JP7456868B2 - Connection body deterioration diagnosis device and connection body deterioration diagnosis method - Google Patents

Description

The present invention relates to a connecting body deterioration diagnosing device and a connecting body deterioration diagnosing method that can be used to detect deterioration of electrical insulators in high-voltage overhead cable connectors and the like.

For example, commercial AC power supplied to each consumer such as a general household or a factory is generally distributed using a power distribution network that passes through a large number of utility poles. In addition, at each utility pole, multiple high-voltage overhead cables that handle high-voltage power, for example around 6kV, are connected to each other, or they are branched from the main high-voltage overhead cable and connected to customer service lines, transformers, etc. Branch routes need to be connected. At such connection locations, high-voltage overhead cable connectors (hereinafter also simply referred to as connectors) are used.

A commonly used connection for high voltage overhead cables is a π-branch connection. In the case of a π-shaped branch connection body, the main line of the high-voltage overhead cable is connected to both left and right ends, and the branch line and a pole drop (PD) adapter are connected to the base end. The high-voltage overhead cable connection body is used in a state where it is installed on a utility pole while being connected to the main line, branch line, etc. of the high-voltage overhead cable.

The connection body is constructed by covering the outer periphery of a cylindrical insulator with an aluminum casing. In addition, a plug-in connector/plug is provided at the terminal of the main line of the high-voltage overhead cable, and the insulator has a plug-in connector/recep inside it for connection (plug-in connection) with this plug-in connector/plug. Store it.

Since the connecting body is constantly exposed to outdoor environments such as wind and rain and wide temperature changes, the internal insulation may deteriorate under the influence of these conditions. If the insulator deteriorates, not only will the connecting body not function, but it will also easily cause short circuits and electric shocks to workers, creating an electrically dangerous situation. Therefore, it is desirable that deterioration of this insulator be diagnosed each time, and that the insulator be replaced with a new one depending on the state of deterioration.

For example, Patent Document 1 discloses a technique for accurately diagnosing partial discharge deterioration of high-voltage equipment such as a high-voltage overhead cable branch connection body for power distribution and preventing power outages due to dielectric breakdown. Specifically, a high frequency current signal detected by a separate current transformer 1 attached to a lead-in cable 6 branched by a connecting body 5 is amplified by an amplifier 2, and then measured by a spectrum analyzer 3. It is stored in the memory within the computer 4. The computer 4 examines the waveform pattern and frequency spectrum of the high-frequency current signal stored in the memory, and diagnoses the degree of partial discharge (degree of insulation deterioration) in the connection body 5.

Patent Document 2 shows a technique for diagnosing insulation deterioration of a high-voltage overhead cable connector at low cost. Specifically, the current waveform flowing through the shielding layer of one of the high voltage overhead cables connected to the high voltage overhead cable connection body is acquired, the commercial power supply frequency component is removed from the acquired current waveform, and the removed current waveform is obtained. measures a time interval that exceeds a predetermined size, and if this time interval is a constant period, it is determined that the insulation has deteriorated.

Patent Document 3 shows a technique for reducing noise in partial discharge signals to make judgments easily and accurately. Specifically, in a method for diagnosing the insulation deterioration state of a high-voltage overhead cable branch connector for electric power distribution, an electrode is installed on the outside of the housing of the high-voltage overhead cable branch connector for electric power distribution so as to capacitively couple the partial discharge generating part with the electrode, and the state of partial discharge caused by insulation deterioration of the high-voltage overhead cable branch connector for electric power distribution is detected as a potential fluctuation signal of the electrode, and the method is characterized in that noise mixed in the signal is removed by taking the difference between the three phases of the signal, and a partial discharge signal with less noise is obtained and insulation deterioration is diagnosed. In addition, in the signal for which the difference is taken, the difference is taken not between the three phases but between multiple electrodes installed on the high-voltage overhead cable branch connector for electric power distribution and between the high-voltage overhead cable branch connectors for electric power distribution on other poles installed on the same distribution line.

Patent Document 4 discloses a technique for detecting a true deterioration signal due to water trees and performing highly accurate diagnosis. Specifically, an AC power source 5 is connected in the middle of a grounding wire 4 connected between the shielding layer 3a of the power cable 3 to be measured and the ground. In addition, the frequency of the AC power supply 5 is an integral multiple of the commercial frequency ± aHz (0<a≦10), and the current flowing from the power cable to the ground via the AC power supply and the ground wire is measured, and the power cable is adjusted based on this current. Diagnose the extent of insulation deterioration in live wire conditions.

Japanese Patent Application Publication No. 2000-2743 JP2019-27785A Japanese Patent Application Publication No. 6-123756 Japanese Patent Application Publication No. 9-318696

However, regarding insulation deterioration of high-voltage overhead cable connectors, deterioration patterns that do not involve discharge phenomena have also been confirmed. Therefore, with the techniques disclosed in Patent Documents 1 to 3, which diagnose insulation deterioration on the assumption that discharge will occur, it is difficult to improve the accuracy of insulation deterioration diagnosis.

In addition, the technology of Patent Document 4 is aimed at high-voltage underground cables and can be applied when the grounding is at one place, but when the shielding is grounded at multiple places, such as a high-voltage overhead distribution line. It cannot be applied to those that are Moreover, the technique of Patent Document 4 was not intended for diagnosis of a connection body using ethylene propylene rubber.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to make it possible to diagnose insulation deterioration even for deterioration patterns that do not involve discharge phenomena, and to provide a connection body in which the shield is grounded at multiple points. An object of the present invention is to provide a connecting body deterioration diagnosing device and a connecting body deterioration diagnosing method that enable diagnosis of the following.

In order to achieve the above-mentioned object, the connecting body deterioration diagnosing device and the connecting body deterioration diagnosing method according to the present invention are characterized by the following (1) to ( 4 ).
(1) Diagnose deterioration of electrical insulation properties in a connecting body that has multiple connecting parts and insulators for connecting high-voltage cables and to which an AC high voltage of a predetermined frequency is applied while the connecting body is in a live state. A connecting body deterioration diagnostic device for
a diagnostic voltage application unit that applies a diagnostic AC voltage having a different frequency from the AC high voltage to a conductor of a power distribution path including the connection body;
Insulation can be achieved by measuring the current flowing through a messenger wire arranged in parallel with the high-voltage cable and connected to the grounding wire or the current flowing through the grounding wire at at least one location on the power distribution path including the connection body. a current measurement unit that detects the magnitude of alternating current flowing through the body;
Of the alternating current detected by the current measurement unit, the level of a specific frequency component obtained as a result of superimposing the alternating current high voltage and the diagnostic alternating voltage is compared with a predetermined threshold, and diagnosis is performed according to the comparison result. A diagnostic section that outputs the results,
Equipped with
The current measurement unit detects the alternating current flowing through the insulator at a plurality of locations for each connection body, and aligns the direction of the alternating current detected at the plurality of locations with the direction of the current caused by deterioration of electrical insulation properties. Equipped with an addition section that adds in the state,
The diagnosis unit performs diagnosis based on the addition result of the addition unit,
Connector deterioration diagnosis device.

