JPH08278254A - Damage inspection apparatus of long-rod insulator - Google Patents

Abstract

PURPOSE: To obtain a damage inspection apparatus by which the damage of a long-rod insulator at every electric train can be inspected automatically while the electric train is running to an inspection and repair depot. CONSTITUTION: A damage inspection apparatus is provided with an optical system 5 which is composed of two light sources 51a, 51b which are arranged and installed at both sidewalls 41 of an inspection and repair depot 4 and which shine illumination light at both side faces of respective long-rod insulators 31 (R), 31 (L) at two electric trains 1M, 1N entering the depot and two each of image receiving cameras 52a, 52b and 53a, 53b. The damage inspection apparatus is constituted of a wheel detector 6 which is installed at the lower part of the optical system 5, a train-number judgment circuit 71 which is installed at a proper place, a shutter control circuit 72, an image processing part 73 which processes image signals of the respective image receiving cameras, a quality judgment part 74 which comprises a microprocessor 745 and a memory 746 and a data processing part 7 which is composed of an output part 75.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for inspecting damage to a long-distance insulator provided on a roof of a train.

[0002]

2. Description of the Related Art In Shinkansen, new trains with higher speed have been developed one after another, and some of them are already in operation. FIG. 8 shows an example of a new train in operation. The train is composed of a plurality of trains, for example 16 trains 1A, 1B, 1C .... Each train receives electric power from the trolley wire 2 by the pantograph 11 and travels.
Is disadvantageous for speeding up due to wind pressure, and there are many opportunities for damage. For this reason, the number of the electric trains is reduced to the minimum necessary, and a method of supplying electric power to several trains from one pantograph 11 is adopted. For this reason, the electric power connecting unit 3 is provided in the connecting portion of each train. It is provided.

FIG. 9 is a plan view and a side view showing the structure of the power connection unit 3. The power connection part 3 is a long insulator having the same structure.
It has 31 (L) and 31 (R), which are adjacent to trains 1M and 1
It is provided to face the roof 12 of N. Each principal insulator 31
The metal plate 33 at the rear end is the support member 35, and the support member 35 is the roof.
They are fixed to 12 respectively, and this portion is covered with an insulating cover 37. A connection cable 34 extends through the center of each long-axis insulator 31, and the connection fittings 32 at the ends thereof are connected to each other by a bent connection conductor 36. Both long stem insulators 31 have a plurality of n fringes 311 (1) to 311 (n), the diameter of each of which is slightly smaller at the tip than at the rear end, and the inclination angle θ _a is about 5 °. Each long insulator 31 is fixed with an inclination of an angle θ _a , and the upper surface of each is substantially horizontal.

[0004]

When the train runs, the long-distance insulator 31 is caused to fall in any fringe 31 due to the collision of gravel.
1 may be damaged. Each fringe 311 is a ceramic (ceramic), the bottom is relatively safe, but the top and both sides are often damaged. Figure 10 shows the fringe 31
This is an example of the damaged state of 1 and it is significantly damaged like (a) or (b). The fringe 311 having a defective outer periphery in this way may be accompanied by cracks or the like inside, so that the insulation of the long insulator 31 deteriorates and cannot withstand the high voltage (20 to 30 kV) of the supplied power. On the other hand, in the past, when a train entered the inspection garage, an inspector climbed on the roof of each train,
Is checked to see if it is good or bad. As a criterion for quality, the fringe 311 has a diameter of about 300 mm, and caution is required when the length of the fringe 311 is 2.5 mm or more. If it is 50 mm or more, it is considered defective and measures such as replacement are taken. ing. However, since such a manual inspection method is inefficient and roof work is dangerous, an apparatus for automatically inspecting each fringe 311 for damage is desired. However, since the quality judgment is based on the length at the outer circumference of the defect as described above, it is necessary to accurately measure the outer circumference. Hereinafter, for convenience, the method of inspecting the outer peripheral length is referred to as an inspection condition. The present invention has been made in view of the above, and an object thereof is to provide an apparatus for automatically inspecting the fringe 311 of each long-distance insulator 31 for breakage in accordance with the above-mentioned inspection conditions.

