JPS6073372A - Resistance separation structure in measurement of partial discharge of power cable - Google Patents

Abstract

PURPOSE:To facilitate the setting of a separation resistance value and impedance matching, by exposing the terminal part of a power cable to be measured, and providing a resistance paint layer connecting the space between external semiconductive layers and a resistor connecting the space between external blocking layers. CONSTITUTION:The space between the external semiconductive layers 2, 2 of the separation part 4 of the predetermined terminal part of a power cable to be measured is covered with an insulating layer 3 to provide a resistance paint layer 12 mutually connecting the semiconductive layers 2, 2 while a fixed resistor 13 is connected between the external blocking layers 1, 1 of the separation part 4. Herein, the resistance paint layer 12 relaxes the electric field of the separation part 4 and the influence of partial discharge generated in a terminal connection part 6 in inhibited by its high resistance. In addition, the fixed resistor 13 takes matching with detector impedance 11. By this mechanism, a partial discharge current generated in the side of the cable 7 flows to a partial discharge measuring instrument 15 and a discharge current generated in the side of the terminal connection part 6 is not almost flowed. Therefore, the setting of a separation resistance value and impedance matching can be facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to four resistance separation structures for measuring partial discharge of power cables.

When measuring partial discharges in power cables, it is necessary to detect partial discharges occurring only from the test object (cable section), while MltL is the partial discharge occurring from the terminal connection, etc.

For this reason, conventionally, when measuring partial discharge of turtle cables,
As shown in Figure 1, the specified terminal (II
At the position covering the entire surface of the insulating layer 3, and covering the entire surface of the insulating layer 3, and
11 (anti-cough 5) is applied so as to connect the semi-conductive layers 2 to each other, and the anti-cough value of 11 (anti-cough) of the separated part 4 is set to 11<~bk K K2. Ta.

This allows the terminal i'1liJ connection 6 to the power cable.
and the cables ra+'r and the ground side of medium heat are connected to each other by 7u air) and 1f. Therefore, the terminal connection tt++ 6
The partial discharge pulse current generated from
'! :Eliminating the influence of partial discharge ordered to I connection part 6,
In addition, the cable side can be separated without disturbing the electric field of the separation part 4, and the gap in the cable part insulator (insulator layer 3) that passes between the cable conductor 9 and the external shielding 1ml, due to the hoid. It becomes possible to measure only partial discharge.

In FIG. 1, numeral 10 denotes a stress cone for mitigating discharge at the terminal connection portion, and is constructed by providing a semiconductive layer on the surface of a rubber main body.

In the resistance separation structure described in -, since the resistance paint 5 is used, it has the advantage that it is easy to obtain concentrated high resistance. For example, in order to obtain a high resistance only in the outer semiconducting layer 2, it is necessary to make the length of the FI 11 of the outer semiconducting layer 2 long.However, the matching with the detection equipment impedance 11 11 (anti(ij)
It is difficult to set the voltage to 111 to allow the terminal to pass through, and therefore there is a risk of a partial discharge including partial discharge at the terminal connection section 6.

The present invention was developed in view of the above circumstances, and its purpose is to easily set the separation resistance value (not only to easily set the separation resistance value, but also to prevent matching with the impedance of the detection equipment).
The purpose is to provide an anti-separation structure.

That is, the present invention provides i'li! of a power cable for measuring partial discharge. At a predetermined location at the end of j, the outer 93 shielding layer and the outer semiconducting layer of the region are peeled off to form a separation part in which the insulating layer protrudes over the entire circumference, and the separation part allows -))^11
Saw between the external semiconducting layers and connect them to each other 1
1 (In addition to providing an anti-cough material layer, the separation part separates iMI+
1j (
It is characterized by being equipped with a resistor.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows an example of the resistance isolation structure of the present invention.
FIG. In addition, it is not shown in Figure 1 ((IX
The same reference numerals are given to the same parts as those shown in FIG.

In this embodiment, an insulator 1j'i 3 is covered between the outer semiconducting layers 2, 2 of the separation part 4, and the outer semiconducting layers 2, 2 are
11 (Anti-cough 1611t512 is installed, and a fixed resistor 13 is installed between the external RB & Hei-brow 1 and 1 of Ml1 section 4 to connect them to each other, and these 1JL resistors are Finished with paint layer 12 and fixed resistor 13
(The ground side of the connection part 6 and the ground side of the cable part 7 are electrically separated.

Here, the roles of the resistive paint layer 12 and the fixed resistor 13 are different. In addition, the resistive paint 1 Akebono 12 alleviates the electric field in the separation part 4 and also prevents the partial discharge generated in the terminal connection part 6 from affecting the cable 7 side due to its high resistance. The resistance value of this resistive paint layer 2 is IMΩ/cm or more F in the gable orientation direction.
The resistance value is set to be ten times or more the resistance value of the fixed ++1 resistor 13.

The fixed resistor 13 is used to match the impedance of the detection equipment 11, and its resistance value varies depending on the cable under test and the measurement circuit, or is usually set within a range of IKΩ to several Ω. be done. If the detection equipment impedance 11 is small, it is sufficient that it is 50Ω or more.

FIG. 3 shows a power cable partial discharge measuring circuit. During measurement, g19 generated from the terminal connection 6, etc.
In order to separate the partial discharge, the above-mentioned resistance separation structure is provided at a predetermined location at the terminal of the power cable A, and the high voltage test circuit 1
4) Connect the discharge measuring device I5.