( 2 ) Diagnosing deterioration of electrical insulation properties in a connecting body that has multiple connecting parts and insulators for connecting high-voltage cables and to which an AC high voltage of a predetermined frequency is applied while the connecting body is in a live state. A connecting body deterioration diagnostic device for
a diagnostic voltage application unit that applies a diagnostic AC voltage having a different frequency from the AC high voltage to a conductor of a power distribution path including the connection body;
Insulation is achieved by measuring the current flowing through a messenger wire arranged in parallel with the high-voltage cable and connected to the grounding wire or the current flowing through the grounding wire at at least one location on the power distribution path including the connection body. a current measurement unit that detects the magnitude of alternating current flowing through the body;
Of the alternating current detected by the current measurement unit, the level of a specific frequency component obtained as a result of superimposing the alternating current high voltage and the diagnostic alternating voltage is compared with a predetermined threshold, and diagnosis is performed according to the comparison result. A diagnostic section that outputs the results,
Equipped with
The frequency of the diagnostic AC voltage is fixed to a constant frequency obtained by adding a predetermined value to a multiple of the frequency of the AC high voltage,
The diagnosis unit includes a filter that extracts a frequency component corresponding to the predetermined value.
Connector deterioration diagnosis device.

( 3 ) The diagnosis unit selectively uses a plurality of threshold values prepared in advance to diagnose the level of the specific frequency component and determine the degree of deterioration.
The connector deterioration diagnostic device according to (1) or (2) above.

( 4 ) Diagnosing deterioration of electrical insulation properties in a connecting body that has multiple connecting parts and insulators for connecting high-voltage cables and to which an AC high voltage of a predetermined frequency is applied while the connecting body is in a live state. A method for diagnosing deterioration of a connecting body,
a step of applying a diagnostic AC voltage having a different frequency from the AC high voltage to a conductor of a power distribution path including the connection body;
Insulation can be achieved by measuring the current flowing through a messenger wire arranged in parallel with the high-voltage cable and connected to the grounding wire or the current flowing through the grounding wire at at least one location on the power distribution path including the connection body. A procedure for detecting the magnitude of alternating current flowing through the body,
Of the AC current flowing through the detected insulator, the level of a specific frequency component obtained as a result of superimposing the AC high voltage and the diagnostic AC voltage is compared with a predetermined threshold, and diagnosis is performed according to the comparison result. Steps to output results,
has
In the step of detecting the magnitude of the alternating current flowing through the insulator, for each connection body, the alternating current flowing through the insulator is detected at a plurality of locations, and the alternating current detected at the plurality of locations is determined based on the electrical insulation properties. Add the currents generated due to deterioration in the same direction,
In the step of outputting the diagnosis result, a diagnosis is performed based on the added result,
Connector deterioration diagnosis method.

According to the connector deterioration diagnostic device configured as in (1) above, when the connector is in a live state, a high AC voltage of a predetermined frequency and a diagnostic AC voltage generated by the diagnostic voltage application unit are simultaneously applied in a superimposed state to the conductor of the power distribution path. This makes it possible to detect the AC current flowing through the insulator as a specific frequency component whose frequency is significantly different from that of the high AC voltage. By comparing the level of this AC current with a predetermined threshold value, insulation deterioration can be diagnosed. Moreover, since there is no need to apply a special voltage to the ground wire, problems such as electric shock are unlikely to occur and diagnostic work can be easily performed.

Furthermore, according to the connecting body deterioration diagnosis device having the configuration described in ( 1 ) above, in a situation where the current flowing on the particular insulator to be diagnosed is divided into a plurality of different paths due to deterioration of the particular insulator to be diagnosed. This also makes it possible to diagnose insulation characteristics with high accuracy. That is, by adding the alternating currents detected at multiple locations with the directions of the currents caused by the deterioration of the electrical insulation properties aligned, it becomes possible to accurately evaluate the deterioration of the electrical insulation properties of the entire insulator. Furthermore, it is possible to reduce the influence of current flowing through other insulators that are not targeted for diagnosis.

According to the connecting body deterioration diagnosis device having the configuration ( 2 ) above, the alternating current flowing through the insulator can be efficiently detected and evaluated as a frequency component corresponding to a predetermined value. In particular, by setting the predetermined value to a value that is significantly different from the frequency of the AC high voltage, it becomes easy to separate and extract the AC current flowing through the insulator.

According to the connection body deterioration diagnosing device having the configuration ( 3 ) above, by using a plurality of threshold values, it becomes possible to judge not only the presence or absence of deterioration but also the degree of deterioration.

According to the method for diagnosing deterioration of a connecting body having the configuration described in ( 4 ) above, an AC high voltage of a predetermined frequency and a diagnostic AC generated by the diagnostic voltage applying section are applied to the conductor of the power distribution path when the connecting body is in a live state. The voltage is applied simultaneously in a superimposed state. Thereby, the alternating current flowing through the insulator can be detected as a specific frequency component whose frequency is significantly different from that of the alternating high voltage. Insulation deterioration can be diagnosed by comparing the level of this alternating current with a predetermined threshold.
Furthermore, according to the connecting body deterioration diagnosis method having the configuration (4) above, in a situation where the current flowing on the particular insulator to be diagnosed is divided into a plurality of different paths due to deterioration of the particular insulator to be diagnosed. This also enables highly accurate insulation property diagnosis. That is, by adding the alternating currents detected at multiple locations with the directions of the currents caused by the deterioration of the electrical insulation properties aligned, it becomes possible to accurately evaluate the deterioration of the electrical insulation properties of the entire insulator. Furthermore, it is possible to reduce the influence of current flowing through other insulators that are not targeted for diagnosis.

The connector deterioration diagnostic device and connector deterioration diagnostic method of the present invention make it possible to diagnose insulation deterioration even for deterioration patterns that do not involve discharge phenomena.

The present invention has been briefly described above. Furthermore, the details of the present invention will be further clarified by reading the mode for carrying out the invention (hereinafter referred to as "embodiment") described below with reference to the accompanying drawings. .