[0005]

SUMMARY OF THE INVENTION The present invention is a damage inspection device for a long-distance insulator, wherein each of the two trains entering the inspection garage is installed on the ceiling or both side walls of the inspection garage for the train. An optical system consisting of two light sources for illuminating both sides of the porcelain insulator and two image-receiving cameras each set to an appropriate image-receiving angle with respect to these both sides. To arrange. In addition, a wheel detector installed in the lower part of the optical system that detects the wheels of each train entering the repair garage and a wheel detector installed at an appropriate place and detected by the input wheel detector The vehicle number determination circuit that determines and outputs a determination signal, the shutter control circuit that simultaneously releases the shutter of each image receiving camera by inputting the determination signal and images each of the long insulators, and the image signal output from each image receiving camera. An image processing unit for processing and extracting contour lines of a plurality of fringes of each long insulator, and a microprocessor and a memory are provided, and each extracted contour line is sampled by the microprocessor at appropriate intervals. To calculate each coordinate value and compare each calculated coordinate value to the coordinate data of each normal fringe measured in advance and stored in the memory, and the difference between the two is allowed. A larger fringe is determined to be defective, for the defective data, constituted by a quality determining section for outputting by adding the car number of the train indicated by the determination signal. In the above, the direction of the central axis of each long insulator is the X axis, the horizontal direction of the right angle cross section is the Y axis, and the vertical direction is the Z direction.
With the axis as the axis, the image receiving angles of the two image receiving cameras of each set are set to about 60 ° with respect to the YZ plane, and the image capturing range of both image receiving cameras is set to the outer circumference of each fringe of the long insulator. Exclude about 270 °. In the above, the image receiving angle of each of the two image receiving cameras is set to about 45 ° with respect to the X-axis, and each circular fringe of the long insulator is converted into an elliptical shape for imaging. Each of the extracted image signals is processed by the image processing unit to extract an elliptical contour line of each fringe, the ellipse of each extracted contour line is rotated, and its major axis is the Y axis and its orthogonal direction. With the Z-axis, the central coordinate value (y ₀ .z ₀ ) of the ellipse and the radius R _{a of the} major axis are obtained by the microprocessor, and the outer circumference of each circular fringe is divided into a plurality of minute arcs. Divide into equal parts and calculate the minute distance Δy on the Y-axis corresponding to the length ΔL of each arc: Δy = (R _a ² −y ² ) ^1/2 · ΔL / R _a ………… (1) Store in the memory. At this Δy interval, the elliptical contour line is sampled to obtain each Z coordinate value, and the obtained Z coordinate values are previously set to the Δy interval with respect to the normal elliptical contour line of each fringe. In the same manner, the data is sampled and compared with each Z coordinate data stored in the memory.

[0006]

In the above-mentioned damage inspection device for long-distance insulators, the two light sources of the optical system arranged on the ceiling or both side walls of the repair garage are two trains that enter the repair garage at low speed. Illuminating light is radiated to both sides of each long insulator, and the two image receiving cameras of each set are set to appropriate image receiving angles with respect to both sides of the corresponding long insulator. The wheel detector detects the wheels of each train that sequentially enters, and the detection signal is input to the car determination circuit, the car number of each train is determined, and a determination signal is output. The shutter of each image-receiving camera is released and each long insulator is simultaneously imaged. The image signal output from each image receiving camera is processed by the image processing unit to extract contour lines of a plurality of fringes of each long insulator, and these are sampled at appropriate intervals by the microprocessor of the quality determination unit. Coordinate values are calculated. Each calculated coordinate value is compared with the coordinate data of each normal fringe measured in advance and stored in the memory, and a fringe in which the difference between the two is larger than the allowable value is determined to be defective, and for the defective data, The car number of the train indicated by the determination signal is added and output. In the above description, when the image receiving angles of the two image receiving cameras of each set are set to about 60 ° with respect to the YZ plane, the image capturing range of both image receiving cameras is about 270 excluding the outer peripheral bottom surface of each fringe of the long insulator.
The angle becomes °, and an area where damage is likely to occur is imaged. Further, in the above, if the image receiving angle of each image receiving camera is set to about 45 ° with respect to the X axis, an appropriate image receiving angle is obtained for each fringe surface of the long insulator, and each circular fringe is an ellipse for each image receiving camera. It is converted into a shape and imaged.
Each captured image signal is processed by the image processing unit,
The outline of each ellipse is extracted, and the major axis of each is Y
The axis and the minor axis are rotated by an appropriate angle so as to coincide with the Z axis. The central coordinate value (y ₀ , z ₀ ) of the ellipse and the radius R _{a of the} major axis are obtained by the microprocessor,
The minute distance Δy on the Y-axis is calculated by the above equation (1) and stored in the memory. Each Δy corresponds to the length ΔL of a minute circular arc that equally divides the outer circumference of each circular fringe, and Δy
The inspection condition is satisfied by sampling the elliptical contour line at intervals of. Each Z coordinate value obtained from each sampling is previously compared with each Z coordinate data stored in the memory similarly sampled at intervals of Δy with respect to the oval contour line of each normal fringe, and As described above, when the difference between the two is larger than the allowable value, this fringe is determined to be defective.

