JP3316182B2 - Method for estimating remaining life of coated cable - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for diagnosing deterioration of a coated cable, a method for extending a service life, and a method for estimating a remaining service life.

[0002]

2. Description of the Related Art There is a problem that a covering material of a cable laid, particularly a surface covering material such as a sheath, changes with time due to various factors, thereby deteriorating mechanical properties and electrical insulation and causing a dielectric breakdown of the cable. It is necessary to inspect it periodically to diagnose the deterioration state. For this purpose, various methods of diagnosing deterioration have been proposed in the past, for example, a method of diagnosing a state of deterioration from a change in the ultrasonic wave propagation characteristics of a coating material (Japanese Patent Laid-Open No. 7-1995)
JP-A-35732, JP-A-7-35733, etc., and a method of diagnosing a deterioration state from a change in surface rebound hardness of a coating material (JP-B-1-20370, JP-A-8-3)
No. 13423).

[0003] Conventionally, the installation environment of a covered cable generally differs in the longitudinal direction of the covered cable, and therefore, the degree of deterioration of the covered cable varies in the longitudinal direction. In addition, breakage of the coated cable due to environmental degradation usually occurs at a site where the degradation progresses quickly. Therefore, despite the fact that the deterioration diagnosis of the insulated cable should be performed at a site where the deterioration progresses quickly, conventionally, the deterioration diagnosis is performed on an appropriate site without any care in selecting the deterioration diagnosis site. In addition, there is often a discrepancy between the expected life of the coated cable obtained from the deterioration diagnosis and the actual life (such as insulation breakdown of the cable at a portion where deterioration progresses quickly). In other words, the conventional method has a problem in grasping the actual condition of the deterioration of the coated cable.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a deterioration diagnosis system capable of more accurately grasping the actual state of deterioration of a covered cable in view of the above. Another object of the present invention is to provide a method capable of extending the life of a coated cable after deterioration diagnosis and a method of estimating the remaining life of the coated cable.

[0005]

The above-mentioned objects can be solved by the following methods. (1) A coating having a coating layer formed of an organic polymer material
Forming a coating layer to estimate the remaining life of a covered cable
Organic polymer material itself has the same composition as the organic polymer material
From a reproducible material with or a material similar to the reproducible material
At least one material selected from the group consisting of
Ultrasonic propagation characteristics Vts at reference temperature ts or degradation diagnosis characteristics
Between the heating temperature t and the heating time h using the property as a parameter
A process α for experimentally establishing a relationship (th-h correlation);
At least one arbitrarily selected from the tha correlations.
The ht correlation with respect to the parameter value is expressed as the life tha phase.
The process β defined as the relationship and the remaining life laid for a certain period
Organic fractions forming the coating layer of the coated cable for life estimation
The value of the ultrasonic propagation characteristic Vts or the degradation diagnostic characteristic of the
Obtaining step γ and the covering
-Life correlation at average temperature of cable coating layer
Ultrasonic propagation characteristics obtained in the above heating time h1 and process γ
About Vts or the value (parameter value) of the deterioration diagnosis characteristic
Obtaining a heating time h2 on the tha correlation of
The coating time has a time difference between the heating time h1 and the heating time h2.
And a process ε for making the remaining life of the cable
Method for estimating the remaining life of coated cables. (2) The sheathed cable is in at least one section thereof
Strength of cable deterioration factor in the longitudinal direction of the cable
Multiple deterioration factor measurement means so that the distribution of
From the measurement by multiple deterioration factor measuring means.
The part where the strength of the deterioration factor in the longitudinal direction of the
At least according to the value of the deterioration diagnosis characteristic of that part.
The coated cable according to the above (1), which has been diagnosed.
Method for estimating the remaining life of (3) The deterioration factor measuring means determines the temperature and the coating of the coated cable.
Whether or not the cable is immersed in water,
PH of immersion water, presence of oil on coated cable, air
Humidity, atmospheric hydrogen sulfide concentration, atmospheric oxygen concentration,
Atmospheric radiation dose, solar radiation, coated cable after installation
Of cable , vibration applied to the coated cable after installation
At least one item selected from the group consisting of
And / or can be detected as described in (2) above.
Method for estimating remaining life of coated cable. (4) The heating temperature t in the tha correlation is the absolute temperature
The heating time h is the logarithm of the heating time.
The remainder of the coated cable according to any one of the above (1) to (3)
Life estimation method. (5) Deterioration diagnostic characteristics form the coating layer of the coated cable
Strength, elongation at break, modulus of elasticity,
Modulus, modulus, permittivity, dielectric loss tangent, volume resistivity,
AC breakdown voltage strength, impulse breakdown voltage strength, ultrasonic transmission
Transport characteristics, surface rebound hardness, surface penetration hardness,
Consists of torsional torque and bending stiffness of insulated cable
The above (1) to which are at least one item selected from the group
Method for estimating remaining life of coated cable according to any of (4)
Law.