FIG. 1 is a longitudinal sectional view showing an example of the configuration of one connection body. FIG. 2 is a front view showing an example of the configuration of the end portion of the high voltage overhead cable. FIG. 3 is a block diagram showing a connection state between one connector and a connector deterioration diagnosis device. FIG. 4 is a block diagram showing an example of a current path when a plurality of connectors are connected in series. FIG. 5 is a flowchart showing a characteristic diagnostic operation in the connecting body deterioration diagnostic device.

Specific embodiments of the present invention will be described below with reference to each figure.

<Explanation of the connecting body and high voltage overhead cable to be diagnosed>
An example of the configuration of one connection body 10 is shown in FIG. Further, a configuration example of the end portion of the high voltage overhead cable 20 connected to this connecting body 10 is shown in FIG. The connecting body 10 shown in FIG. 1 is a high voltage overhead cable connecting body, and is used to electrically connect a plurality of high voltage overhead cables 20 and the like to each other.

For example, when a power company that supplies commercial power supplies commercial power to consumers such as factories and households, the power is supplied as a sine wave AC voltage of several kilovolts through a power distribution path including the high-voltage overhead cable 20. Supply commercial power. Because of the need to distribute power over long distances, this power distribution path typically includes a number of utility poles supporting high voltage overhead cables 20. At each utility pole, this connection body 10 is used to electrically connect the high voltage overhead cable 20 on the side close to the power transmission source and the high voltage overhead cable 20 on the side close to the power transmission destination. Furthermore, it is necessary to connect one or more branch lines to the main line of the power distribution route at each utility pole, and supply power from the branch lines to the routes of each customer. A connector 10 is used to connect the branch lines. Therefore, the connecting body 10 is often configured in a π shape as in the example shown in FIG.

An important function required of this connection body 10 is electrical insulation. In other words, electrical insulation is necessary because unless the high voltage current flowing through the high voltage overhead cable 20 is prevented from flowing to areas other than the necessary portions of each utility pole, it may lead to accidents such as electric shock to workers. Therefore, the connection body 10 is provided with an insulator as explained below.
In FIG. 1, the outer periphery of the actual connector 10 is covered with an aluminum casing, but a cross section of the casing is omitted to make the structure of the connector easier to understand.

As shown in FIG. 1, the connection body 10 is used to connect high-voltage overhead cables (see FIG. 2) 20 that transmit commercial power to each other via an intermediary. Further, a predetermined operating voltage is normally applied to the connection body 10 for transmission. The frequency of the operating voltage is 50 Hz in eastern Japan and 60 Hz in western Japan.

The connecting body 10 is integrally molded with ethylene propylene rubber (hereinafter also referred to as EP rubber), semiconductive EP rubber, etc., and includes a cylindrical insulator 11 disposed inside the connecting body 10. . The insulator has a three-layer structure. Specifically, an insulating layer made of EP rubber is placed in the center as a base layer, and an internal semiconductive layer made of semiconductive EP rubber is placed inside this insulating layer. An outer semiconducting layer of semiconducting EP rubber is disposed outside the insulating layer. That is, the insulating layer of the insulator 11 is sandwiched between semiconductive layers from both sides in the radial direction.

Further, the insulator 11 is in electrical contact with the aluminum casing 14 through the external semiconductive layer, and the outer periphery of the insulator 11 is covered by the aluminum casing 14 . The aluminum housing 14 functions as an electrical shielding layer. Further, a part of the insulating layer of the insulator 11 is provided to be exposed to the outside of the connection body 10, and the voltage detection terminal part 12 is provided in this exposed part. The voltage detection terminal portion 12 is covered with a voltage detection terminal cap 13 made of semiconductive EP rubber.

Further, the connecting body 10 and the insulator 11 have a π-shaped outer shape. Main line connecting portions 15 for connecting to each high voltage overhead cable 20 of the main line are arranged at both left and right ends of the insulator 11, respectively. Further, branch connection portions 16 for connection to the high voltage overhead cable 20 of the branch line are arranged at the pair of base end portions of the insulator 11, respectively.

Further, in order to enable connection of the connection terminal 21 provided at the end of the high-voltage overhead cable 20 in a plug-in manner, a plug-in connector receiver (not shown) is incorporated in the trunk connection portion 15 and the branch connection portion 16. The plug-in connector receptacle is surrounded by an insulator. Further, the plug-in connector receiver is integrally provided as a conductor using a copper alloy material having excellent electrical conductivity.
Note that the outer shape of the connecting body 10 is not limited to the π shape. In addition, for example, it may be T-shaped or may have a connection part for a pole drop (PD) adapter.

As shown in FIG. 2, a connection terminal 21 is attached to the end of each high voltage overhead cable 20. This connection terminal 21 has a plug-in connector plug 22, a waterproof tube 24, and a spacer. The plug-in connector plug 22 is arranged at the tip of the connection terminal 21 and is formed in a shape corresponding to the plug-in connector receptacle of the connection body 10. The waterproof tube 24 is disposed at the base end of the connection terminal 21 and is made of semiconductive EP rubber for electrical connection with the shielding layer of the high voltage overhead cable 20. The spacer is disposed between the plug-in connector/plug 22 and the waterproof tube 24 and has the function of insulating the conductor including the plug-in connector/plug 22 from the shielding layer including the waterproof tube 24.

The plug-in connector plug 22 is provided so that it can be easily inserted into the plug-in connector receptacles of the main connection portion 15 and the branch connection portion 16 of the connection body 10 and can be compressed and connected. Further, the waterproof tube 24 is electrically connected by contacting the external semiconductive layer of the connecting body 10.
Note that, in the high-voltage overhead cable 20 as well, the outer periphery of the connection terminal 21 is covered with the housing 26, similarly to the connection body 10.

Further, the connection terminal 21 is provided with a ground line terminal 25 exposed to the outside. This ground line terminal 25 is electrically connected to the waterproof tube 24 of the connection terminal 21 at one end, and connected to a shielding ground line or the like at the other end. At this time, the external semiconductive layer of the connecting body 10 and the waterproof tube 24 of the connecting terminal 21 of the high voltage overhead cable 20 are electrically connected, so that as a result, the external semiconductive layer It will be grounded through.
The plug-in connector plug 22, like the plug-in connector receiver 17, is integrally provided as a conductor from a copper alloy material having excellent electrical conductivity.

The connection body 10 configured as described above is supported by a pedestal installed on each utility pole. Therefore, this connecting body 10 is used in an environment where it is constantly exposed to weather conditions such as wind and rain and outdoor environments such as wide temperature changes. Further, the insulator 11 is constantly exposed to electrical stress. Therefore, the insulator 11 inside the connecting body 10 may deteriorate under the influence of weather, electrical stress, etc., and if the deterioration progresses, the connecting body 10 needs to be replaced. However, replacement involves power outage work in the power distribution system. Therefore, it is desirable to perform this power outage work and replacement work in a planned manner depending on the state of deterioration of the insulator 11 to minimize the impact on households and facilities that require electricity. That is, it is required that the deterioration state of the insulator 11 inside the connecting body 10 can be grasped in advance with high versatility and accuracy.
The connecting body deterioration diagnosing device 30 described below can be used to diagnose the deterioration state of the insulator 11 disposed inside the connecting body 10.

