JP2022014370A - Connection body deterioration diagnostic device and connection body deterioration diagnostic method - Google Patents

Abstract

To allow diagnosis of insulation deterioration even for a deterioration pattern not involving a discharge phenomenon and eliminate the need of the application of high voltage to a grounding conductor to make diagnostic operations easy.SOLUTION: An output voltage from a commercial power supply 41 and an output voltage from a superimposing device 42 are applied to a conductor 20a in a power distribution path in a superimposed state. The frequency of an AC voltage output from the superimposing device 42 is determined to be a value obtained by adding a predetermined value Δf to the integral multiple of the commercial power supply 41. A current flowing in an internal insulating body of a connection body 10 to be diagnosed is detected with current transformers CT1-CT3 arranged on a ground path in an aligned direction. A component of the predetermined value Δf is extracted with a filter unit 45c from a result of addition of the currents in the paths performed by an aggregation unit 45a, and a detected current level is compared with one or more thresholds to determine the presence or absence of deterioration and the degree of deterioration with a measurement and diagnosis unit 45d. Even when the superimposing device 42 and a diagnostic device 45 are connected, the grounding conductor does not reach high voltage, and thereby automation of diagnosis and periodic diagnosis are made easy.SELECTED DRAWING: Figure 3

Description

The present invention relates to a connection body deterioration diagnosis device and a connection body deterioration diagnosis method that can be used to detect deterioration of an electrical insulator in a connection body for a high-voltage overhead cable or the like.

For example, commercial AC power supplied to each consumer such as a general household or a factory is generally distributed using a distribution network via a large number of utility poles. In addition, at each utility pole, for example, multiple high-voltage fictitious cables that handle high-voltage power of about 6 kV can be connected to each other, or branches from the high-voltage fictitious cable of the main line and connected to a customer's service line or transformer. It is necessary to connect the branch route. At such a connection point, a high-voltage overhead cable connection body (hereinafter, also simply referred to as a connection body) is used.

The commonly used high-voltage overhead cable connection is a π-type branch connection. In the case of a π-type branch connector, the trunk line of a high-voltage overhead cable is connected to both left and right ends thereof, and the branch line and the pole drop (PD) adapter are connected to the base end. The high-voltage overhead cable connector is used in a state of being installed on a utility pole in a state of being connected to a trunk line, a branch line, or the like of the high-voltage overhead cable in this way.

The connection body is configured by covering the outer circumference of a cylindrical insulator with an aluminum housing. In addition, a plug-in connector plug is provided on the main line terminal of the high-voltage overhead cable, and the insulator has a plug-in connector receipt for connecting (plug-in connection) to this plug-in connector plug inside. Store.

Since the connecting body is constantly exposed to the weather such as wind and rain and the outdoor environment such as a wide range of temperature changes, the internal insulator may be deteriorated due to the influence. When the insulator deteriorates, not only does the connector not function, but also a short circuit or electric shock to the operator is likely to occur, resulting in an electrically dangerous situation. Therefore, it is desirable that the deterioration of the insulator is diagnosed each time and replaced with a new one according to the deterioration status of the insulator.

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

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 any of the high-voltage overhead cable connected to the high-voltage overhead cable connector is acquired, and the commercial power frequency component is removed from the acquired current waveform, and the removed current waveform is obtained. However, the time interval exceeding a predetermined size is measured, and when this time interval is a constant cycle, it is determined that the insulation has deteriorated.

Patent Document 3 shows a technique for reducing the noise of a partial discharge signal to make a determination easily and accurately. Specifically, an electrode is installed on the outside of the high-voltage overhead cable branch connection for power distribution so that the state of partial discharge caused by the insulation deterioration of the high-voltage overhead cable branch connection for power distribution is capacitively coupled to the partial discharge generation part and the electrode. In the method of diagnosing the insulation deterioration state of the high-voltage overhead cable branch connection for power distribution by detecting it as the potential fluctuation signal of the electrode, the noise mixed in the signal is removed by taking the difference between the three phases of the signal. It is characterized by obtaining a partial discharge signal with less noise and diagnosing insulation deterioration. In addition, in the signal for taking the difference, not between the three phases, but between multiple electrodes installed in the high-voltage overhead cable branch connection for distribution and between the high-voltage overhead cable branch connection for distribution of other pillars installed in the same distribution line. Take the difference with.

Patent Document 4 shows a technique for detecting a true deterioration signal due to a water tree and performing a highly accurate diagnosis. Specifically, the AC power supply 5 is connected in the middle of the grounding wire 4 connected between the shielding layer 3a of the power cable 3 to be measured and the grounding. The frequency of the AC power supply 5 is an integral multiple of the commercial frequency ± aHz (0 <a≤10), 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 based on this current. Diagnose the degree of insulation deterioration in the live wire state.