[0007]

1 to 7 show one embodiment of the present invention,
Figure 1 shows the layout of each image receiving camera, (a) is a plan view, (b)
Is a side view and (c) is a front view. 2 is a schematic block configuration diagram of the data processing unit, FIG. 3 is an analysis diagram of an image receiving angle of each image receiving camera, FIG. 4 is an explanatory diagram of an image receiving range of a long insulator, and an elliptical image of each fringe imaged, FIG. 5 is an explanatory diagram of problems of the sampling method for the elliptical contour line, FIG. 6 is an analysis diagram of the sampling method for equally dividing the outer periphery of the fringe, and FIG.
FIG. 6 is an explanatory diagram of a sampling method of an elliptic contour line according to the present invention.

In FIGS. 1 (a), 1 (b) and 1 (c), 4 indicates an inspection garage, and two light sources 51a and 51b are provided at appropriate positions on both side walls 41 (or ceiling 42) thereof. 2 against the long insulator 21 (R)
An optical system 5 including individual image receiving cameras 52a and 52b and image receiving cameras 53a and 53b for the long insulator 21 (L) is provided. Receiving angle of each image-receiving cameras 52a ～53B is, phi _Y to the Y-axis, phi with respect to the Z axis _Z, phi _X with respect to the X-axis (phi _X is not shown) and, later on these angular relationships To do.
Further, a wheel detector 6 for detecting the wheels 13 of the train 1 to be stored is provided below the optical system 5 with a projector 61 and a light receiving sensor 62.
To provide.

The data processing unit 7 shown in FIG. 2 is composed of a car number determining circuit 71, a shutter control circuit 72, a contour extracting unit 73, a damage determining unit 74 and an output unit 75. The shutter control circuit 72 is connected to the light receiving sensor 62, and the contour extracting unit 73 is composed of four contour extracting circuits 731 to 734, which are respectively connected to the image receiving cameras 52a to 53b. In addition, the damage determination unit 74
Is composed of four A / D converters (A / D) 741 to 744, a microprocessor (MPU) 745, and a memory (MEM) 746, which are connected as shown.