<Configuration example of connecting body and connecting body deterioration diagnosis device>
FIG. 3 shows an example of a connection state between one connector 10 and the connector deterioration diagnosis device 30.
The connecting body deterioration diagnosing device 30 in this embodiment includes a superimposing device 42 and a diagnosing device 45. In the example shown in FIG. 3, the connecting body 10 is the subject of diagnosis by the connecting body deterioration diagnosing device 30. The superimposing device 42 has a function of superimposing a special AC voltage for diagnosis on the AC voltage on the power distribution line 44. The diagnostic device 45 has a function of detecting currents of multiple paths flowing through the insulator of the connecting body 10 as currents i1, i2, and i3, and diagnosing insulation deterioration.

In the example shown in FIG. 3, it is assumed that the voltage of the commercial power supply 41 supplied by the electric power company is 3.8 kV and the frequency f0 is 50 Hz. Based on the frequency f0 of the commercial power source 41, the frequency f1 of the diagnostic AC voltage generated by the superimposing device 42 is determined, for example, as in the following equation.
f1=2・f0+Δf
Δf: Constant sufficiently smaller than f0 (for example, 5Hz)

Therefore, in the example of FIG. 3, the frequency of the diagnostic AC voltage generated by the diagnostic AC power supply 42a included in the superimposing device 42 is set to 105 Hz. This voltage is 100V and a sine wave.

In order to superimpose such a diagnostic AC voltage, the superimposing device 42 is connected in parallel with the commercial power source 41. Further, inside the superimposing device 42, in addition to the diagnostic AC power supply 42a, an isolation transformer 42b and a coupling capacitor 42c are provided. Two output terminals of the diagnostic AC power supply 42a are connected to the primary winding of the diagnostic AC power supply 42a, and one of them is connected to the earth (earth) 43. One end of the secondary winding of the isolation transformer 42b is connected to the commercial power source 41 and the distribution line 44 via the coupling capacitor 42c, and the other end is connected to the commercial power source 41 and the earth 43.

Since the isolation transformer 42b is used, the primary circuit such as the diagnostic AC power supply 42a can be separated from the system so as not to be affected by high voltage. It is assumed that the turns ratio of the isolation transformer 42b is set to 4, for example. In that case, an AC voltage of about 400 V output from the superimposing device 42 is superimposed on the output of the commercial power supply 41.

The capacitance of the coupling capacitor 42c is determined so that the impedance at a frequency of 105 Hz (f1) is relatively small and the impedance at a frequency of 50 Hz (f0) is relatively large. Therefore, the superimposing device 42 can efficiently superimpose the 105 Hz diagnostic AC voltage generated by the superimposing device 42 on the voltage of the power distribution line 44.

The diagnostic device 45 includes a collecting section 45a, a current detecting section 45b, a filter section 45c, and a measuring and diagnosing section 45d.
The collection portion 45a is a portion to which a plurality of lead wires 46, 47, and 48 are commonly connected on the input side of the current detection portion 45b, and has a function of adding up the currents i1, i2, and i3 of the respective paths.

Currents i1, i2, and i3 are current signals indicating measured values in current transformers CT1, CT2, and CT3, respectively. The current transformers CT1, CT2, and CT3 are configured so that each outputs a positive current in the forward direction of the current direction in each path that occurs when the insulator to be measured is degraded. It is clamped to each current path with the orientation aligned. That is, when deterioration occurs in the insulator of the connection body 10 to be measured, the currents i1, i2, i3 flow in the direction from the lead wires 46, 47, 48 toward the gathering portion 45a. Therefore, each of the currents i1, i2, and i3 can be added with the polarities aligned in the collecting portion 45a.

The current detection unit 45b is configured by, for example, an operational amplifier, and can generate a voltage proportional to the input current.
The filter section 45c has a function of extracting only a specific frequency component from the AC signal appearing in the output of the current detection section 45b. In this embodiment, the filter section 45c functions as a bandpass filter that extracts only the component of the frequency (Δf) of 5 Hz.

The present inventors have discovered that the current of a specific frequency component (Δf) obtained by superimposing the diagnostic AC voltage (f1) has a high correlation with the insulation resistance of the insulator in the connecting body 10, that is, with the deterioration. This has been revealed through experiments. Therefore, only signals that have a high correlation with the deterioration of the insulator in the connecting body 10 can be extracted by the filter section 45c.

The measurement/diagnosis section 45d compares the level of the signal component extracted by the filter section 45c, that is, the magnitude of the current value, with a plurality of threshold values prepared in advance, and determines the presence or absence of deterioration of the insulator in the connection body 10 and the degree of deterioration. Perform processing for diagnosis. The details will be explained later.

The pedestal 31 shown in FIG. 3 is installed on one utility pole. The connecting body 10 is supported and fixed on a pedestal 31. In the example of FIG. 3, one end of the high voltage overhead cable 20-1 is connected to the left end of the connecting body 10, and one end of the high voltage overhead cable 20-2 is connected to the right end of the connecting body 10.

Further, a messenger wire 32 provided to prevent unnecessary tension from being applied to the high voltage overhead cable 20-1 is arranged side by side with the high voltage overhead cable 20-1, and one end of the messenger wire 32 is connected to the pedestal 31. It is connected. Similarly, a messenger wire 33 provided to prevent unnecessary tension from being applied to the high voltage overhead cable 20-2 is arranged side by side with the high voltage overhead cable 20-2, and one end of the messenger wire 33 is connected to the mount 31. is connected to. Messenger wires 32 and 33 are each made of steel and are conductors.

The high-voltage overhead cables 20-1 and 20-2 each include a conductor 20a, an insulator 20b, a shielding copper tape 20c, and a sheath 20d. In other words, the cable is configured such that the outer periphery of the conductor 20a, which is a core wire, is covered with an insulator 20b, the outside of the insulator 20b is covered with a shielding copper tape 20c, and the outside of the shielding copper tape 20c is covered with a sheath 20d, that is, an outer skin. has been done.

