrical power supply 3-----1--Air bushing 5-------
---1 Insulating force base 10--------One wide test cable +2--1--
-----F'Pill bushing 15------1 wire (↑Button Akatsuki conductor) 16---------Cable connection tube old------
------Dummy nod--1111111 Cable termination sheath 21 -------I [艮1] Electrode 22----
------Sword line Figure 1

Claims (1)

[Claims] A charging power source that applies a high voltage to the cable under test, an aerial bushing that is electrically connected to the charging power source, and a cable termination box that is integrated with the aerial bushing and receives the terminal of the cable under test. The cable termination box is provided with a connecting conductor for guiding the high voltage from the aerial bushing to the terminal of the cable under test, and a low voltage side electrode disposed opposite to the connecting conductor, A cable testing device characterized in that a standard capacitor for testing is formed by capacitance generated between a connecting conductor and the low voltage side electrode.