In FIG. 3 (a), each of the image receiving cameras 52a-53
As described above, the image receiving angle of b is φ _X , Y with respect to the X axis.
The axis is φ _Y and the Z axis is φ _Z. Now, let the XYZ coordinates of the image receiving point P ₀ of the image receiving camera be (x ₀ , y
₀ , z ₀ ), and the distance between the coordinate origin O and the point P ₀ is r ₀ , cos φ _X = x ₀ / r ₀ , cos φ _Y = y ₀ / r ₀ , cos φ _Z = z ₀ / r ₀ ( 2), and between them, x ₀ ² + y ₀ ² + z ₀ ² = r ₀ ² (3) holds. Next, in (b), when the angle φ _YZ of the projection point P ₀ ′ of the point P _{0 on} the YZ plane with respect to the Z axis is _calculated ,
The normal cut is tan φ _YZ = y ₀ / z ₀ (4). Both of the image receiving cameras 52a and 52b need to receive the image as wide as possible in the outer periphery except the bottom surface of the long insulator 21 (L). Therefore, the angle φ _YZ is set large, for example, 60 °. The same applies to the other image receiving cameras 53a and 53b. Setting the angle phi _YZ to 60 °, equation (4) is, tan [phi _YZ = √
3 = y ₀ / z ₀ , and from the equation (2), y ₀ / z ₀ = c
Since osφ _Y / cos φ _Z , the following relational expression is obtained: cos φ _Z = cos φ _Y / √3 (5) Here, the angle φ _Y is 45 ° to 7
When the values of the angles φ _X and φ _Z for the respective values are roughly _calculated by the equations (3) and (5) within the range of 0 °, the angle φ _YZ = 60 °
In contrast, an angle table of φ _Y (°) 45 50 55 60 70 φ _X 55 55 48 42 35 33 φ _Z 66 68 70 73 80 is obtained. Here, at the angle φ _X , the long insulator 21
There is an appropriate angular range for imaging each fringe 311 and its damage. For example, if this is set at a high angle, the fringe 311 and its damage overlap and it is difficult to distinguish between them. At low angles, the fringes 311 all overlap and hide the damage. Therefore, it is suitable for the angle φ _X to be around 45 °. Considering that the long insulator 21 is inclined by about 5 ° as described above, the angle φ _{X is set} to 4
When it is set to 2 °, it effectively becomes about 45 °, and the angle φ _Y is determined to be 55 ° and the angle φ _Z is determined to be 70 ° from the above table.

FIG. 4 shows the image receiving range of each of the image receiving cameras 52a to 53b set to the above angles φ _YZ and φ _X. (a) shows the YZ plane, and the angle φ _YZ of 60 ° allows the image receiving camera to be provided unless the distance L between the image receiving camera and the long insulator is very small.
52a (53a) is a point p _a and a point p _{b on} the outer periphery of each fringe 311.
The imaging range is approximately 180 ° between. Similarly, in the image receiving camera 52b (53b), the imaging range is approximately 180 ° between points p _c and p _d , and since both imaging ranges overlap near the top surface, each fringe 311 has an imaging area of approximately 90 ° on the bottom surface. About 27 excluding range
The range of 0 ° is imaged by both image receiving cameras 52a, 52b (53a, 53b). Next, (b) shows the XZ plane, which is an angle φ _{X of} about 45 °.
As a result, each fringe 311 and its damage are picked up by each image receiving camera without overlapping. (c) shows an example of an imaged image, and each circular fringe 311 is imaged after being converted into an ellipse. Defects (a) and (b) in the figure correspond to the defects (a) and (b) in FIG. 10 described above.

Next, a sampling method for inspecting the quality of each fringe 311 imaged in the elliptical shape as described above will be described. In FIG. 5, it is assumed that the outer circumference of the originally circular fringe 311 is converted into the elliptical contour line shown. However, the elliptical shape may be arbitrary. As described above, the quality of the fringe is determined by the length of the outer peripheral length of the defect, and for this purpose, as shown in the left half of FIG. When the contour line is sampled, its length ΔL ′ varies depending on the angle θ, but on the outer periphery of the fringe 311 the above condition is satisfied corresponding to a constant interval ΔL. However, it is unexpectedly difficult to sample the elliptical contour line on the image plane at a constant small angle Δθ. On the other hand, as shown in the right half, for example, when sampling is performed at regular intervals δy in the Y-axis direction, the sampling interval δL on the outer periphery of the circular fringe 311 changes significantly depending on the position of y, and the inspection condition Is not satisfied. Therefore, referring to FIG. 6, the sampling interval in the Y-axis direction that satisfies the inspection condition is analyzed.

In FIG. 6, an arbitrary point p _P on the circumference of the radius R _a is taken and its coordinates are (y _P , z _P ). The circumferential curve is expressed by the following equation: y _P ² + z _P ² = R _a ² (6). Differentiating both sides of the equation (6) and transforming gives dz / dy = y _P / z _P (7), and dL ² = dy ² + dz ² (8). And dy for a given dL, when determined by the above ^{equations, dy 2 = [1- (y} P / R a) 2] · dL 2 ......... (9) will be obtained. Here, dL and dy are infinitesimally differentiating amounts, but the above equations hold even with finite and minute ΔL and Δy. Therefore, by replacing dy and dL with Δy and ΔL and taking the square root, the above equation (1) is obtained. Δy = (R _a ² −y ² ) ^1/2 · ΔL / R _a (1) If the ellipse is sampled with Δy as the interval, the fringe 311 is inspected at a constant ΔL interval on the outer circumference. .