[0006]

By disposing a plurality of deterioration factor measuring means along the laid cable, the distribution of the strength of the deterioration factor in the longitudinal direction of the coated cable can be grasped. Deterioration factors of the coated cable, for example, a part where the temperature is particularly high or a part where the amount of solar radiation or radiation is particularly large, generally show that deterioration progresses faster than others, and correct the part that seems to progress faster. You can know. If the strength of the degradation factor is known correctly, the degree of degradation of the coated cable at that location can be determined by the degradation diagnostic properties, such as the tensile strength of the organic polymer material forming the coating layer and the elongation at break.
Can be diagnosed from the value of On the other hand, knowing a part where the strength of the deterioration factor is strong, and diagnosing the degree of deterioration of that part and confirming that deterioration has progressed quickly, by improving the environment of that part, for example, the temperature of the coated cable becomes particularly low. By shifting the installation position of a high portion or lowering the cable temperature by another appropriate method, it is possible to delay the progress of the deterioration of the coated cable and extend the service life. Further, using the tha correlation established in the process α of the invention of (5), the process is performed based on the expected or artificially determined average temperature of the coating layer of the coated cable after the installation for a certain period. The remaining life of the coated cable can be estimated by the method described below using ε.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

In the present invention, all sections of the laid covered cable may be subjected to the deterioration diagnosis. However, depending on the laying conditions, only certain sections are particularly susceptible to deterioration. In such a case, the deterioration factor measuring means can be installed only in the certain section and can be used as a diagnosis target.

The deterioration factor measuring means is installed in the longitudinal direction along the laid cable. As the deterioration factors in the present invention, various factors that deteriorate the coated cable can be targeted. Typical examples are temperature, humidity and water, pH of water, oil, hydrogen sulfide, oxygen,
Ozone or other reactive gases, sunlight, radiation, etc., which chemically degrades the material of the coating layer of the coated cable, or causes strain at the various parts of the coated cable or vibration caused by external force, etc. And those that mechanically degrade.

Among the means for measuring the deterioration factors are the temperature of the coated cable, whether or not the coated cable is immersed in water, the pH of the immersion water when the coated cable is immersed in water, whether or not oil has adhered to the coated cable, and the humidity in the atmosphere. , The concentration of hydrogen sulfide in the atmosphere,
Measurement and / or detection of at least one item selected from the group consisting of oxygen concentration in the atmosphere, radiation dose in the atmosphere, insolation, strain of the covered cable after installation, and vibration applied to the covered cable after installation ( Hereinafter, measurement and detection are collectively referred to simply as measurement.)

The intervals at which the deterioration factor measuring means are installed differ somewhat depending on the type of the deterioration factor to be measured, the installation condition of the covered cable, and the environment. For example, the radiation dose in a well-ventilated outdoor environment, the concentration of reactive gas such as hydrogen sulfide, oxygen, and ozone in the atmosphere, the humidity, the amount of solar radiation, and the like are substantially constant over a relatively wide range. An interval is sufficient. On the other hand, since the radiation dose received by the coated cable laid in the nuclear power plant, the immersion of the coated cable laid on the road in the production plant in water and the adhesion of oil occur in a relatively narrow range, about 1 to 10 m, and in some cases, 0.5 ~
It is preferable to install them at intervals of about 2 m. In short, the determination may be made in consideration of the width of the range in which the degradation factors to be measured are considered to be substantially the same. The installation interval is generally 0.5
It is about 50 m, especially about 1-10 m.

Next, an example of a method of installing each deterioration factor measuring means will be described. The means for measuring the temperature of the covered cable may be installed using an adhesive tape or the like so that the temperature-sensitive portion contacts the surface of the covered cable.

The humidity in the atmosphere, the concentration of hydrogen sulfide, the concentration of oxygen,
Each of the means for measuring the amount of solar radiation or radiation dose has its sensing part in contact with or near the coated cable, for example, 1 to 50 c from the surface of the coated cable.
It may be installed by an arbitrary method in the atmosphere about m away.

Each of the means for measuring the presence or absence of underwater immersion of the coated cable and the pH of the immersion water in the case of immersion in water are immersed in water so that the sensing portion thereof comes into contact with the lower surface to the middle surface of the coated cable. It should be installed so that it can freely come into direct contact with water when it is done.

As means for measuring the presence or absence of oil adhesion of the coated cable, for example, a method in which a rubber having a rubber whose electric resistance value changes by swelling with oil in a sensing portion is exemplified. And preferably in contact with the surface of the coated cable.