Japanese Unexamined Patent Publication No. 2000-2743 Japanese Unexamined Patent Publication No. 2019-27785 Japanese Unexamined Patent Publication No. 6-123756 Japanese Unexamined Patent Publication No. 9-318696

However, regarding the insulation deterioration of the high-voltage overhead cable connector, a deterioration pattern that does not accompany the discharge phenomenon has also been confirmed. Therefore, it is difficult to improve the diagnostic accuracy of insulation deterioration by the technique of diagnosing insulation deterioration on the premise that electric discharge is generated as in Patent Documents 1 to 3.

Further, the technique of Patent Document 4 is intended for a high-voltage underground cable and can be applied when the ground is in one place, but the shield is grounded in a plurality of places such as a high-voltage overhead distribution line. Not applicable to what has been done. Further, the technique of Patent Document 4 is not intended to be used for diagnosis in which ethylene propylene rubber is used as a connector.

The present invention has been made in view of the above circumstances, and an object of the present invention is to enable diagnosis of insulation deterioration even for a deterioration pattern not accompanied by a discharge phenomenon, and a connection body in which shielding is grounded at a plurality of points. It is an object of the present invention to provide a connection body deterioration diagnosis device and a connection body deterioration diagnosis method, which enable the diagnosis of the connection body.

In order to achieve the above-mentioned object, the connection body deterioration diagnosis device and the connection body deterioration diagnosis method according to the present invention are characterized by the following (1) to (5).
(1) Deterioration of electrical insulation characteristics in a connector having a plurality of connection portions and insulators for connecting a high-voltage cable and to which an AC high voltage of a predetermined frequency is applied is diagnosed in the live-line state of the connector. It is a connector deterioration diagnostic device for
A diagnostic voltage application unit that applies a diagnostic AC voltage having a frequency different from that of the AC high voltage to the conductor of the distribution path including the connector.
A current measuring unit that detects the magnitude of the alternating current flowing through the insulator at at least one location on the distribution path including the connector.
Of the AC current detected by the current measuring unit, the level of the specific frequency component obtained as a result of superimposing the AC high voltage and the diagnostic AC voltage is compared with a predetermined threshold value, and the diagnosis according to the comparison result is performed. The diagnostic unit that outputs the results and
A connected body deterioration diagnostic device.

(2) The current measuring unit detects the alternating current flowing through the insulator at a plurality of points for each of the connectors, and the alternating current detected at the plurality of points is the direction of the current generated by the deterioration of the electrical insulation characteristics. Equipped with an adder that adds in the same state
The diagnostic unit performs a diagnosis based on the addition result of the addition unit.
The connected body deterioration diagnostic device according to (1) above.

(3) 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 diagnostic unit includes a filter for extracting a frequency component corresponding to the predetermined value.
The connection deterioration diagnostic apparatus according to (1) or (2) above.

(4) The diagnostic 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 connection deterioration diagnostic apparatus according to any one of (1) to (3) above.

(5) Deterioration of electrical insulation characteristics in a connector having a plurality of connection portions and insulators for connecting a high-voltage cable and to which an AC high voltage of a predetermined frequency is applied is diagnosed in the live-line state of the connector. It is a connection deterioration diagnosis method for
A procedure for applying a diagnostic AC voltage having a frequency different from that of the AC high voltage to the conductor of the distribution path including the connection body, and
A procedure for detecting the magnitude of alternating current flowing through an insulator at at least one location on a distribution path including the connector, and a procedure for detecting the magnitude of the alternating current flowing through the insulator.
Of the detected AC current flowing through the insulator, the level of the specific frequency component obtained as a result of superimposing the AC high voltage and the diagnostic AC voltage is compared with a predetermined threshold value, and the diagnosis according to the comparison result is performed. The procedure to output the result and
Connection deterioration diagnosis method having.

According to the connector deterioration diagnostic device having the configuration of (1) above, an AC high voltage having a predetermined frequency and a diagnostic AC generated by a diagnostic voltage application unit are generated with respect to the conductor in the distribution path in the live-line state of the connector. It is applied at the same time with the voltage superimposed. As a result, the AC current flowing through the insulator can be detected as a specific frequency component whose frequency is significantly different from that of the AC high voltage. By comparing the level of this alternating current with a predetermined threshold value, insulation deterioration can be diagnosed. Moreover, since it is not necessary to apply a special voltage to the ground wire, problems such as electric shock are less likely to occur, and diagnostic work can be easily performed.

