JPH10185986A - Antenna for detecting anomaly of cable end processing part and anomaly detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna detecting only abnormal electromagnetic wave at CV cable end processing part and not detecting external noise and an anomaly detector using this antenna. SOLUTION: In the vicinity of end processed part 3 of a CV cable 1, an antenna 5 is fixed. This antenna forms a loop with small diameter (d<=D) by the conductors 42 and 43 of a coaxial cable. This antenna detects electromagnetic wave due to partial discharge generating by the break of cable shield layers 14 and 22 but does not detect external noise with large distance attenuation. Thus, an anomaly detector using this antenna can avoid erroneous judgment due to external noise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna for detecting an abnormality in a CV cable terminal processing unit and an abnormality detection device for the CV cable terminal processing unit using the antenna.

[0002]

2. Description of the Related Art In a power CV cable terminal processing section, a lead tape layer is wound around an outer periphery of a stress cone as a cable shielding layer. The lead tape layer is overlapped at its end with the end of the copper foil tape layer, which is a shielding layer in the cable body, and is electrically connected. Also, a ground lead is led out of the cable from the copper foil tape layer. As a result, the cable has a ground potential cable shielding layer up to the outer peripheral portion of the stress cone of the terminal processing section.

[0003] In the CV cable terminal processing section having the above-described structure, the cable shielding layer composed of the lead tape layer and the copper foil tape layer may be broken due to poor construction, stress due to temperature fluctuation, and the like. Since this torn part floats from the ground potential, a voltage is induced from the cable conductor,
Spark discharge or partial discharge (hereinafter, spark discharge and partial discharge are collectively referred to as “partial discharge”) is generated between the float portion and the ground potential portion. As a method for detecting the float in a live state, an abnormality detection device that detects an electromagnetic wave generated by partial discharge with an antenna has been proposed.

[0004]

However, since the conventional antenna is configured to detect a minute electromagnetic wave emitted from an abnormal part with high sensitivity, the electromagnetic wave from the abnormal part in the CV cable terminal processing unit is not used. , Such as wireless electromagnetic waves, radiated electromagnetic waves due to partial discharges generated in insulators inside or outside the substation or in power transmission lines, and the like, are also detected as external noise. Therefore, in the abnormality detection device using this antenna as a sensor, the electromagnetic wave from the abnormal part in the CV cable terminal processing unit cannot be distinguished from the external noise.
It may be erroneously determined that a float has occurred in the V cable terminal processing unit.

According to the present invention, when a cable shielding layer floats in a CV cable terminal processing section, only electromagnetic waves due to partial discharge generated in the float portion are detected, and external noise is not detected. An object of the present invention is to provide an antenna for use. Further, according to the present invention, when the cable shielding layer floats in the CV cable terminal processing section using the above antenna, it is possible to clearly discriminate between the electromagnetic waves due to the partial discharge generated in the float portion and the electromagnetic waves due to the external noise. It is an object of the present invention to provide an abnormality detection device for a CV cable terminal processing unit.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object. The antenna of the present invention
By processing the end of the coaxial cable for signal transmission, a loop having a diameter smaller than the diameter of the CV cable is formed by the conductor of the coaxial cable. This antenna is mounted near the CV cable terminal processing unit. The signal detected by the antenna is guided to the main body of the abnormality detection device by a coaxial cable for signal transmission.

[0007] The main body of the abnormality detection device monitors whether or not a partial discharge due to the float has occurred in the CV cable terminal processing section in which the antenna is installed by analyzing the electromagnetic wave signal detected by the antenna. The antenna described above is small and formed in a loop shape.
Electromagnetic wave detection sensitivity is low, and the distance attenuation of the detection signal is large. Therefore, although this antenna has a simple structure, it can detect only an electromagnetic wave having a high electromagnetic wave intensity generated at a short distance from the antenna.

By mounting this antenna in the vicinity of the CV cable terminal processing section and using it in the abnormality detection device, the abnormality detection device can clearly discriminate between the electromagnetic waves of partial discharge due to the float and the electromagnetic waves of noise. .
Further, in the present invention, by arranging the antenna in each of the plurality of CV cable terminal processing units, the terminal processing unit where partial discharge has occurred can be located.

[0009]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an outer shape of a terminal portion of a CV cable. In the figure, 1 is a cable, 2 is a terminal provided at the tip of the cable 1, and 3 is a terminal processing unit that processes the tip of the cable 1 to connect the cable 1 to the terminal 2. Reference numeral 4 denotes a ground lead for setting the cable 1 and the cable shielding layer in the terminal processing unit 3 to a ground potential.
Reference numeral 5 denotes an abnormality detection antenna attached to the cable 1 near the terminal processing unit 3.

FIG. 2 shows details of the terminal processing unit. In FIG. 2, for easy understanding, a part is shown in a cross section and a part is shown in a state in which each element is cut open. The CV cable 1 includes a cable conductor 11, an insulator 12, a semiconductive tape layer 13, a copper foil tape layer 14, and a sheath 15. The conductor 11 is connected to the terminal 2 in the upper part of the figure.

The terminal processing unit 3 includes a stress cone 21, a lead tape layer 22, an adhesive polyethylene tape layer 23, a PV
It is composed of a C tape layer 24. This lead tape layer 22
Is wound around the outer periphery of the stress cone 21 in order to set the ground potential to the turning point of the stress cone 21. An adhesive polyethylene tape 23 is wound around the outer circumference of the stress cone 21 and the lead tape layer 22, and a PV
The C tape layer 24 is wound.

