JP2000241490A - Partial discharge measuring lead wire connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To connect easily a lead wire to a metal shell pipe. SOLUTION: Power cables 1a, 1b are connected through an insulating connection part 2, and metal shell pipes 3a, 3b of the insulating connection part 2 are insulated by an insulating cylinder 4. Lid parts 6 are fixed by bolts 7 on gas injection holes 5a, 5b of the two metal shell pipes 3a, 3b. A tapped hole is formed on the upper part of the lid part 6, and a screw 10 is threaded into the tapped hole to fix a lead wire having a terminal installed on the head thereof. In this formation, a high voltage is applied on the power cables 1a, 1b, to generate partial discharge on an insulator of the insulating connection part 2, then, a high-frequency pulse is induced in conductors of the power cables 1a, 1b and in the metal shell pipes 3a, 3b, and the high-frequency pulse in the metal shell pipes 3a, 3b flows through the lead wire 12, to generate a potential difference between the both ends in proportion to the magnitude of the high-frequency pulse. The potential difference is detected by a measuring circuit 13 to measure the partial discharge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead wire connecting structure for measuring partial discharge at an insulated connection portion or a terminal connection portion of a power cable line.

[0002]

2. Description of the Related Art In order to measure a partial discharge of an insulated connection, a method of measuring a partial discharge of an insulated connection by attaching a metal foil electrode to the outside of a metal tube is disclosed in, for example, Japanese Patent Publication No. 6-71.
No. 48, for example. This method enables measurement without touching the metal electrode portion on the metal sheath side.

In this case, the size of the foil electrode is determined such that the capacitance C between the foil electrode and the metal sheath is equal to or larger than a predetermined value. This condition requires that the impedance Zc of the capacitance is negligible compared to the detection impedance Rd for measurement, that is, Rd >> Zc is required.

[0004]

However, at the time of construction of this insulated connecting portion, it is necessary to consider the space required for mounting a foil electrode having a sufficient area. There are restrictions on the location and area for attaching the foil electrode, and forcing the space is sometimes a problem.
In some cases, as in the case of the terminal connection, an insulating treatment is required on the metal. In order to achieve this condition, there may be cases where the construction of the insulated connecting portion is excessively performed, and a method that does not consider the area of the electrode is desired.

Japanese Patent Publication No. 6-7147 discloses an example in which measuring devices are connected to metal tubes on both sides of an insulating cylinder without using a foil electrode to measure partial discharge.

However, in this example, in order to attach the lead wire, a terminal attaching portion must be provided on the metal body tube by welding or the like, and the construction is extremely troublesome. Further, in this example, the measuring instrument can be connected using a cross-bond ground terminal directly connected to the metal tube, but this ground terminal is usually provided at an end portion of the tube, that is, at an insulated connection portion. It is provided in a part far from the insulating cylinder in the middle part. Therefore, when the lead wire of the measuring instrument is attached to the ground terminals on both sides of the insulating cylinder, the wire length must be increased.

In general, partial discharge measurement is performed using a high-frequency signal. However, as the lead wire of the measuring device becomes longer, extra impedance is interposed, which causes a bad influence on accurate measurement.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a partial discharge measurement lead wire connection that can easily connect a lead wire to a metal body tube and shorten the lead wire length when performing the same measurement without using a foil electrode. It is to provide a structure.

[0009]

In order to achieve the above object, a lead connection structure for partial discharge measurement according to the present invention comprises:
In a lead wire connection structure in the case of measuring a partial discharge at a connection portion of a power cable line provided with a metal body tube on both sides of an insulating cylinder, a metal compound of a waterproof compound injection hole provided in the metal body tube is provided. A lead wire is fixed to the lid.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. FIG. 1 shows an embodiment, in which power cables 1 a and 1 b are connected via an insulated connecting portion 2, and two metal body tubes 3 a and 3 b of the insulated connecting portion 2 are insulated by an insulating tube 4. Two metal body tubes 3a, 3b
Are originally provided with waterproof compound injection holes 5a, 5b, and these waterproof compound injection holes 5a, 5a,
As shown in FIG.
It is fixed by.