According to the connector deterioration diagnostic device having the configuration of (2) above, even in a situation where the current flowing on the insulator is divided into a plurality of different paths due to the deterioration of the specific insulator to be diagnosed. Highly accurate insulation characteristic diagnosis becomes possible. That is, by adding the alternating currents detected at a plurality of locations in a state where the directions of the currents generated by the deterioration of the electrical insulation characteristics are aligned, the deterioration of the electrical insulation characteristics can be correctly evaluated for the entire insulator. It also makes it possible to reduce the effect of current flowing through another insulator that is not the subject of diagnosis.

According to the connector deterioration diagnostic apparatus having the configuration of (3) 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 a predetermined value to a value 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 connected body deterioration diagnostic device having the configuration of (4) above, it is possible to determine not only the presence or absence of deterioration but also the degree of deterioration by using a plurality of threshold values.

According to the connection body deterioration diagnosis method having the configuration of (5) above, an AC high voltage having a predetermined frequency and a diagnostic AC generated by a diagnostic voltage application unit are generated with respect to the conductor in the distribution path in the live-line state of the connection body. It is applied at the same time with the voltage superimposed. As a result, the AC current flowing through the insulator can be detected as a specific frequency component whose frequency is significantly different from that of the AC high voltage. By comparing the level of this alternating current with a predetermined threshold value, insulation deterioration can be diagnosed.

According to the connection body deterioration diagnosis device and the connection body deterioration diagnosis method of the present invention, it is possible to diagnose insulation deterioration even for a deterioration pattern not accompanied by a discharge phenomenon.

The present invention has been briefly described above. Further, the details of the present invention will be further clarified by reading through the embodiments described below (hereinafter referred to as "embodiments") with reference to the accompanying drawings. ..

FIG. 1 is a vertical cross-sectional view showing a configuration example of one connector. FIG. 2 is a front view showing a configuration example of a high-voltage overhead cable end. FIG. 3 is a block diagram showing a connection state between one connection body and the connection body 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 connector deterioration diagnostic apparatus.

Specific embodiments of the present invention will be described below with reference to the respective figures.

<Explanation of the connection target for diagnosis and high-voltage fictitious cable>
FIG. 1 shows a configuration example of one connection body 10. Further, FIG. 2 shows a configuration example of the end of the high-voltage overhead cable 20 connected to the connection body 10. The connection body 10 shown in FIG. 1 is a connection body for a high-voltage overhead cable, and is used for electrically connecting 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 ordinary households, for example, as a sinusoidal AC voltage of several kV, via a distribution path including a high-voltage overhead cable 20. Supply commercial power. Since it is necessary to distribute power over a long distance, this distribution path usually includes a large number of utility poles supporting the high voltage overhead cable 20. 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 at each utility pole. Further, at each utility pole, it is necessary to connect one or a plurality of branch lines to the main line of the distribution path and supply electric power from this branch line to the path of each consumer or the like. A connecting body 10 is used to connect this branch line. Therefore, the connecting body 10 is often configured in a π shape as in the example shown in FIG.

An important function required of the connection body 10 is electrical insulation. That is, if the high-voltage current flowing through the high-voltage overhead cable 20 is not prevented from flowing to a portion other than the required portion at each utility pole, an accident may occur in which an operator or the like gets an electric shock, so that electrical insulation is required. Therefore, an insulator is provided in the connecting body 10 as described below.
In FIG. 1, the outer periphery of the actual connecting body 10 is covered with an aluminum housing, but the cross section of the housing is omitted in order to make the structure of the connecting body easy to understand.

As shown in FIG. 1, the connecting body 10 is used to mediate and connect high-voltage overhead cables (see FIG. 2) 20 for transmitting commercial power. 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), semi-conductive EP rubber, or the like, and is configured to include a tubular insulator 11 arranged inside the connecting body 10. .. The insulator is provided in a three-layer structure. Specifically, an insulating layer made of EP rubber is centrally arranged as a base layer, and inside this insulating layer is an internal semi-conductive material made of semi-conductive EP rubber. A layer is arranged, and an external semi-conductive layer made of semi-conductive EP rubber is arranged outside the insulating layer. That is, the insulating layer of the insulator 11 is provided so as to be sandwiched between the semi-conductive layers from both sides in the radial direction.

Further, the outer circumference of the insulator 11 is covered with the aluminum housing 14 in a state where the insulator 11 is in electrical contact with the aluminum housing 14 by the external semi-conductive layer. The aluminum housing 14 electrically functions as a shielding layer. Further, a part of the insulating layer of the insulator 11 is provided so as to be exposed to the outside of the connecting body 10, and the voltage detection terminal portion 12 is provided in this exposed portion. Then, the voltage detection terminal portion 12 is covered with a voltage detection terminal cap 13 made of semi-conductive EP rubber.

Further, the connecting body 10 and the insulating body 11 are formed in a π shape in outer shape. Then, trunk line connecting portions 15 for connecting to each high-voltage overhead cable 20 of the trunk line are arranged at both left and right ends of the insulator 11. Further, branch connection portions 16 for connecting to the high-voltage overhead cable 20 of the branch line are arranged at each pair of base ends of the insulator 11.