The lead tape layer 22 is connected by overlapping its end with the end of the copper foil tape layer 14,
Set to ground potential. In order to secure the potential between the two lead tape layers 22 and the copper foil tape layer 14, wires 31
Is wound and soldered at the portion 32. Further, another wire 33 is wound around the copper foil tape layer 14, soldered at the portion 34, and drawn out as the ground lead wire 4.

An antenna 5 is mounted on the sheath 15 of the cable 1 near the terminal processing unit 3. This antenna 5
Is formed by processing the tip of the coaxial cable 41 for signal transmission. That is, the core wire 42 of the coaxial cable 41 is bent into a loop shape and connected to the shield wire 43.
The loop diameter d of the antenna 5 is smaller than the diameter D of the CV cable 1 (d ≦ D). Thus, the antenna 5 formed in a loop with a small diameter d has a low electromagnetic wave detection sensitivity and a large distance attenuation of a detection signal. Therefore, the antenna 5 detects only an electromagnetic wave having a high electromagnetic wave intensity generated at a short distance from the antenna 5.

This antenna 5 is connected to an abnormality detection device. This state is shown in FIG. Each antenna 5 attached to the plurality of CV cable terminal processing units 3 is connected to the abnormality detection device 6 via each coaxial cable 41 for signal transmission. The abnormality detection device 6 includes a selector box 51 and an abnormality detection device main body 52.

The selector box 51 includes a switch 53 and a selector controller 54. Abnormality detection device body 5
2 is a preamplifier 56, a tuner 57, a CPU 58,
It comprises an I / O interface 59, a relay unit 60, a display 61, and a selector controller 62. The selector controller 54 and the selector controller 62 are connected by a control cable 63.

The detection signal output from each antenna 5 is:
One signal is selected by the switch 53. Switch 53
Are switched under the control of the CPU 58 via the selector controller 62 and the selector control unit 54. The signal selected by the switch 53 is amplified by the preamplifier 56 and input to the tuner 57. Tuner 57
The detection at a plurality of frequency points is performed under the control of the CPU 58, and a signal is output to the CPU 58.

The CPU 58 determines the signal level at a specific frequency and the duration thereof, and determines whether or not there is a partial discharge. Since this determination method is known, a detailed description thereof will be omitted. Then, the CPU 58 outputs the generated portion to the outside by the relay unit 60 and the display 61 via the I / O interface 59.

Next, the operation of the abnormality detecting device will be described. In a normal state, the terminal processing unit 3 does not generate an electromagnetic wave due to partial discharge. Antenna 5 is like external noise,
Since an electromagnetic wave having a distant source is not detected, there is no detection output. In the abnormality detecting device, the output signal of each antenna 5 is sequentially switched by the switch 53. However, since no signal is output in any of the antennas 5, an abnormality occurs in the CV cable terminal processing unit in the CPU 58. It is determined that it has not been performed. Therefore, the relay unit 60 and the display 61 do not perform abnormal output.

Next, in the terminal processing unit 3,
When the lead tape layer 22 or the copper foil tape layer 14, which is the ground potential layer, is torn and floated away from the ground potential due to stress due to temperature fluctuation or the like, a voltage is induced in the float portion. Thereby, a partial discharge occurs between the float portion and the ground potential layer. This partial discharge is detected by the antenna 5 attached at the close distance. In the abnormality detection device, a signal is output from the tuner 57 when the switch 53 selects the corresponding antenna output. The CPU 58 compares the signal levels at a plurality of frequency points output from the tuner 57 with a predetermined reference level, and when each signal level exceeds the reference level and its duration continues for a predetermined time or more, the corresponding terminal processing unit 3 It is determined that a float has occurred. Then, the abnormal unit is output to the outside by the relay unit 60 and the display 61.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, a coaxial cable forming an antenna and a coaxial cable for signal transmission can be formed separately.

[Brief description of the drawings]

FIG. 1 is a view showing an outer shape of a CV cable terminal unit according to the present invention.

FIG. 2 is a sectional view showing details of a CV cable terminal processing unit according to the present invention.

FIG. 3 is a diagram illustrating a configuration of an abnormality detection device main body according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cable 2 ... Terminal 3 ... Terminal processing part 4 ... Grounding lead wire 5 ... Antenna 11 ... Cable conductor 12 ... Insulator 14 ... Copper foil tape layer 15 ... Sheath 21 ... Stress cone 22 ... Lead tape layer 41 ... Coaxial cable 42 ... Core wire 43 ... Shield wire 51 ... Selector box 52 ... Abnormality detection device body 53 ... Switcher 54 ... Selector control unit 55 ... Coaxial cable 56 ... Preamplifier 57 ... Tuner 58 ... CPU 59 ... I / O interface 60 ... Relay unit 61 ... Display 62 ... Selector controller 63 ... Control cable

Claims (2)

[Claims] 1. An antenna mounted near a CV cable terminal processing unit for detecting an abnormal electromagnetic wave generated when a cable shielding layer of the CV cable terminal processing unit floats, and by processing a coaxial cable. Wherein a loop having a diameter smaller than the diameter of the CV cable is formed by a conductor of a coaxial cable.
V-cable terminal processing unit abnormality detection antenna. 2. An antenna according to claim 1, wherein an electromagnetic wave signal detected by the antenna is analyzed.
An abnormality detection device for a CV cable terminal processing unit, comprising: means for determining the presence or absence of a float in a cable shielding layer of the CV cable terminal processing unit.