The conductor 20a of the high-voltage overhead cable 20-1, which is close to the power supply side, is connected to a commercial power source 41 via a distribution line 44 equivalent to the conductor 20a. Furthermore, since the superimposition device 42 is connected to the power distribution line 44, when the connection body deterioration diagnosis device 30 is operating, the AC voltage (50 Hz) output from the commercial power source 41 and the diagnostic output from the superposition device 42 are used. AC voltage (105 Hz) is applied to the conductor 20a of the high voltage overhead cable 20-1 in a superimposed state. Furthermore, the conductor 20a of the high voltage overhead cable 20-1 is electrically connected to the conductor 20a of the high voltage overhead cable 20-2 via the internal conductor of the connecting body 10. Therefore, the AC voltage (50 Hz) of the commercial power supply 41 and the AC voltage (105 Hz) of the superimposing device 42 are also applied to the conductor 20a of the high voltage overhead cable 20-2 in a superimposed state.

At a certain intermediate location on the high-voltage overhead cable 20-1, the shielding copper tape 20c is grounded at a ground point GP1 via a ground line GL1. Further, the central portion of the pedestal 31 is grounded at a ground point GP2 via a ground line GL2. Furthermore, at a certain intermediate location on the high-voltage overhead cable 20-2, the shielding copper tape 20c is grounded at a ground point GP3 via a ground wire GL3.

Further, one end of the messenger wire 32 is connected to the pedestal 31, the other end is connected to the ground line GL1, and the intermediate portion is connected to the ground line GL2 via the ground line G21. Furthermore, one end of the messenger wire 33 is connected to the pedestal 31, the other end is connected to the ground line GL3, and the intermediate portion is connected to the ground line GL2 via the ground line G22. Further, the ground lines GL1, GL2, and GL3 are each connected to a low voltage neutral line 34.

Further, on the left end side of the connecting body 10, the housing 14 is connected to the pedestal 31 at a close position via a grounding line G31. Further, on the right end side of the connecting body 10, the housing 14 is connected to the pedestal 31 at a close position via a grounding wire G32.

The current transformer CT1 of the connecting body deterioration diagnosis device 30 is clamped to surround the outer periphery of the messenger wire 32, and when detecting a current flowing from the connecting body 10 and the frame 31 toward the messenger wire 32, The current transformer CT1 is clamped in the direction in which the signal becomes positive.

Further, the current transformer CT2 is clamped to surround the outer periphery of the grounding wire GL2, and the current flowing through the grounding wire GL2 from the connecting body 10 and the pedestal 31 toward the grounding point GP2 is detected. In this case, the current transformer CT2 is clamped in the direction in which the signal becomes positive. The current transformer CT3 is clamped to surround the outer periphery of the messenger wire 33, and when detecting a current flowing from the connecting body 10 and the mount 31 toward the messenger wire 33, the signal becomes positive. The current transformer CT3 is clamped in this direction.

If the insulator inside the connecting body 10 deteriorates, when the conductor 20a of the high-voltage overhead cable 20-1 and the conductor inside the connecting body 10 are at a positive potential, , the current flows in the direction toward the earth 43.

Typical examples of this current include a current I1 flowing from the insulator in the connection body 10 through the pedestal 31 and the messenger wire 32 to the ground 43, and a current I1 flowing from the insulator in the connection body 10 through the pedestal 31 and the ground wire GL2. A current I2 flowing to the ground 43 and a current I3 flowing from the insulator in the connecting body 10 to the ground 43 through the pedestal 31 and the messenger wire 33 are assumed.

Current transformer CT1 detects the current I1 as current i1. Current transformer CT2 detects the current I2 as current i2. Current transformer CT3 detects the current I3 as current i3. Since the collection unit 45a in the diagnostic device 45 outputs the result of adding up all the currents i1 to i3 (I1 to I3), the diagnostic device 45 calculates The magnitude can be evaluated as the sum of the currents passing through different types of paths.

<Example of current path>
FIG. 4 shows an example of a current path when a plurality of connectors 10-1, 10-2, and 10-3 are connected in series.

In FIG. 4, the pedestal 31-1 is installed, for example, on one utility pole. Further, a pedestal 31-2 is installed on another utility pole adjacent to the utility pole, and a pedestal 31-3 is installed on another utility pole further adjacent to the utility pole. The connecting bodies 10-1, 10-2, and 10-3 are supported and fixed to different frames 31-1, 31-2, and 31-3, respectively. Therefore, it is assumed that the length of the high-voltage overhead cable 20-2 that connects the connecting body 10-1 and the connecting body 10-2 is the distance between utility poles, for example, about 50 m. The same applies to the other high voltage overhead cables 20-1, 20-3, and 20-4. In other words, FIG. 4 shows how the plurality of connection bodies 10 are connected in an actual power distribution path.

Similar to the configuration in FIG. 3, the conductor 20a of the high voltage overhead cable 20-1 connected to one end of the connection body 10-1 in FIG. 4 is connected to a commercial power source 41 and a superimposition device 42, respectively. Further, the conductor 20a of the high voltage overhead cable 20-1 in FIG. 4 is electrically connected to the conductor 20a of the high voltage overhead cable 20-2 via the conductor inside the connecting body 10-1. Similarly, the conductor 20a of the high voltage overhead cable 20-2 is electrically connected to the conductor 20a of the high voltage overhead cable 20-3 via the conductor inside the connecting body 10-2. Further, the conductor 20a of the high voltage overhead cable 20-3 is electrically connected to the conductor 20a of the high voltage overhead cable 20-4 via the conductor inside the connecting body 10-3.

Current transformers CT11, CT12, and CT13 are provided to enable detection of insulation deterioration in connection body 10-1. The current transformer CT11 is clamped to surround the outer periphery of the messenger wire 32-1, and when it detects a current flowing from the connection body 10-1 and the pedestal 31-1 toward the messenger wire 32-1, the current transformer CT11 outputs a signal. The current transformer CT11 is clamped in such a direction that the polarity becomes positive.

In addition, the current transformer CT12 is clamped to surround the outer periphery of the grounding wire GL12, and when detecting a current flowing from the connecting body 10-1 and the pedestal 31-1 to the ground 43 through the grounding wire GL12. The current transformer CT12 is clamped in the direction in which the signal becomes positive. The current transformer CT13 is clamped to surround the outer periphery of the messenger wire 32-2, and when it detects a current flowing from the connection body 10-1 and the pedestal 31-1 toward the messenger wire 32-2, the current transformer CT13 outputs a signal. The current transformer CT13 is clamped in such a direction that the polarity is positive.

Similar to the above, current transformers CT21, CT22, and CT23 are provided to enable detection of insulation deterioration in the connecting body 10-2. The current transformer CT21 is clamped to surround the outer periphery of the messenger wire 32-2, and when it detects a current flowing from the connection body 10-2 and the pedestal 31-2 toward the messenger wire 32-2, the current transformer CT21 generates a signal. The current transformer CT21 is clamped in such a direction that the polarity is positive.