Further, in order to enable the connection terminal 21 provided at the end of the high-voltage overhead cable 20 to be connected by a plug-in type, a plug-in connector recess (not shown) is incorporated in the trunk line connection portion 15 and the branch connection portion 16. The plug-in connector Resep is surrounded by an insulator. Further, the plug-in connector / receipt is integrally provided as a conductor from a copper alloy material having excellent electrical conductivity.
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 portion 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. The connection terminal 21 has a plug-in connector plug 22, a waterproof cylinder 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 / receipt of the connecting body 10. The waterproof cylinder 24 is arranged at the base end of the connection terminal 21 and is made of semi-conductive EP rubber for electrically connecting to the shielding layer of the high-voltage overhead cable 20. The spacer is arranged between the plug-in connector plug 22 and the waterproof cylinder 24, and has a function of insulating the conductor including the plug-in connector plug 22 and the shielding layer including the waterproof cylinder 24.

The plug-in connector plug 22 is provided so that it can be easily inserted and compressed and connected to the plug-in connector / receipt of the trunk line connection portion 15 and the branch connection portion 16 of the connection body 10. Further, the waterproof cylinder 24 is electrically connected by coming into contact with the external semi-conductive layer of the connecting body 10.
As with the connection body 10, the outer circumference of the connection terminal 21 of the high-voltage overhead cable 20 is covered with the housing 26.

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

The connection body 10 configured as described above is supported by a gantry installed on each utility pole. Therefore, the connecting body 10 is used in an environment that is constantly exposed to an outdoor environment such as wind and rain weather and a wide range of temperature changes. Further, the insulator 11 is constantly exposed to electrical stress. Therefore, the insulator 11 inside the connecting body 10 may be deteriorated due to the influence of the weather, electrical stress, or the like, and if the deterioration is progressing, it is necessary to replace the connecting body 10. However, the replacement involves a power outage in the distribution system. Therefore, it is desirable to systematically execute the power failure work and the replacement work according to the deterioration state of the insulator 11 to minimize the influence on the home and the electricity demand facility. That is, it is required that the deterioration state of the insulator 11 inside the connecting body 10 is highly versatile and can be accurately grasped in advance.
The connection body deterioration diagnosis device 30 described below can be used for diagnosing the deterioration status of the insulator 11 arranged inside the connection body 10.

<Configuration example of connection body and connection body deterioration diagnosis device>
FIG. 3 shows an example of the connection state between one connection body 10 and the connection body deterioration diagnosis device 30.
The connector deterioration diagnostic device 30 in the present embodiment includes a superimposition device 42 and a diagnostic device 45. In the example shown in FIG. 3, the connection body 10 is the diagnosis target of the connection body deterioration diagnosis device 30. The superimposing device 42 has a function of superimposing a special AC voltage for diagnosis on the AC voltage on the distribution line 44. The diagnostic device 45 has a function of detecting currents of a plurality of paths flowing through the insulator of the connector 10 as currents i1, i2, and i3 to diagnose 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 supply 41, the frequency f1 of the diagnostic AC voltage generated by the superimposing device 42 is determined by, for example, the following equation.
f1 = 2 ・ f0 + Δf
Δf: A constant sufficiently smaller than f0 (for example, 5 Hz)

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

In order to superimpose such a diagnostic AC voltage, the superimposing device 42 is connected in parallel with the commercial power supply 41. Further, inside the superimposing device 42, an isolation transformer 42b and a coupling capacitor 42c are provided in addition to the diagnostic AC power supply 42a. The 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 ground 43. One end of the secondary winding of the isolation transformer 42b is connected to the commercial power supply 41 and the distribution line 44 via the coupling capacitor 42c, and the other end is connected to the commercial power supply 41 and the ground 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 the high voltage. It is assumed that the winding number 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 superposed on the output of the commercial power supply 41.

The capacitance of the coupling capacitor 42c is determined so that the impedance with respect to the frequency (f1) of 105 Hz is relatively small and the impedance with respect to the frequency (f0) of 50 Hz 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 distribution line 44.

The diagnostic device 45 includes an aggregation unit 45a, a current detection unit 45b, a filter unit 45c, and a measurement / diagnosis unit 45d.
The collecting unit 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 detecting unit 45b, and has a function for adding the currents i1, i2, and i3 of each path. Have.