As a result, as shown in the equivalent circuit of FIG.
The partial discharge current generated at 60% of the connection points is the resistance/heat fl[
i ] 2 and the high resistance R1 of the fixed resistor 13, and is led to the grounding line 8 side of the low resistance R7.

At this time, since the fixed 11 is matched with the detection equipment impedance 11 by the resistor 13, the current generated on the terminal connection G side (fJj branch 71i) is connected to the grounding wire 81JI
It is easier to lead to I+. Moreover, the disturbance of the electric field in the separation part 4 is also alleviated by the J) U anti-cough material layer I2.

Therefore, the partial discharge current generated in the cable 711111 flows through the partial discharge regulator 15, and the partial discharge current generated on the terminal connection portion 6 side hardly flows.

For example, when measuring the electrical discharge (for example, using the following tea juice), a partial discharge of approximately 2 (l l) C generated at the road body 1 contact part 6 was approximately 0.21) on the cable part 7 side. Hold down to C; 1
・I got 11.

Measuring device (11) Test cable: rIJ of 33KV CV cable separation section 4: Resistance value of 3cm resistive paint layer 12: Resistance value of 1MΩ fixed resistor 13...I KΩ test voltage...
・・・・・・・・・・・・・・・・・・601(V Partial discharge 4(S regulator 15・・・・・・・・・・・・E RΔ
-6 type (manufactured by Rohinson, UK) FIG. 5 shows another embodiment of the present invention. In this other embodiment, a variable resistor 16 is provided in place of the fixed resistor 13. In this case, the resistance value of the resistive paint layer 12 is 1M07cm or less in the cable length direction, and the resistance value of the variable resistor 16 is 1M07cm or less in the cable length direction.
is set higher than the maximum resistance value of

When using the variable resistor 16, it is possible to adapt to changes in cable size or detection equipment.

As explained above, according to the present invention, an external shielding layer and an external layer are provided at a predetermined location at the αj1,1 end of the heavy cable cable for measuring partial discharge. ii layer is peeled off to form a separation part in which the insulating layer is exposed over the entire circumference, a resistive paint layer is provided between the external semiconductive layers separated by the separation part to connect them to each other, and a layer I' Since a resistor is provided between the external shielding layers separated by the 11th section, the isolation resistance value of the separating section is matched to the one that suppresses disturbance of the electric field and the detection impedance of the device. You can set the settings separately.

Therefore, compared to the conventional case where the resistive paint alone has two roles: preventing disturbance of the electric field at the separation part and separating the low voltage electrode between the terminal θ1j11 connection side and the cable side, The task of setting the separation resistance value to an appropriate value can be easily performed six times.

In other words, since the range of resistance values that suppress the disturbance of the electric field is wide, it is easy to set this with a resistor of 1"l, and the detection I impedance is determined by the measurement circuit condition (). Since it changes depending on the 1st grade, ``ζ resistance 2:
)'s 11V, anti-jil' (can be set as &J).

Therefore, when measuring the partial discharge of the power cable, the influence of the partial discharge at the 11 termination ports can be suppressed as much as possible.

[Brief explanation of the drawing]

Figure i1 is an enlarged sectional view of the main part of the conventional resistance isolation structure,
The figure shows an example of the structure of the resistor l1lIt of the present invention.
An enlarged sectional view of Jl, Part 3 is a partial discharge measurement circuit diagram of a power cable, and Figure 4 is an equivalent circuit diagram of the Pi11 resistance structure.
FIG. 5 is an enlarged 11-ji view of the main parts showing another embodiment of the anti-separation structure of the present invention. Δ... Electric cable, l... External shielding layer , 2... External semiconducting layer, 3... Insulator layer, 4... Separation section, 11... Detection equipment impedance, 12... ...Resistance paint layer, 1
3... Fixed resistor, 16... Variable resistor.

Claims (7)

[Claims] (1) Section] Predetermined terminal M of the power cable for measuring discharge
At the l+ position, the external shielding layer at the 11th (position) and the outer R8 semiconductive shoulder are peeled off to form a separation part in which the insulating layer is exposed over the entire circumference, and between the external semiconducting layers separated by the separation part, and a resistive paint layer connecting them to each other, and the minute δ
1. A resistor All structure for partial discharge measurement of electric power cables, characterized in that resistors are provided between layers separated by 11 parts and 1 part to connect them to each other. (2) The resistance separation structure for partial discharge measurement of heavy power cables according to claim 1, wherein the resistor is a fixed resistor. (3) A resistance isolation structure for measuring partial discharge of a power cable according to claim 1, wherein the resistor is a variable resistor. (4) The resistance value of the fixed resistor is a value that matches the detection impedance of a partial discharge measuring device, and the resistor is used for partial discharge measurement in power detection according to claim 2. Separate structure. (5) The variable range of the resistance value of the variable resistor is within a range that can match the detection impedance of a partial discharge meter. Resistance in the same J discharge measurement)! '! It
structure. (6) II (Resistance value of anti-cough O'1 layer? Axis 117!
less than IMΩ/cm per unit length in the direction i & j,
The resistance isolation structure for partial discharge measurement of a power cable according to claim 2, characterized in that the resistance is 11 (only 10 times or more) that of the fixed resistor. (7) The resistance value of the resistive paint layer is not less than IMΩ/cm per unit length in the axial direction, and is not less than the maximum resistance value of the variable resistor. Resistance pitt structure used in partial discharge measurement of power cables described in Section 3.