In addition, the current transformer CT22 is clamped to surround the outer periphery of the grounding wire GL22, and when detecting a current flowing from the connecting body 10-2 and the pedestal 31-2 to the ground 43 through the grounding wire GL22. The current transformer CT22 is clamped in the direction in which the signal becomes positive. The current transformer CT23 is clamped to surround the outer periphery of the messenger wire 32-3, and when it detects a current flowing from the connection body 10-2 and the pedestal 31-2 toward the messenger wire 32-3, the current transformer CT23 outputs a signal. The current transformer CT23 is clamped in such a direction that the polarity is positive.

The outputs of the current transformers CT11, CT12, and CT13 are connected to the collecting section 45a-1 of the diagnostic device 45 via lead wires 46-1, 47-1, and 48-1, respectively. Further, the outputs of the current transformers CT21, CT22, and CT23 are connected to the collecting section 45a-2 of the diagnostic device 45 via lead wires 46-2, 47-2, and 48-2, respectively.

In the example of FIG. 4, collective unit 45a-1 is connected to the input of current detection unit 45b-1, and collective unit 45a-2 is connected to the input of current detection unit 45b-2. When multiple connections 10-1, 10-2 are to be diagnosed as in FIG. 4, multiple current detection units 45b-1, 45b-2 may be equipped in one diagnostic device 45 shown in FIG. 3 so that one of them can be selectively used, or multiple collective units 45a-1, 45a-2 may be selectively connected to the input of one current detection unit 45b using a switch or the like.

In FIG. 4, assuming that the insulator has deteriorated at a deterioration point Px near the center of the connecting body 10-2 and the other connecting bodies 10-1 and 10-3 have not deteriorated, the deteriorated insulator The current flows along the paths indicated by the arrows shown in FIG.

That is, in the vicinity of the deteriorated connection body 10-2, there is a current path from the connection body 10-2 and the pedestal 31-2 to the messenger wire 32-2, and a current path from the connection body 10-2 and the pedestal 31-2 to the grounding wire GL22. A current path toward the messenger wire 32-3 and a current path from the connecting body 10-2 and the pedestal 31-2 to the messenger wire 32-3 are formed, respectively. The currents in each of these paths are detected by current transformers CT21, CT22, and CT-23, respectively.

Here, the directions of the currents in the three current paths are aligned in the direction of flowing outward from the connecting body 10-2. Therefore, the detection levels of the currents detected by the current transformers CT21, CT22, and CT-23 are added together as signals of the same polarity at the collecting section 45a-2, so that the insulator of the connecting body 10-2 deteriorates. If so, the output level of the current detection section 45b-2 increases. By identifying the magnitude of this level, the diagnostic device 45 can detect deterioration of the insulator of the connecting body 10-2.

On the other hand, there is also a current path flowing from the connection body 10-2 and the pedestal 31-2 to another adjacent pedestal 31-1 via the messenger wire 32-2. The current in this path is further divided into a current path that flows to the ground 43 via the ground line GL2, and a current path that flows to the ground 43 via the messenger wire 32-1 and the ground line GL11.

Therefore, the current flowing due to the deterioration of the insulator of the connecting body 10-2 is also detected in the current transformers CT11, CT12, and CT13 provided for diagnosing the adjacent connecting body 10-1. However, the direction of the current detected by the current transformer CT13 is the direction flowing from the messenger wire 32-2 toward the pedestal 31-1, and has the opposite polarity (negative polarity). Further, the direction of the current detected by the current transformers CT11 and CT12 is the same as usual, and is positive.

Therefore, when the current transformers CT11, CT12, and CT13 detect the current flowing from the deteriorated connecting body 10-2 side to the connecting body 10-1 side, each signal of the positive polarity current transformers CT11, CT12 When adding the signal of the current transformer CT13 and the signal of the current transformer CT13 of negative polarity in the collecting section 45a-1, the levels of different polarities are canceled out. In other words, the level of the current detected at the collecting section 45a-1 is significantly reduced compared to the level of the current detected at the collecting section 45a-2. Therefore, it is possible to reliably distinguish between the deterioration of the connecting body 10-1 and the deterioration of the connecting body 10-2 due to the difference in current levels in the plurality of gathering parts 45a-1 and 45a-2 located at different positions.

<Characteristic diagnostic operation>
FIG. 5 shows a characteristic diagnostic operation in the connecting body deterioration diagnostic device 30.
The operation shown in FIG. 5 can be realized, for example, as an operation of a computer forming the measurement/diagnosis section 45d. Furthermore, in the example of FIG. 5, it is assumed that diagnosis is performed using three types of threshold values Th1, th2, and Th3 prepared in advance. These threshold values Th1 to Th3 are determined in advance so as to satisfy the conditions of the following relational expression.
Th1<th2<Th3
Further, each numerical value of the threshold values Th1 to Th3 is determined to represent a minute current value within a range of, for example, several tens to several hundreds [nA]. That is, when diagnosing deterioration of the connecting body 10 without discharge, it is necessary to detect a minute current flowing through the insulator.

It should be noted that although the operations shown in Figure 5 are generally assumed to be periodically and repeatedly executed using a computer, it is also possible to realize similar operations through manual operations and judgment by an operator. be. The operation shown in FIG. 5, assuming that it is controlled by a computer, will be described below.

In the first step S11 in FIG. 5, the computer turns on the operation of the diagnostic AC power supply 42a. Since the commercial power source 41 always supplies commercial AC power, as a result of executing S11, the 105 Hz diagnostic AC voltage output from the superimposing device 42 is applied to the distribution line 44 in a state where it is superimposed on the 50 Hz commercial AC power. be done. Then, an AC voltage in which the 50 Hz commercial AC power and the 105 Hz diagnostic AC voltage are superimposed is applied to the conductor 20a of the high voltage overhead cable 20-1.

In step S12, the computer controls the diagnostic device 45 to measure the current level of a superimposed frequency component Δf (eg, 5 Hz) that has a high correlation with insulation deterioration in the connecting body 10-1. That is, after converting the current (i1+i2+i3) added by the collection unit 45a into a voltage by the current detection unit 45b, the filter unit 45c extracts the superimposed frequency component Δf, and the measurement/diagnosis unit 45d specifies the voltage. , grasp the alternating current superimposed current of Δf flowing through the insulator of the connecting body 10-1.

The computer compares the level of the AC superimposed current of Δf measured in S12 with a plurality of threshold values Th1 to Th3 (S13, S15, S17). If the level of the AC superimposed current is smaller than the first threshold Th1, the process advances to S14; if it is smaller than the second threshold Th2, the process advances to S16; if it is smaller than the third threshold Th3, the process advances to S18; If it is equal to or greater than the threshold Th3, the process advances to S19.