The currents i1, i2, and i3 are current signals indicating the measured values of the current transformers CT1, CT2, and CT3, respectively. The current transformers CT1, CT2, and CT3 each output a positive current in the forward direction of the current direction in each path generated when the insulator to be measured is deteriorated. It is clamped to each current path in the same direction. That is, when the insulator of the connection body 10 to be measured is deteriorated, the currents i1, i2, and i3 flow in the direction of flowing from the lead wires 46, 47, and 48 toward the collecting portion 45a. Therefore, the currents i1, i2, and i3 can be added in a state where the polarities are aligned at the collecting portion 45a.

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

The present inventor has a high correlation between the current of a specific frequency component (Δf) obtained by superimposing the diagnostic AC voltage (f1) with the insulation resistance of the insulator in the connector 10, that is, deterioration. It has been clarified by the experiment of. Therefore, only the signal having a high correlation with the deterioration of the insulator in the connecting body 10 can be extracted by the filter unit 45c.

The measurement / diagnosis unit 45d compares the level of the signal component extracted by the filter unit 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 and the degree of deterioration of the insulator in the connector 10. Perform the process for diagnosis. The details will be described later.

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

Further, a messenger wire 32 provided to prevent an excessive 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 a gantry 31. It is connected. Similarly, a messenger wire 33 provided to prevent excessive 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 a gantry 31. Is connected to. The messenger wires 32 and 33 are made of steel and are conductors, respectively.

The high-voltage overhead cables 20-1 and 20-2 are composed of a conductor 20a, an insulator 20b, a shielding copper tape 20c, and a sheath 20d, respectively. That is, the outer periphery of the conductor 20a, which is the core wire, is covered with the insulator 20b, the outside of the insulator 20b is covered with the shielding copper tape 20c, and the outside of the shielding copper tape 20c is formed as a sheath 20d, that is, a cable covered with an outer skin. Has been done.

The conductor 20a of the high-voltage overhead cable 20-1 near the power supply side is connected to the commercial power supply 41 via an equivalent distribution line 44. Further, since the superimposition device 42 is connected to the distribution wire 44, the AC voltage (50 Hz) output by the commercial power supply 41 and the diagnostic output of the superimposition device 42 when the connector deterioration diagnosis device 30 is operating. Is applied to the conductor 20a of the high-voltage overhead cable 20-1 in a state where the AC voltage (105 Hz) of the above is superimposed. Further, 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 superposed on the conductor 20a of the high-voltage overhead cable 20-2.

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

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

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

The current transformer CT1 of the connection body deterioration diagnosis device 30 is clamped so as to surround the outer periphery of the messenger wire 32, and detects a current flowing out from the connection body 10 and the gantry 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 so as to surround the outer periphery of the ground wire GL2, and the current in the direction in which the current passing through the ground wire GL2 flows out from the connection body 10 and the gantry 31 toward the grounding point GP2 is detected. In some cases, the current transformer CT2 is clamped in a direction in which the signal becomes positive. The current transformer CT3 is clamped so as to surround the outer periphery of the messenger wire 33, and when the current in the direction flowing out from the connecting body 10 and the gantry 31 to the messenger wire 33 is detected, the signal becomes positive. The current transformer CT3 is clamped in the direction.

When the insulator in the connection body 10 is deteriorated, the conductor 20a of the high-voltage overhead cable 20-1 and the conductor in the connection body 10 pass through the deteriorated insulator when the potential is positive. , The current flows in the direction of flowing out toward the ground 43.

Typical examples of this current are the current I1 flowing from the insulator in the connection body 10 to the ground 43 through the gantry 31 and the messenger wire 32, and the insulation in the connection body 10 through the gantry 31 and the ground wire GL2. It is assumed that the current I2 flows through the ground 43 and the current I3 flows from the insulator in the connecting body 10 to the ground 43 through the gantry 31 and the messenger wire 33.

The current transformer CT1 detects the current I1 as the current i1. The current transformer CT2 detects the current I2 as the current i2. The current transformer CT3 detects the current I3 as the current i3. Since the collecting portion 45a in the diagnostic apparatus 45 outputs the result of adding all the currents i1 to i3 (I1 to I3), the diagnostic apparatus 45 outputs the current generated by the deterioration of the insulator in the connecting body 10. The magnitude can be evaluated as the sum of the currents passing through various paths.

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

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

Similar to the configuration of FIG. 3, the conductor 20a of the high-voltage overhead cable 20-1 connected to one end of the connecting body 10-1 in FIG. 4 is connected to the commercial power supply 41 and the superimposing 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 the connector 10-1. The current transformer CT11 is clamped so as to surround the outer periphery of the messenger wire 32-1 and signals the current when the current in the direction from the connecting body 10-1 and the gantry 31-1 toward the messenger wire 32-1 is detected. The current transformer CT11 is clamped in the direction in which the current transformer becomes positive.