FIG. 7 shows an elliptic contour line sampled by the interval Δy, and each point on the outer circumference of the fringe 311 corresponding to each point p ₁ , p ₂ ... On the Y axis forming the interval Δy. All have a constant interval ΔL. However, since the elliptical contour line in FIG. 7 is inclined with respect to the YZ system as shown in FIG. 4C, it is rotated by an appropriate angle to match the YZ system.

A method of inspecting each fringe 311 will be described below with reference to FIG. 7 and FIG. First, mount the normal long-distance insulator 31 in which each fringe 311 is not damaged, to both the image receiving cameras 52a and 52b.
The image of each contour line is extracted by the contour extraction unit 73 to extract the elliptical contour line, and the data of each contour line extracted is digitized by the A / D converters 741 to 744 and input to the MPU745. Then, the center coordinates (y ₀ ,
z ₀ ) and the radius R _{a of the} major axis are calculated, and Δy for each point y ₁ , y ₂ ... On the Y-axis shown in FIG. 7 is calculated by the formula (1) and stored in the memory 746. Then, MP these
U745 is sequentially read out to sample each point p ₁ ', p ₂ ' ... Of the elliptical contour line corresponding to each point y ₁ , y ₂ ..., and the respective Z coordinate values z ₁ , z ₂ ... Seeking memory 74
Remember in 6. In the memory 746, the allowable value for damage of each fringe 311 is set. In FIG. 1, when a train enters the inspection garage 4 at a low speed V _L , the wheels of each train 1
13 are sequentially detected by the wheel detector 6, and the detection signal is input to the car number judging circuit 71 to judge the car number of the train concerned. When this judgment signal is inputted to the shutter control circuit 72, each of the image receiving cameras 52a to 53b is detected. Each shutter is released, 2
The individual long-distance insulators 31 (R) and 31 (L) are simultaneously imaged. The image signal of each image-receiving camera has a corresponding contour extraction circuit 731-734.
Each elliptical contour line is extracted by
Digitized by the / D converters 741 to 744
Input to 5 and by the same sampling as above, the Z coordinate value of each elliptical contour is obtained and transferred to the MPU755.
As described above, the correct Z coordinate values stored in the memory 746 are compared, and the difference between the two is obtained. If these differences are large and the lengths on the outer circumference that are set in the memory 746 continue and exceed the permissible length, the long insulator 21 is determined to be defective, and the car The car number of the train to which the long-distance insulator 31 belongs is added from the determination circuit 71 and is output to the output unit 75.

[0016]

As described above, according to the damage inspection device for a long-distance insulator of the present invention, each long-distance insulator of each train entering the repair garage at a low speed is provided on both side walls of the repair garage. With each of the image receiving cameras arranged, the fragile range of about 270 ° of the outer periphery excluding the bottom surface of each fringe is sequentially imaged in an elliptical shape without hiding the damage, and each contour line is extracted. These are sampled at intervals of Δy corresponding to a fixed length ΔL of the outer periphery of the fringe, and the quality of each is judged by comparing with the data of each normal fringe. It has a great effect in that it is quickly inspected and contributes to labor saving and risk prevention of the conventional manual inspection work.

[Brief description of drawings]

FIG. 1 shows the arrangement of image receiving cameras, (a) is a plan view, (b) is a side view, and (c) is a front view.

FIG. 2 is a schematic block configuration diagram of a data processing unit.

FIG. 3 is an analysis diagram of an image receiving angle of each image receiving camera, (a) is an explanatory diagram of an image receiving angle, and (b) is an explanatory diagram of a relationship with the Z axis.

FIG. 4 is an explanatory diagram of an image receiving range of a long-stem insulator and an elliptical image of each fringe imaged, (a) is an explanatory diagram of its YZ plane, and (b) is its XZ image. FIG. 3C is an explanatory diagram of a surface, and FIG. 7C is an explanatory diagram of a captured image.