When the computer executes step S14, since the detected AC superimposed current of Δf is very small, the computer recognizes that the insulator in the connecting body 10-1 to be diagnosed has not deteriorated, and uses the recognition result as, for example, Display as a numerical or character message.

Further, when the computer executes step S16, since the detected AC superimposed current of Δf is relatively small, the computer recognizes that the degree of deterioration of the insulator in the connecting body 10-1 to be diagnosed is small, and the recognition result is For example, display as a numerical or character message.

When the computer executes step S18, the detected AC superimposed current of Δf is of medium magnitude, so the computer recognizes that the insulator in the connecting body 10-1 to be diagnosed has deteriorated to a medium degree, The recognition result is displayed as a numerical or character message, for example.

When the computer executes step S19, since the detected AC superimposed current of Δf is very large, the computer recognizes that the degree of deterioration of the insulator in the connecting body 10-1 to be diagnosed is large, and for example, -1 Displays a numerical or text message indicating that parts need to be replaced.

For example, as in the example shown in FIG. 4, when the insulator has deteriorated at the deterioration point Px on the connecting body 10-2, when the diagnostic device 45 measures the current in the collecting part 45a-2, Δf. Since the alternating current superimposed current increases, S17 in FIG. 5 is executed, and the computer recognizes the deterioration of the connecting body 10-2. On the other hand, when the diagnostic device 45 measures the current in the collecting section 45a-1, the added current value decreases due to the difference in polarity of the currents in the plurality of paths, so for example, S14 or S16 in FIG. It is recognized that the deterioration of the insulator in the connecting body 10-1 is small.

<Advantages of the connecting body deterioration diagnosis device 30>
In the connecting body deterioration diagnosis device 30 shown in FIG. 3, an AC voltage obtained by superimposing the output of the commercial power supply 41 and the output of the superimposing device 42 can be applied to the conductor 20a of the high voltage overhead cable 20-1. . In addition, by appropriately determining the frequency f1 (for example, 105 Hz) of the diagnostic AC power source 42a with respect to the frequency f0 (for example, 50 Hz) of the commercial power source 41, a specific frequency component Δf useful for diagnosing insulation deterioration in the connecting body 10 can be set. (for example, 5Hz). The inventor has confirmed through experiments that the frequency component Δf of the current flowing through the insulator inside the connecting body 10 has a high correlation with the insulation resistance of the connecting body 10. Therefore, deterioration of the connecting body 10 that does not involve discharge can also be detected based on the level of the frequency component Δf of the current flowing through the insulator inside the connecting body 10. For example, in the diagnostic device 45 in FIG. 3, the filter section 45c extracts the frequency component Δf, so the measurement/diagnosis section 45d identifies the level of the frequency component Δf of the current flowing through the insulator inside the connection body 10. can.

Furthermore, diagnosis can be performed without applying any special voltage to each ground line GL1, GL2, and GL3. Therefore, there is no fear of electric shock even if a worker or the like touches the grounding wires GL1, GL2, GL3, etc. during diagnosis. Further, since it becomes possible to keep the superimposition device 42 and the diagnostic device 45 connected at all times, it is possible to automate the diagnosis, and it is also easy to carry out the diagnosis periodically.

Furthermore, even if the current flowing through the insulator inside the connecting body 10 is divided into multiple paths, the current in each path is detected by multiple current transformers CT1 to CT3 as shown in FIG. By adding the plurality of outputs in the collecting section 45a, it is possible to obtain a current having a high level of correlation with the degree of insulator deterioration.

Further, as shown in FIG. 5, by comparing the current level detected by the diagnostic device 45 with a plurality of threshold values Th1 to Th3, it is possible to specify the degree of deterioration of the insulator in the connection body 10.

In addition, for deterioration of the insulator in the connection 10, the direction of the current flowing through the insulator is taken into consideration, and the polarities of the current directions detected by the current transformers CT1 to CT3 are aligned and added in the assembly unit 45a, thereby improving the accuracy of diagnosing deterioration. In particular, in a situation in which multiple connections 10-1, 10-2, 10-3, ... are connected in series as shown in Figure 4, different current levels are detected at each position of the assembly units 45a-1 and 45a-2, making it possible to distinguish between the deteriorated connection 10-2 and the non-deteriorated connection 10-1.

The connecting body 10 to be diagnosed by the connecting body deterioration diagnosing device 30 is not limited to the π-type, and can be applied to various types of connecting bodies. Further, the application of the connecting body deterioration diagnosis device 30 is not limited to the connecting body 10 of the high voltage overhead cable 20, but can be applied to various power distribution route connecting bodies.

Here, the features of the connecting body deterioration diagnosing device and the connecting body deterioration diagnosing method according to the embodiments of the present invention described above are briefly summarized and listed below in [1] to [5].
[1] A connection body that has a plurality of connection parts and insulators for connecting high voltage cables (high voltage overhead cables 20-1, 20-2), and to which an AC high voltage (commercial power supply 41) of a predetermined frequency is applied. A connecting body deterioration diagnostic device for diagnosing deterioration of electrical insulation properties in (10) in a live wire state of the connecting body,
a diagnostic voltage application unit (superimposition device 42) that applies a diagnostic AC voltage having a different frequency from the AC high voltage to the conductor (conductor 20a) of the power distribution path including the connection body;
a current measuring unit (current transformers CT1 to CT3) that detects the magnitude of the alternating current flowing through the insulator at at least one location on the power distribution path including the connection body;
Of the alternating current detected by the current measurement unit, the level of a specific frequency component (Δf) obtained as a result of superimposing the alternating current high voltage and the diagnostic alternating current voltage is compared with a predetermined threshold, and the comparison result is a diagnostic unit (diagnosis device 45) that outputs a corresponding diagnostic result;
A connecting body deterioration diagnostic device (30) comprising:

[2] The current measurement unit detects the alternating current flowing through the insulator at a plurality of locations for each connection body, and converts the alternating current detected at the plurality of locations into a direction of the current caused by deterioration of electrical insulation properties. an adding unit (aggregation units 45a-1, 45a-2) that performs addition in a state in which the
The diagnosis unit performs diagnosis based on the addition result of the addition unit,
The connecting body deterioration diagnosis device according to [1] above.

[3] The frequency (f1) of the diagnostic AC voltage is fixed to a constant frequency obtained by adding a predetermined value to a multiple of the frequency (f0) of the AC high voltage,
The diagnosis section includes a filter (filter section 45c) that extracts a frequency component (Δf) corresponding to the predetermined value.
The connecting body deterioration diagnosis device according to [1] or [2] above.