Further, the current transformer CT12 is clamped so as to surround the outer periphery of the grounding wire GL12, and when the current in the direction flowing from the connecting body 10-1 and the gantry 31-1 through the grounding wire GL12 to the ground 43 is detected. The current transformer CT12 is clamped in the direction in which the signal becomes positive. The current transformer CT13 is clamped so as to surround the outer periphery of the messenger wire 32-2, and when the current in the direction from the connecting body 10-1 and the gantry 31-1 to the messenger wire 32-2 is detected, the signal is detected. The current transformer CT13 is clamped in the direction in which the current transformer becomes positive.

Similar to the above, current transformers CT21, CT22, and CT23 are provided to enable detection of insulation deterioration in the connector 10-2. The current transformer CT21 is clamped so as to surround the outer periphery of the messenger wire 32-2, and when the current in the direction from the connecting body 10-2 and the gantry 31-2 to the messenger wire 32-2 is detected, the signal is detected. The current transformer CT21 is clamped in the direction in which the current transformer becomes positive.

Further, the current transformer CT22 is clamped so as to surround the outer periphery of the grounding wire GL22, and when the current in the direction flowing from the connecting body 10-2 and the gantry 31-2 through the grounding wire GL22 to the ground 43 is detected. The current transformer CT22 is clamped in a direction in which the signal becomes positive. The current transformer CT23 is clamped so as to surround the outer periphery of the messenger wire 32-3, and when the current in the direction from the connecting body 10-2 and the gantry 31-2 to the messenger wire 32-3 is detected, the signal is detected. The current transformer CT23 is clamped in the direction in which the current transformer becomes positive.

The outputs of the current transformers CT11, CT12, and CT13 are connected to the collecting portion 45a-1 of the diagnostic apparatus 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 portion 45a-2 of the diagnostic apparatus 45 via the lead wires 46-2, 47-2, and 48-2, respectively.

In the example of FIG. 4, the collecting unit 45a-1 is connected to the input of the current detection unit 45b-1, and the collecting unit 45a-2 is connected to the input of the current detection unit 45b-2. When a plurality of connecting bodies 10-1 and 10-2 are to be diagnosed as shown in FIG. 4, a plurality of current detecting units 45b-1 are contained in one diagnostic device 45 shown in FIG. 45b-2 may be equipped so that one of them can be selectively used, or a plurality of collecting units 45a-1 and 45a-2 may be selectively used by a switch or the like to selectively use one of the current detecting units 45b. It may be configured to connect to the input.

In FIG. 4, assuming that the insulator is deteriorated at the deterioration point Px near the center of the connector 10-2 and the other connectors 10-1 and 10-3 are not deteriorated, the deteriorated insulator is used. The flowing current flows in the path shown by each arrow shown in FIG.

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

Here, the directions of the currents of the three current paths are aligned in the direction of flowing out from the connecting body 10-2 toward the outside. Therefore, the current detection levels detected by the current transformers CT21, CT22, and CT-23 are added as signals of the same polarity at the collecting unit 45a-2, so that the insulator of the connector 10-2 deteriorates. If this is the case, the output level of the current detection unit 45b-2 will increase. By discriminating the magnitude of this level, the diagnostic apparatus 45 can detect the deterioration of the insulator of the connecting body 10-2.

On the other hand, there is also a current path that flows from the connecting body 10-2 and the gantry 31-2 to the adjacent pedestal 31-1 side via the messenger wire 32-2. The current of this path is further divided into a current path that further branches and flows to the ground 43 via the ground wire GL2 and a current path that flows to the ground 43 via the messenger wire 32-1 and the ground wire GL11.

Therefore, the current flowing due to the deterioration of the insulator of the connecting body 10-2 is also detected by 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 in which the current flows from the messenger wire 32-2 toward the gantry 31-1, and has the opposite polarity (negative electrode property) from the usual direction. 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 connection body 10-2 side to the connection body 10-1 side, each signal of the positive current transformers CT11 and CT12. And when the signal of the negative electrode current transformer CT13 is added by the collecting portion 45a-1, the levels having different polarities are canceled out. That is, the level of the current detected by the collecting portion 45a-1 is significantly reduced as compared with the level of the current detected by the collecting portion 45a-2. Therefore, the deterioration of the connecting body 10-1 and the deterioration of the connecting body 10-2 can be reliably distinguished by the difference in the current levels in the plurality of collecting portions 45a-1 and 45a-2 having different positions from each other.

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

The operation shown in FIG. 5 is generally assumed to be repeatedly executed periodically using a computer, but the same operation can be realized by manual operation and judgment by the operator. be. The operation of FIG. 5 assuming a case of being controlled by a computer will be described below.