After the cable is laid, the sheathed cable expands and contracts due to a temperature change due to the suspension of the cable itself, a temperature change of a cable support used for laying the sheathed cable, deformation due to an external force, or a change in the sheathed cable itself. Such an external force causes various types of distortion (deformation) such as elastic distortion and permanent distortion (plastic deformation). For example, torsion or bending of the entire covered cable or deformation of the cross-sectional shape of the covering layer. The measurement of the strain of the coated cable in the present invention may be performed for any one or more of such strains.For example, regarding the deformation of the cross-sectional shape of the coating layer, a strain gauge capable of measuring a change in the outer diameter of the cable is used for the cable. It can be measured by placing it in

[0017] Vibration occurring at the place where the covered cable is laid, for example, vibration of the ground due to long-term civil engineering work near the place where the covered cable is laid, vibration of the building itself when the laid place is inside the building, and covered cable for movement With regard to the above, the whole or a part of the coated cable may vibrate due to vibration of the cable itself caused during movement. When the vibration generated in the coated cable is due to the vibration at the installation location as described above, the vibration measuring means may be fixed to the coated cable,
Alternatively, it may be installed near the coated cable. on the other hand,
It is necessary to fix the covered cable for movement to the cable. In addition, since vibration may occur due to various causes other than the above case, it is generally preferable to fix the vibration measuring means to the coated cable.

The measurement by at least one of the above-mentioned deterioration factor measuring means may be performed continuously or at regular time intervals. In the latter case, it is slightly different depending on the measurement items, but generally, about once / hour to once / day is appropriate. However, depending on the strength of the deterioration factor and the type of the coated cable, about once / year may be sufficient.

The measurement by the above-mentioned deterioration factor measuring means is continued for a certain period of time, for example, 0.5 to 5 years immediately after the cable is laid, and the strength of the deterioration factor during that period is measured and integrated. The distribution of the strength of the deterioration factor is known, and from the distribution, a section or a place where the integrated amount of the strength is particularly large, in other words, there is a high possibility that the deterioration of the coated cable is particularly advanced. According to the present invention, deterioration diagnosis can be performed on the covered cable in such a section or location.

When the coated cable is deteriorated, various characteristics of the cable itself and various characteristics of the organic polymer material forming the coating layer are generally changed from the initial values. Therefore, the degree of deterioration can be diagnosed from at least one of these characteristics. In the present invention, the characteristics for performing the deterioration diagnosis (hereinafter referred to as deterioration diagnosis characteristics) are not particularly limited, but the tensile strength, elongation at break, elastic modulus, and Young's modulus of the organic polymer material forming the coating layer of the coated cable are not limited. Modulus, modulus, dielectric constant, dielectric loss tangent, volume resistivity, AC breakdown voltage strength, impulse breakdown voltage strength, ultrasonic wave propagation characteristics, surface rebound hardness, surface penetration hardness, torsion torque of coated cable,
In addition, since the bending stiffness and the like of the coated cable are generally easy to measure and change relatively clearly with the progress of the deterioration of the coated cable, it is particularly preferable to perform the measurement based on at least one item selected from the group consisting of them. . Of these, the ultrasonic propagation characteristics, surface rebound hardness, surface penetration hardness, and the torsional torque and bending stiffness of the coated cable are so-called non-destructive tests. It has the advantage that it can be measured dynamically or at high frequency. On the other hand, mechanical or electrical properties of organic polymer materials such as tensile strength, elongation at break, elastic modulus, Young's modulus, modulus, dielectric constant, dielectric loss tangent, volume resistivity, AC breakdown voltage strength, impulse breakdown voltage strength, etc. (Hereafter, machine
(Electrical degradation diagnostic characteristics) is necessary to take a part of the coating layer of the cable to be diagnosed and use it as a diagnostic sample. In other words, although there is a defect of partial destructive inspection, the advantage that the characteristics of the coating layer can be directly grasped Therefore, it is suitable for the case where the measurement is required at a long time interval of about once / year.

Since a method of measuring the ultrasonic wave propagation characteristics in the coating layer of the coated cable is well known in the art, such a known method is used in the present invention, for example, as described in Japanese Patent Application Laid-Open No. Hei 7-357.
The ultrasonic wave propagation characteristics in the coating layer may be measured by a method described in JP-A No. 32 or JP-A-7-35733 to diagnose the deterioration. The ultrasonic wave propagation characteristics include an ultrasonic wave propagation speed, an ultrasonic wave propagation time (including a reciprocal of the ultrasonic wave propagation time, and the like).

A method of diagnosing deterioration from a change in the surface rebound hardness of an organic polymer material is well known in the above-mentioned Japanese Patent Publication No. 1-2370 and Japanese Patent Application Laid-Open No. Hei 8-313423. The impact body is caused to collide against the surface of the material, and the speed is measured from a difference in speed before and after the impact body. Generally, organic polymer materials tend to lose elasticity and harden when chemically degraded. This surface rebound hardness can reflect the degree of this hardening due to chemical degradation.

When the organic polymer material loses its elasticity due to chemical deterioration and hardens, the surface rebound hardness increases, the surface penetration hardness also increases, and the torsional torque and bending stiffness of the coated cable itself also increase. Become larger. Therefore, deterioration diagnosis can be performed based on these characteristic changes. The surface penetration hardness can be measured from a pressing load when the pressing needle is pressed into the organic polymer material. The torsional torque and bending stiffness of the coated cable can be measured from the load required by applying the torsional torque and bending while the coated cable itself is in a live state.