The injection holes 5a and 5b are provided in the metal tube 3
In order to improve the moisture resistance of the insulated connecting part 2 by filling the inside of the waterproofing compound with the inside of a and 3b, the waterproofing compound is provided after the connecting part is assembled. The injection holes 5a and 5b are usually provided at an upper portion relatively close to the insulating cylinder 4 in consideration of the compound injection efficiency, workability, and the like.

In this embodiment, the lead wires 12 extending from the partial discharge measuring device 13 are utilized by using the lids 6 for closing the waterproof compound injection holes 5a and 5b.
12 is attached. The injection holes 5a and 5b are provided in the metal tube 3.
The lids 6, 6 are tightly joined by bolts 7. If the lead wires 12, 12 are attached to these lids 6, 6, the leads 6 and 6 are connected to the metal body tubes 3a and 3b. This means that the lines 12, 12 are directly connected. That is, new processing for attaching the lead wires 12 and 12
The electrical connection can be made without making the connections a and 3b.

In this embodiment, for example, a thick portion 9 is provided on the upper portion of the lid portion 6, a screw hole 8 is formed in the thick portion 9, and a screw 10 is screwed into the screw hole 8. By
A lead wire 12 having a terminal 11 attached to the tip is fixed. As a method of attaching the lead wire 12 to the lid 6, a method of removing the fixing bolt 7 of the lid 6 and fitting the terminal 11 can be considered, but if this method is adopted, the bolt 7 is loosened to connect moisture. There is a risk of intrusion into the unit. However, when the thick portion 9 is separately provided in the lid portion 6 to form the screw hole 8 which is not a through hole as in the present embodiment, there is a possibility that moisture may enter when the lead wire 12 is attached or detached. As a result, the measurement can be performed while maintaining the airtightness in the connection portion.

The two lead wires 12 are connected to a measuring circuit 13 via a capacitor C which cuts off commercial frequency components.

In this configuration, the power cables 1a, 1a
When a partial discharge occurs in the insulators of the power cables 1a and 1b of the insulating connection portion 2 by applying a high voltage to the inner conductor of the power cable 1b, the conductors of the power cables 1a and 1b and the metal tube 3
a, and 3b, high-frequency pulses are induced in the metallic body tubes 3a, 3b.
The high frequency pulse b flows through the lead wire 12, and a potential difference is generated between the two lead wires 12 in proportion to the magnitude of the high frequency pulse. This potential difference is detected by a known measuring circuit 13 to measure the partial discharge.

The present invention can be similarly applied to a terminal connection.

[0017]

According to the lead wire connection structure for partial discharge measurement according to the present invention described above, it is possible to easily connect the lead wire to the metal tube, and it is not necessary to secure a necessary area for the foil electrode. I can do it. Furthermore, since the lead wire is attached by using the lid that covers the hole for injecting the waterproof compound, which is provided relatively close to the insulating cylinder, the length of the lead wire can be considerably shortened as compared with the conventional method. it can. This is in partial discharge measurement using high frequency,
As a result, the effect of the impedance interposed in the measurement circuit can be reduced, and more accurate partial discharge measurement can be performed.

Further, according to the structure of the second aspect, the airtightness inside the insulated connecting portion of the cable is not impaired at the time of attaching and detaching the partial discharge measuring instrument, and there is no obstacle such as invasion of moisture into the inside of the connecting portion. Will not occur.

[Brief description of the drawings]

FIG. 1 is a configuration diagram.

FIG. 2 is a perspective view of a main part.

[Explanation of symbols]

 1a, 1b Power cable 2 Insulated connection 3a, 3b Metal tube 4 Insulation cylinder 5a, 5b Gas injection hole 6 Lid 9 Screw hole 10 Screw 12 Lead wire

Claims (2)

[Claims] In a lead wire connection structure for measuring a partial discharge at a connection portion of a power cable line provided with a metal body tube on both sides of an insulating tube, a waterproof compound injection hole provided in each of the metal body tubes. A lead wire connection structure for partial discharge measurement, wherein a lead wire is fixed to a metal lid part of the part. 2. A partial discharge measuring device according to claim 1, wherein a screw hole is formed in said lid portion, a screw is screwed into said screw hole, and a lead wire is fixed to said lid portion by said screw. Lead wire connection structure.