In the first step S11 of FIG. 5, the computer switches the operation of the diagnostic AC power supply 42a on. Since the commercial power supply 41 constantly supplies commercial AC power, as a result of executing S11, the 105 Hz diagnostic AC voltage output by the superimposing device 42 is applied to the distribution line 44 in a state of being superimposed on the 50 Hz commercial AC power. Will be done. Then, an AC voltage obtained by superimposing a commercial AC power of 50 Hz and a diagnostic AC voltage of 105 Hz 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 the superimposed frequency component Δf (for example, 5 Hz) having a high correlation with the deterioration of the insulator in the connector 10-1. That is, after the current (i1 + i2 + i3) added by the collecting unit 45a is converted into a voltage by the current detection unit 45b, the superimposed frequency component Δf is extracted by the filter unit 45c, and the voltage is specified by the measurement / diagnosis unit 45d. , The AC superimposed current of Δf flowing through the insulator of the connector 10-1 is grasped.

The computer compares the level of the AC superimposed current of Δf measured in S12 with the plurality of threshold values Th1 to Th3, respectively (S13, S15, S17). Then, when the level of the AC superimposed current is smaller than the first threshold value Th1, the process proceeds to S14, when the level is smaller than the second threshold value Th2, the process proceeds to S16, and when the level is smaller than the third threshold value Th3, the process proceeds to S18. If the threshold value is Th3 or higher, the process proceeds to S19.

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

Further, when the computer executes step S16, the detected AC superimposed current of Δf is relatively small, so that the computer recognizes that the degree of deterioration of the insulator in the connector 10-1 to be diagnosed is small, and the recognition result. Is displayed as a message of numerical values or characters, for example.

When the computer executes step S18, the detected alternating current superimposed current of Δf is moderately large, so that the computer recognizes that the insulator in the connector 10-1 to be diagnosed is moderately deteriorated. The recognition result is displayed as a message of numerical values or characters, for example.

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

For example, as in the example shown in FIG. 4, when the insulator is deteriorated at the deterioration point Px on the connecting body 10-2, when the diagnostic device 45 measures the current of the collecting portion 45a-2, it becomes Δf. Since the AC superimposed current becomes large, S17 in FIG. 5 is executed, and the computer recognizes the deterioration of the connection body 10-2. On the other hand, when the diagnostic apparatus 45 measures the current of the collecting unit 45a-1, the added current value decreases due to the difference in the polarity of the currents of the plurality of paths. Therefore, for example, S14 or S16 in FIG. 5 is executed and the computer is executed. Therefore, it is recognized that the deterioration of the insulator in the connecting body 10-1 is small.

<Advantages of Connection Deterioration Diagnostic Device 30>
In the connector deterioration diagnostic 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. .. Further, by appropriately determining the frequency f1 (for example, 105 Hz) of the diagnostic AC power supply 42a with respect to the frequency f0 (for example, 50 Hz) of the commercial power supply 41, a specific frequency component Δf useful for diagnosing the deterioration of the insulator in the connector 10. (Eg 5 Hz) can be generated. The present inventor has confirmed by experiments that the frequency component Δf of the current flowing through the insulator inside the connector 10 has a high correlation with the insulation resistance of the connector 10. Therefore, deterioration of the connecting body 10 without discharge can also be detected by the magnitude of 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, since the filter unit 45c extracts the frequency component Δf, the measurement / diagnostic unit 45d discriminates the magnitude of the level of the frequency component Δf of the current flowing through the insulator inside the connector 10. can.

Moreover, the diagnosis can be performed without applying a special voltage to each of the ground wires GL1, GL2, and GL3. Therefore, even if the worker or the like touches the ground wires GL1, GL2, GL3, etc. at the time of diagnosis, there is no concern of electric shock. Further, since the superimposing device 42 and the diagnostic device 45 can be always connected, the diagnosis can be automated and it is easy to carry out the diagnosis on a regular basis.

Further, even when the current flowing through the insulator inside the connecting body 10 is divided into a plurality of paths and flows, the currents of the respective paths are detected by the plurality of current transformers CT1 to CT3 as shown in FIG. By adding the plurality of outputs at the collecting unit 45a, a current having a high level of correlation with the degree of insulation deterioration can be obtained.

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

Further, with respect to the deterioration of the insulator in the connector 10, the direction of the current flowing through the insulator is taken into consideration, and the polarities with respect to the direction of the current detected by the plurality of current transformers CT1 to CT3 are aligned in the collecting portion 45a. By adding, it becomes possible to improve the diagnostic accuracy of deterioration. In particular, as shown in FIG. 4, in a situation where a plurality of connecting bodies 10-1, 10-2, 10-3, ... Are connected in series, each position of the collecting portions 45a-1, 45a-2 Since different current levels are detected, it is possible to distinguish between the deteriorated connection body 10-2 and the non-deteriorated connection body 10-1.