[4] The diagnosis unit selectively uses a plurality of threshold values (Th1 to Th3) prepared in advance to diagnose the level of the specific frequency component (Δf) and determines the degree of deterioration (S13 ~S19),
The connecting body deterioration diagnosis device according to any one of [1] to [3] above.

[5] Diagnosing deterioration of electrical insulation properties in a connecting body that has a plurality of connecting parts and insulators for connecting high-voltage cables and to which an AC high voltage of a predetermined frequency is applied while the connecting body is in a live state. A method for diagnosing deterioration of a connecting body,
a step (S11) of applying a diagnostic AC voltage having a different frequency from the AC high voltage to the conductor of the power distribution path including the connection body;
a step (S12) of detecting the magnitude of the alternating current flowing through the insulator at at least one location on the power distribution path including the connection body;
Of the AC current flowing through the detected insulator, the level of a specific frequency component obtained as a result of superimposing the AC high voltage and the diagnostic AC voltage is compared with a predetermined threshold, and diagnosis is performed according to the comparison result. Procedures for outputting results (S13 to S19);
A method for diagnosing deterioration of a connecting body.

10, 10-1, 10-2, 10-3 Connection body 11 Insulator 12 Voltage detection terminal part 13 Voltage detection terminal cap 14 Housing 15 Main line connection part 16 Branch connection part 20, 20-1, 20-2, 20 -3, 20-4 High voltage overhead cable 20a Conductor 20b Insulator 20c Shielding copper tape 20d Sheath 21 Connection terminal 22 Plug-in connector/plug 23 Spacer 24 Waterproof tube 25 Ground wire terminal 26 Housing 30 Connection body deterioration diagnosis device 31, 31 -1, 31-2, 31-3 Frame 32, 32-1, 32-2, 32-3, 32-4, 33 Messenger wire 34 Low voltage neutral wire 41 Commercial power supply 42 Superimposition device 42a Diagnostic AC power supply 42b Insulation Transformer 42c Coupling capacitor 43 Earth 44 Distribution line 45 Diagnosis device 45a Collection section 45b Current detection section 45c Filter section 45d Measurement/diagnosis section 46, 47, 48 Lead wire CT1, CT2, CT3 Current transformer CT11, CT12, CT13, CT21, CT22, CT23 Current transformer GL1, GL2, GL3, G21, G22, G31, G32 Grounding wire GL11, GL12, GL13, GL21, GL22, GL32, GL33 Grounding wire GP1, GP2, GP3 Grounding point i1, i2, i3 Current Px Deterioration point Th1, Th2, Th3 threshold

Claims (4)

A connection for diagnosing deterioration of electrical insulation properties in a connecting body that has a plurality of connecting parts and insulators for connecting high voltage cables and to which an AC high voltage of a predetermined frequency is applied while the connecting body is in a live state. A body deterioration diagnostic device,
a diagnostic voltage application unit that applies a diagnostic AC voltage having a different frequency from the AC high voltage to a conductor of a power distribution path including the connection body;
Insulation can be achieved by measuring the current flowing through a messenger wire arranged in parallel with the high-voltage cable and connected to the grounding wire or the current flowing through the grounding wire at at least one location on the power distribution path including the connection body. a current measurement unit that detects the magnitude of alternating current flowing through the body;
Of the alternating current detected by the current measurement unit, the level of a specific frequency component obtained as a result of superimposing the alternating current high voltage and the diagnostic alternating voltage is compared with a predetermined threshold, and diagnosis is performed according to the comparison result. A diagnostic section that outputs the results,
Equipped with
The current measurement unit detects the alternating current flowing through the insulator at a plurality of locations for each connection body, and aligns the direction of the alternating current detected at the plurality of locations with the direction of the current caused by deterioration of electrical insulation properties. Equipped with an addition section that adds in the state,
The diagnosis unit performs diagnosis based on the addition result of the addition unit,
Connector deterioration diagnosis device. A connection for diagnosing deterioration of electrical insulation properties in a connecting body that has a plurality of connecting parts and insulators for connecting high voltage cables and to which an AC high voltage of a predetermined frequency is applied while the connecting body is in a live state. A body deterioration diagnostic device,
a diagnostic voltage application unit that applies a diagnostic AC voltage having a different frequency from the AC high voltage to a conductor of a power distribution path including the connection body;
Insulation can be achieved by measuring the current flowing through a messenger wire arranged in parallel with the high-voltage cable and connected to the grounding wire or the current flowing through the grounding wire at at least one location on the power distribution path including the connection body. a current measurement unit that detects the magnitude of alternating current flowing through the body;
Of the alternating current detected by the current measurement unit, the level of a specific frequency component obtained as a result of superimposing the alternating current high voltage and the diagnostic alternating voltage is compared with a predetermined threshold, and diagnosis is performed according to the comparison result. A diagnostic section that outputs the results,
Equipped with
The frequency of the diagnostic AC voltage is fixed to a constant frequency obtained by adding a predetermined value to a multiple of the frequency of the AC high voltage,
The diagnosis unit includes a filter that extracts a frequency component corresponding to the predetermined value.
Connector deterioration diagnosis device. The diagnosis unit selectively uses a plurality of thresholds prepared in advance to diagnose the level of the specific frequency component and determine the degree of deterioration.
The connecting body deterioration diagnostic device according to claim 1 or 2 . A connection for diagnosing deterioration of electrical insulation properties in a connecting body that has a plurality of connecting parts and insulators for connecting high voltage cables and to which an AC high voltage of a predetermined frequency is applied while the connecting body is in a live state. A method for diagnosing body deterioration,
a step of applying a diagnostic AC voltage having a different frequency from the AC high voltage to a conductor of a power distribution path including the connection body;
Insulation can be achieved by measuring the current flowing through a messenger wire arranged in parallel with the high-voltage cable and connected to the grounding wire or the current flowing through the grounding wire at at least one location on the power distribution path including the connection body. A procedure for detecting the magnitude of alternating current flowing through the body,
Of the AC current flowing through the detected insulator, the level of a specific frequency component obtained as a result of superimposing the AC high voltage and the diagnostic AC voltage is compared with a predetermined threshold, and diagnosis is performed according to the comparison result. Steps to output results,
has
In the step of detecting the magnitude of the alternating current flowing through the insulator, for each connection body, the alternating current flowing through the insulator is detected at a plurality of locations, and the alternating current detected at the plurality of locations is determined based on the electrical insulation properties. Add the currents generated due to deterioration in the same direction,
In the step of outputting the diagnosis result, a diagnosis is performed based on the added result,
Connector deterioration diagnosis method.

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