When the change in the ultrasonic wave propagation characteristic is used in the deterioration diagnosis in the present invention, the deterioration diagnosis of the coated cable may be performed based on the numerical value obtained from the measurement. However, the correlation between the ultrasonic wave propagation characteristics due to the deterioration of the organic polymer material and the above-mentioned mechanical-electrical deterioration diagnosis characteristics has been separately established, and the ultrasonic wave propagation characteristics that are easy to measure because of non-destructive inspection can be used. It is preferable that the value of the mechanical-electrical deterioration diagnosis characteristic is grasped and the deterioration diagnosis is performed based on the grasped value because the possibility of misdiagnosis is small. The same applies to the relationship between the characteristics that enable nondestructive inspection such as the surface resilience hardness and surface penetration hardness of organic polymer materials, and the torsional torque and bending stiffness of coated cables, and the mechanical-electrical degradation diagnostic characteristics. The same is true for In particular, in the present invention, the correlation between the ultrasonic wave propagation characteristics or the surface rebound hardness and the mechanical-electrical deterioration diagnostic characteristics that have been separately established (hereinafter, this correlation is referred to as “deterioration correlation”) is grasped. It is preferable to perform the deterioration diagnosis based on the value of the mechanical-electrical deterioration diagnosis characteristic.

The organic polymer material includes various compounding agents specific to the specific organic polymer used as the base of the material, for example, an antioxidant, an antioxidant such as an ultraviolet absorber, a processing aid, Several kinds of plasticizers, stabilizers, pigments, crosslinking agents, crosslinking aids, fillers, carbon black and others are blended in usual amounts specific to each blending agent.
The above-mentioned specific organic polymer is generally a synthetic or natural polymer having a mechanical strength that can be used as a so-called mechanical structure material. Examples of organic polymers include resins such as polyethylene, cross-linked polyethylene, polypropylene, polybutene, polyolefins such as poly-4-methylpentene-1, polyamides such as nylon, polyvinyl chloride, polyvinylidene chloride, thermoplastic polyester, and ethylene. -Vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, polytetrafluoroethylene, such as rubber, natural rubber, isoprene rubber,
Butyl rubber, ethylene-propylene copolymer rubber, ethylene-propylene-diene terpolymer rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, ethylene-vinyl acetate copolymer rubber, ethylene-ethyl acrylate copolymer rubber, Chloroprene rubber,
For thermoplastic elastomers such as chlorosulfonated polyethylene rubber, epichlorohydrin rubber, silicone rubber, and fluororubber, styrene-based thermoplastic elastomers such as ABA-type triblock and (AB) _n X-type radial block, blend-type TPO, and partially cross-linked blends Thermoplastic elastomers such as polyolefin-based thermoplastic elastomers such as type TPO and fully cross-linked blended TPO, polyvinyl chloride-based thermoplastic elastomers such as nitrile rubber blends and partially cross-linked nitrile rubber blends, and polyurethane-based thermoplastic elastomers such as polyester and polyether-based ,polyester·
Polyester type thermoplastic elastomers such as polyether type and polyester / polyester type. Especially, resins such as polyvinyl chloride, polyethylene, cross-linked polyethylene, polypropylene, and polytetrafluoroethylene, which are frequently used as organic polymers for cables,
Chloroprene rubber, ethylene-propylene copolymer rubber,
Rubbers such as ethylene-propylene-diene terpolymer rubber, chlorosulfonated polyethylene rubber, and silicone rubber.

According to the study by the present inventors, for many compounding agents, the presence or absence of the compounding in the usual amount does not affect the deterioration correlation due to deterioration of the organic polymer material. When at least one of carbon black, filler and carbon black is blended, the plasticizer slightly varies depending on the type thereof, and the filler and carbon black slightly vary depending on the blending amount.
Therefore, in the present invention, it is preferable to perform the deterioration diagnosis by the following improved diagnosis method.

In the improved diagnostic method, it is first checked whether or not the organic polymer material forming the coating layer of the coated cable to be diagnosed contains at least one of a plasticizer, a filler, and carbon black. . When the organic polymer material contains at least one of them, pay attention to its type if it is a plasticizer, its compounding amount if it is a filler, and its compounding amount if it is carbon black. Alternatively, a deterioration correlation is established for an organic polymer material having a compounding amount. On the other hand, the ultrasonic propagation characteristic or the surface rebound hardness of the organic polymer material of the covered cable to be diagnosed is measured, and the mechanical-electrical deterioration diagnostic characteristic is obtained from the above-described deterioration correlation to determine the deterioration state of the organic polymer material. Diagnose.