The connection body 10 to be diagnosed by the connection body deterioration diagnosis device 30 is not limited to the π type, and can correspond to various types of connections. Further, the application of the connection body deterioration diagnosis device 30 is not limited to the connection body 10 of the high-voltage overhead cable 20, but can be applied to the connection body of various distribution paths.

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

[2] The current measuring unit detects the alternating current flowing through the insulator at a plurality of points for each of the connectors, and the alternating current detected at the plurality of points is the direction of the current generated by the deterioration of the electrical insulation characteristics. It is provided with an addition unit (aggregation unit 45a-1, 45a-2) for adding in a state where the currents are aligned.
The diagnostic unit performs a diagnosis based on the addition result of the addition unit.
The connected body deterioration diagnostic device according to the above [1].

[3] The frequency (f1) of the AC voltage for diagnosis 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 diagnostic unit includes a filter (filter unit 45c) for extracting a frequency component (Δf) corresponding to the predetermined value.
The connection deterioration diagnostic apparatus according to the above [1] or [2].

[4] The diagnostic 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 determine the degree of deterioration (S13). ~ S19),
The connection deterioration diagnostic apparatus according to any one of the above [1] to [3].

[5] Deterioration of electrical insulation characteristics in a connector having a plurality of connection portions and insulators for connecting a high-voltage cable and to which an AC high voltage of a predetermined frequency is applied is diagnosed in the live-line state of the connector. It is a connection deterioration diagnosis method for
The procedure (S11) of applying a diagnostic AC voltage having a frequency different from that of the AC high voltage to the conductor of the distribution path including the connector.
A procedure (S12) for detecting the magnitude of the alternating current flowing through the insulator at at least one location on the distribution path including the connector.
Of the detected AC current flowing through the insulator, the level of the specific frequency component obtained as a result of superimposing the AC high voltage and the diagnostic AC voltage is compared with a predetermined threshold value, and the diagnosis according to the comparison result is performed. Procedures for outputting the results (S13 to S19) and
Connection deterioration diagnosis method having.

10,10-1,10-2,10-3 Connection 11 Insulator 12 Power detection terminal 13 Power detection terminal cap 14 Housing 15 Trunk connection 16 Branch connection 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 cylinder 25 Grounding wire terminal 26 Housing 30 Current transformer deterioration diagnostic device 31, 31 -1,31-2,31-3 Stand 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 Ground 44 Distribution wire 45 Diagnostic device 45a Assembly part 45b Current detection part 45c Filter part 45d Measurement / diagnosis part 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 (5)

A connection that has a plurality of connections and insulators for connecting high-voltage cables, and is used to diagnose deterioration of electrical insulation characteristics in a connector to which an AC high voltage of a predetermined frequency is applied in the live-line state of the connector. It is a body deterioration diagnostic device,
A diagnostic voltage application unit that applies a diagnostic AC voltage having a frequency different from that of the AC high voltage to the conductor of the distribution path including the connector.
A current measuring unit that detects the magnitude of the alternating current flowing through the insulator at at least one location on the distribution path including the connector.
Of the AC current detected by the current measuring unit, the level of the specific frequency component obtained as a result of superimposing the AC high voltage and the diagnostic AC voltage is compared with a predetermined threshold value, and the diagnosis according to the comparison result is performed. The diagnostic unit that outputs the results and
A connected body deterioration diagnostic device. The current measuring unit detects the alternating current flowing through the insulator at a plurality of points for each of the connectors, and aligns the directions of the alternating currents detected at the plurality of points with the current generated due to the deterioration of the electrical insulation characteristics. Equipped with an adder that adds in the state
The diagnostic unit performs a diagnosis based on the addition result of the addition unit.
The connector deterioration diagnostic apparatus according to claim 1. 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 diagnostic unit includes a filter for extracting a frequency component corresponding to the predetermined value.
The connection deterioration diagnostic apparatus according to claim 1 or 2. The diagnostic 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 connection deterioration diagnostic apparatus according to any one of claims 1 to 3. A connection that has a plurality of connections and insulators for connecting high-voltage cables, and is used to diagnose deterioration of electrical insulation characteristics in a connector to which an AC high voltage of a predetermined frequency is applied in the live-line state of the connector. It is a method for diagnosing deterioration of the body.
A procedure for applying a diagnostic AC voltage having a frequency different from that of the AC high voltage to the conductor of the distribution path including the connection body, and
A procedure for detecting the magnitude of alternating current flowing through an insulator at at least one location on a distribution path including the connector, and a procedure for detecting the magnitude of the alternating current flowing through the insulator.
Of the detected AC current flowing through the insulator, the level of the specific frequency component obtained as a result of superimposing the AC high voltage and the diagnostic AC voltage is compared with a predetermined threshold value, and the diagnosis according to the comparison result is performed. The procedure to output the result and
Connection deterioration diagnosis method having.

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