Examples of the plasticizer include dimethyl phthalate, diethyl phthalate, dibutyl phthalate,
Phthalic acid derivatives such as di-n-octyl-phthalate, diphenyl-phthalate, diisodecyl-phthalate and di-n-alkyl-phthalate; isophthalic acid derivatives such as dimethyl-isophthalate; di- (2-ethylhexyl) tetrahydrophthalate Tetrahydrophthalic acid derivatives such as dibutyl-adipate, diisodecyl-adipate, di-n-octyl-adipate, di-
adipic acid derivatives such as n-alkyl-adipate,
Tri- (2-ethylhexyl) trimellitate, tri-
n-octyl-trimellitate, tri-isooctyl-
Trimellitate, tri-isodecyl-trimellitate,
Tri-isononyl-trimellitate, higher alcohol-
Trimellitic acid derivatives such as trimellitate, or other acid derivatives.

Examples of the filler include calcium carbonates such as light calcium carbonate and heavy calcium carbonate, clays such as hard clay, soft clay, calcined clay and silane-modified clay, and talc such as mistro vapor talc. , Silica, wollastonite, zeolite, diatomaceous earth, silica sand, barium sulfate, calcium sulfate, lithobone, magnesium oxide, molybdenum disulfide and the like.

Examples of carbon black include channel blacks, SAF, ISAF, N-339, HA
Furnace blacks such as F, MAF, FEF, SRF, GPF, and ECF; thermal blacks such as FT and MT; and conductive blacks such as acetylene black and Ketjen black.

Whether or not the organic polymer material forming the coating layer of the coated cable to be diagnosed contains at least one of a plasticizer, a filler, and carbon black can be examined by various methods. . If the cable manufacturer considers its own insulated cable to be diagnosed, its manufacturing specifications will indicate this, and the cable user will specify the organic polymer material and have the cable manufacturer produce the insulated cable for diagnosis. And so on.

Even in cases other than the cases described above, the type of the organic polymer as the base of the organic polymer material can be determined from the print on the surface of the coated cable, and if the type of the organic polymer is known, the plasticizer, filler, and The presence or absence of carbon black can be estimated with a considerably high probability. Alternatively, take a small amount of organic polymer material from the coated cable,
This can be discriminated by subjecting it to thermogravimetric analysis or infrared absorption spectrum measurement.

If the organic polymer is polyvinyl chloride, a plasticizer is usually compounded, and the type thereof is determined and the amount of the compound is measured by, for example, using a solvent (acetone, methanol, T
The surface of the organic polymer material of the coated cable is rubbed with absorbent cotton containing HF or the like to collect a plasticizer, and the components in the absorbent cotton are analyzed by infrared absorption spectrum, GPC (gel filtration chromatography), HPLC (high-performance liquid). Chromatography).

When the organic polymer is a polyvinyl chloride or rubber-based material, a filler is usually compounded, and the amount of the compound is determined by taking a small sample (several mg) from the coated cable and converting it to TGA ( It can be quantified by analyzing by thermogravimetric analysis). If the organic polymer is a rubber-based material, carbon black is also compounded in addition to the filler, and the compounding amount may be obtained by collecting a sample in the same manner as in measuring the compounding amount of the filler.

Next, a method of establishing the deterioration correlation will be described. Regarding the effect of the type of plasticizer on the relationship,
In general, the differences between the individual members of each acid derivative are otherwise small, rather the differences between each acid derivative are larger. Therefore, in the present invention, when the specific name of the plasticizer to be blended is known, the relationship may be established for the plasticizer with the specific name. The relationship may be established with derivative names such as phthalic acid derivatives, isophthalic acid derivatives, and the like.

When the organic polymer material is, for example, polyvinyl chloride plasticized with a certain phthalic acid derivative, a model composition of polyvinyl chloride containing the phthalic acid derivative is prepared, and the model composition is prepared. The product is formed into a sheet or covered cable of about 0.5 to 5 mm, and in the form of such a formed product, it is deteriorated to various degrees by irradiation or heating, etc. For each product), measure the mechanical-electrical deterioration diagnostic characteristics such as tensile strength, elongation at break, Young's modulus, etc., ultrasonic wave propagation characteristics, surface rebound hardness, etc., and measure the mechanical-electrical deterioration diagnostic characteristics and ultrasonic wave propagation characteristics. And a relation graph between the mechanical-electrical deterioration diagnosis characteristic and the surface rebound hardness are obtained.

When the organic polymer material is, for example, an ethylene-propylene-diene terpolymer rubber containing a specific amount of a filler and a specific amount of carbon black, the rubber containing the specific amount of the filler may be used. A model composition, or a model composition of the rubber containing the specific amount of carbon black is prepared, and the degradation correlation is determined for any of the model compositions in the same manner as in the case of the polyvinyl chloride model composition described above. Establish.

The organic polymer material contains ethylene-propylene-containing a specific amount of a filler and a specific amount of carbon black.
When the rubber composition contains a filler and carbon black, such as a diene terpolymer rubber, a model composition of the rubber containing the specific amount of the filler or a model of the rubber containing the specific amount of the carbon black as described above. The degradation correlation may be established for any one of the compositions, or may be established from both of them. In the latter case, there may be a difference between the one established from one side and the one established from the other side. In such a case, the average value of the two will improve the accuracy of the deterioration diagnosis. Further, when a deterioration correlation is established for a model composition containing both a specific amount of a filler and a specific amount of carbon black, more accurate deterioration diagnosis can be performed. The same applies to organic polymeric materials containing plasticizers and fillers and / or carbon black.

As described above, the type of the plasticizer, particularly its acid derivative, greatly affects the deterioration correlation. However, some of the acid derivatives, such as trimellitic acid derivatives, also greatly affect the relationship.
Therefore, when establishing the relationship, when the specific name of the plasticizer or the name of the acid derivative is found, the presence or absence of the influence of the blending amount of the plasticizer or the acid derivative is investigated in advance. It is preferable to use a model composition containing a specific amount of the plasticizer or a similar acid derivative.

In establishing the deterioration correlation, the blending amount of the plasticizer, filler or carbon black in the organic polymer material in the coated cable to be diagnosed and the one in the model composition match each other. Is preferred.

Each of the above-mentioned model compositions contains, in addition to the plasticizer, filler or carbon black, other compounding agents usually compounded with the organic polymer material, for example, a stabilizer, an antioxidant,
Pigments and processing aids may or may not be blended. In the case of a rubber composition, it is used after being crosslinked in advance by a usual crosslinking agent and a crosslinking technique.

The deterioration correlation generally varies somewhat depending on the deterioration conditions of the organic polymer material. However, in the improved diagnostic method of the present invention, each of the above-mentioned model compositions is subjected to, for example, room temperature to about 250 ° C. and / or radiation irradiation, for example, 1 hour.
The deterioration correlation obtained when deteriorated by γ-ray irradiation of about 0 Gy / h to 10 kGy / h can be actually used for deterioration diagnosis of many coated cables deteriorated under other conditions. However, in order to perform a more accurate deterioration diagnosis, the model composition is deteriorated under conditions that reproduce the deterioration factors grasped in the inventions of the above (1) and (2) or under conditions similar thereto, and such deteriorated compositions are deteriorated. It is preferable to establish a deterioration correlation for.

On the other hand, when the improved diagnostic method is applied to a general or wide range of deterioration diagnosis of a coated cable regardless of whether the composition of the organic polymer material of the coated cable is unknown or known, the following method is used. To do. First, a number of model compositions were prepared in which the type and amount of the plasticizer and the amount of the filler, and the amount of the carbon black were changed for each organic polymer, and the same as described above for each model composition. And measure the necessary items for the deteriorated sample. In this way, it is possible to establish a number of deterioration correlations (hereinafter, referred to as “data group”) using the types and amounts of plasticizers, the amounts of fillers, and the amounts of carbon black as parameters as parameters.

The types of organic polymers frequently used as the organic polymer material of the coated cable are at most about ten or more, including those described above. Among them, the plasticizer is compounded. It is only polyvinyl chloride, and as a plasticizer, it may be an acid derivative name without being an individual specific name, and it is a phthalic acid derivative or trimellitic acid derivative even if it is an acid derivative that is frequently used. . Therefore, it is practically sufficient to establish the above data group only for organic polymers and plasticizers used frequently. The compounding amounts of the plasticizer, the filler and the carbon black in the above-mentioned model composition include the compounding range in a practical coated cable, and are approximately 5-10
The point and the amount of variation are sufficient.

In the above-described general improved diagnosis method, it is preferable to prepare a recording medium on which the following deterioration diagnosis program is recorded. The recording medium is composed of the type of organic polymer used for the organic polymer material of the coated cable to be diagnosed, the type and amount of plasticizer mixed with the organic polymer, the amount of filler, and carbon black. A step of inputting the blending amount of the input information as input information, a step of selecting data having the same conditions as the input information from the data group, and an ultrasonic propagation characteristic or surface of the organic polymer material to be diagnosed. A program for causing a computer to execute a procedure of inputting a rebound hardness and calculating a mechanical-electrical deterioration diagnostic characteristic from the input value and the selected data is recorded.

In the present invention, the remaining life of the covered cable laid for a certain period can be estimated by a method having the following steps α to ε. First, in step α, at least one material selected from the group consisting of the organic polymer material itself forming the coating layer, a reproduction material having the same composition as the organic polymer material, or a material similar to the reproduction material (hereinafter, referred to as a material). , Test materials), the correlation between the heating temperature t and the heating time h (hereinafter, tha correlation) is experimentally established using at least one of the deterioration diagnosis characteristics as a parameter. At this time, the above-mentioned reproduction material or a material similar to the reproduction material may be the same as described above in the deterioration diagnosis method of the present invention, and the deterioration diagnosis characteristics may be the same as those described above, for example, the elongation at break. And ultrasonic wave propagation characteristics.

In the following, the elongation at break is taken as the deterioration diagnostic characteristic, and a general method of establishing a th-th correlation using the elongation at break as a parameter, and a general surplus of a coated cable utilizing the th-th correlation. The life estimation method will be described. The following description of the method for establishing the tha correlation and the method for estimating the remaining life also applies to other deterioration diagnostic characteristics other than the elongation at break.

First, the above-mentioned test material is processed into a sheet having a thickness of, for example, about 1 to 5 mm by press working, and the sheet is used as a heat-degraded sample in an oven at various heating temperatures t for an appropriate time. After heating, the change in the elongation at break with respect to the heating time h is measured at each heating temperature t. At this time, the heating temperature t is preferably as wide as possible and in small increments. However, since heating at a low temperature of 90 ° C. or lower generally slows down the deterioration, it is usually 100 to 20 ° C.
It is preferred that the temperature be in the range of 0 ° C. at least in increments of 50 ° C., and particularly in increments of 20 ° C. On the other hand, the heating time h for each heating temperature t is preferably at least one month, especially at least three months. FIG. 1 is a model graph of the results, in which the horizontal axis represents the heating time h and the vertical axis represents the elongation at break (%) using the heating temperature t (t1 to t4) as a parameter. In addition, as the heat deterioration sample of the test material described above,
It is a matter of course that an undegraded covered cable itself to be subjected to deterioration diagnosis (remaining life estimation target) may be used in place of the above-mentioned pressed sheet.

Next, a constant elongation at break (for example, 20
The relationship between the heating temperature (t1 to t4) at 0%) and the heating time h is read from FIG. 1 and is graphed. FIG. 2 shows an example of this, where the abscissa represents the reciprocal of the absolute temperature T of the heating temperature t, and the ordinate represents the logarithm of the heating time h. %, 2
T- for each of 00%, 250%, and 300%
2 shows an h correlation, a so-called Arrhenius curve. When obtaining an Arrhenius curve on FIG. 2 from the data read from FIG. 1, it is preferable to obtain a linear equation (straight line) that minimizes the correlation coefficient by a least squares method, or a quadratic or higher polynomial. In many cases, it can be approximated by a linear expression (linear line) in practice.

In step β, the elongation at break shown in FIG.
The t-h correlation for a specific parameter value arbitrarily selected from a plurality of t-h correlations for 00%, 150%, 200%, 250%, 300%, etc.
-H Defined as correlation. At this time, the life-th correlation may be selected and set in consideration of the type of the coated cable, the cable management standard of the cable user, or other circumstances. Here, for the purpose of describing the present invention, the ht correlation at 100% elongation at break shown by a thick line is expressed as the life t-.
h The correlation is temporarily determined.

In the step γ, the elongation at break of the organic polymer material forming the coating layer of the coated cable laid for a certain period of time is examined, which is measured by the method described above for the deterioration diagnosis method of the present invention. It can be known from the correlation between the ultrasonic wave propagation characteristic, which is one of the above deterioration correlations, and the elongation at break.

Next, in step δ, the average temperature of the coating layer of the coated cable after the installation for the above-mentioned fixed period is grasped. The average temperature may be the expected operating temperature of the coated cable determined by the cable user, or the expected operating temperature of the coated cable expected from the cable installation environment. Alternatively, there may be a temporary operating temperature for the cable user to formulate a future cable operation plan. In any case, the life t−h at such average temperature
The heating time h2 on the th-h correlation between the heating time h1 on the correlation and the value of the deterioration diagnostic characteristic obtained in step γ is determined.
Assume that the elongation at break of the coating layer obtained in step γ is, for example, 250%, and thereafter, the coated cable is operated at a temperature at which the average temperature of the coating layer is 60 ° C., 70 ° C., 80 ° C., or 90 ° C. Suppose you want to. Operating temperature 9
In the case of 0 ° C., the heating times h1 and h2 on the respective vertical axes at which the elongation at break becomes 100% (point a in FIG. 3) and 250% (point b in FIG. 3) are read.

In step ε, the time difference (h1−h2) between the heating time h1 and the heating time h2 is calculated, and the remaining life of the coated cable is estimated based on the calculated time difference. In the same manner as when the operating temperature is 90 ° C., the operating temperature is set to 80 ° C.
It is possible to know the estimated remaining life in the case of ° C, 70 ° C, and 60 ° C.

For example, with respect to an insulated wire having a polyvinyl chloride sheath layer operated at 60 ° C., the elongation at break of the sheath layer was calculated from the ultrasonic wave propagation speed to be 250%
Met. When the life of the insulated wire is set when the elongation at break of the sheath layer reaches 100%, 250
The time required to decrease from 100% to 100%, ie, the remaining life, was estimated to be 14 years.

[0055]

According to the present invention, differently from the prior art, by installing a plurality of deterioration factor measuring means along the laid covered cable, the deterioration progresses quickly from the strength of the deterioration factor in the covered cable. Since a possible site is detected and the degree of deterioration of the site is diagnosed, the life of the coated cable can be correctly known. In addition, by knowing the part where deterioration rapidly progresses objectively and correctly, the environment of the part can be improved, thereby delaying the progress of the coated cable deterioration and extending the life. Furthermore, according to the remaining life estimating method of the present invention, since the remaining life of each of the coated cables that have been operated for a certain period of time after each operating temperature can be estimated,
It can be removed before the end of its useful life and replaced with a new one as needed, thereby preventing insulation damage and fire accidents of the insulated cable.

[Brief description of the drawings]

FIG. 1 is a model graph showing the relationship between the heating time and the elongation at break, which is used to estimate the remaining life of a coated cable and uses a heating temperature as a parameter for an organic polymer material or the like forming a coating layer of the coated cable. It is.

FIG. 2 is a graph created from the numerical values read from FIG. 1 and showing the relationship between the reciprocal of the heating temperature (absolute temperature T) and the logarithm of the heating time (th-h correlation) using the elongation at break as a parameter. It is.

[Explanation of symbols]

a The point at which the operating temperature (average temperature) on the tha correlation where the elongation at break is 100% is 90 ° C b The operating temperature (average temperature) on the tha correlation where the elongation at break is 250% 90 ° C point

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tetsuya Ashida 8 Nishinocho, Higashikojima, Amagasaki City, Hyogo Prefecture Inside Mitsubishi Cable Industries Co., Ltd. (56) References JP-A-7-35732 (JP, A) JP-A-7-35733 (JP, A) JP-A-8-313423 (JP, A) JP-A-2-38947 (JP, A) A) JP-A-51-92673 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 17/00 H02G 1/06 JICST file (JOIS)

Claims (5)

(57) [Claims] 1. A coating layer formed of an organic polymer material.
In estimating the remaining life of a covered cable,
The organic polymer material itself forming the layer,
Reproduced material with the same composition, or similar
At least one material selected from the group consisting of materials
The ultrasonic propagation characteristic Vts at the reference temperature ts of the material or poor.
Temperature t and heating time h using chemical diagnosis characteristics as parameters
To establish experimentally the correlation (th correlation) with
And at least one arbitrarily selected from the tha correlation.
The ht correlation with respect to the parameter value is expressed as the life tha phase.
A step β defining as a function relationship, the of remaining life estimation target coating cables which are fixed period laid
Ultrasonic propagation characteristics of the organic polymer material forming the covering layer up to Vts
Or the step of obtaining the value of the deterioration diagnostic characteristic, and the coating layer of the coated cable after the above-mentioned fixed period of installation.
Heating time h on lifetime ht correlation at average temperature of
1 and ultrasonic propagation characteristics Vts or deterioration obtained in step γ
Ht correlation for diagnostic characteristic values (parameter values)
Step δ for determining the heating time h2, and the coating time with the time difference between the heating time h1 and the heating time h2.
And a process ε for making the remaining life of the cable
Method for estimating the remaining life of insulated cables. 2. The insulated cable has at least one section thereof.
Cable degradation in the longitudinal direction of the cable
Multiple deterioration factor measurements to understand the distribution of factor strength
Measures, and measure from multiple deterioration factor measuring means.
High strength of deterioration factors in the longitudinal direction of the coated cable
Know the part, and at least use the value of the deterioration diagnosis characteristic of that part.
2. The coating according to claim 1, wherein the coating has been diagnosed to be more deteriorated.
Method for estimating remaining cable life. 3. A deterioration factor measuring means, comprising:
Degree, presence or absence of underwater immersion of coated cable, underwater of coated cable
PH of immersion water during immersion, presence of oil adhesion on coated cable
None, atmospheric humidity, atmospheric hydrogen sulfide concentration, atmospheric acid
Element concentration, atmospheric radiation dose, solar radiation,
The amount of strain of the covered cable,
At least one item selected from the group consisting of
3. The method according to claim 2, which can be measured and / or detected.
Residual life estimation method of coating the cable as claimed. 4. The heating temperature t in the tha correlation is:
The heating time h is the logarithm of the heating time, which is the reciprocal of the absolute temperature T.
The coated cable according to any one of claims 1 to 3,
Remaining life estimation method. 5. A coating layer of a coated cable, wherein the deterioration diagnosis characteristic is
Strength, elongation at break, elasticity
Modulus, Young's modulus, modulus, permittivity, dielectric loss tangent, volume
Resistivity, AC breakdown voltage strength, impulse breakdown voltage strength,
Ultrasonic propagation characteristics, surface rebound hardness, surface penetration hardness,
Cable torsional torque and sheathed cable bending stiffness
At least one item selected from the group consisting of:
Method for estimating remaining life of coated cable according to any of items 1 to 4
Law.