FIG. 5 is an explanatory diagram of a problem of a sampling method for an elliptic contour line.

FIG. 6 is an analysis diagram of a sampling method for equally dividing the outer periphery of a fringe.

FIG. 7 is an explanatory diagram of a sampling method of an elliptic contour line according to the present invention.

FIG. 8 is an organization diagram of a new train.

FIG. 9 is a plan view and a side view showing a configuration of a power connection unit.

FIG. 10 is an external view of a long insulator with a broken fringe.

[Explanation of symbols]

1, 1A, 1B ... Train, 11 ... Pantograph, 12 ... Roof, 13 ... Wheels, 2 ... Trolley wire, 3 ... Power connection part, 31 ... Long insulator, 311 ... Fringe, 32 ... Connection fitting, 33 ... Metal plate ,
34 ... Connection cable, 35 ... Support member, 36 ... Connection conductor, 37 ...
Insulation cover, 4 ... Inspection garage, 41 ... Side wall, 42 ... Ceiling, 5 ...
Optical system, 51a, 51b ... Light source, 52a, 52b, 53a, 53b ... Image receiving camera, 6 ... Wheel detector, 61 ... Emitter, 62 ... Light receiving sensor, 7
... data processing unit, 71 ... car determination circuit, 72 ... shutter control circuit, 73 ... contour extraction unit, 731 to 734 ... contour extraction circuit,
74 ... Pass / fail judgment unit, 741 to 744 ... A / D converter, 745 ... Microprocessor (MPU), 746 ... Memory (ME
M), 75 ... Output unit, φ _X , φ _Y , φ _Z ... X of image receiving camera,
Image receiving angle with respect to Y and Z axes, φ _YZ ... Image receiving angle with respect to YZ plane of image receiving camera.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichi Fukuhara 3-16-3 Higashi, Shibuya-ku, Tokyo Hitachi Electronics Engineering Co., Ltd.

Claims (3)

[Claims] 1. A simultaneous inspection of two long-distance insulators for a connecting conductor of electric power from a pantograph, which is provided on two adjacent roofs of a train composed of a plurality of trains so as to face each other. In the ceiling or both side walls of the inspection garage for the train, two light sources that irradiate illumination light to both side surfaces of each of the two main insulators that enter the inspection garage, and An optical system consisting of two sets of two image-receiving cameras, each set at an appropriate image-receiving angle with respect to both side surfaces of the long insulator, is provided, and the optical system is provided below the optical system. Wheel detectors that detect the wheels of each train entering the car, and the car number that determines the car number of each train by the input detection signal of each wheel detector that is provided at an appropriate location and outputs a judgment signal. A circuit and a shutter of each of the image receiving cameras by inputting the determination signal. A shutter control circuit that simultaneously cuts each of the long stem insulators, processes an image signal output from each of the image receiving cameras, and extracts an outline of a plurality of fringes of each long stem insulator. And a microprocessor and a memory, each of the extracted contour lines is sampled by the microprocessor at appropriate intervals to calculate each coordinate value, and each calculated coordinate value is measured in advance. The normal fringe coordinate data stored in the memory is compared with each other, and a fringe whose difference between the two is larger than the allowable value is determined to be defective, and the car number indicated by the determination signal is added to the defective data. A damage inspection device for a long-distance insulator, comprising: a damage determination unit for outputting. 2. A central axis of each of the long insulators is defined as an X axis, a horizontal direction of a right-angled cross section is defined as a Y axis, and a vertical direction is defined as a Z axis, and an image receiving angle of each of the two image receiving cameras is defined as YZ. Each of them is set at about 60 ° with respect to the surface, and the imaging range of both of the image receiving cameras is set to about 2 at the outer circumference of each fringe of the long insulator except for the bottom surface.
It is 70 degrees, The damage inspection apparatus of the long insulator of Claim 1 characterized by the above-mentioned. 3. The image receiving angles of the two image receiving cameras of each set are set to about 45 ° with respect to the X-axis, respectively, and each circular fringe of the long insulator is converted into an elliptical shape. The captured image signal is processed by the image processing unit, the elliptical contour line of each fringe is extracted, and the elliptical contour line of each extracted contour line is rotated. The major axis is made to coincide with the Y axis, and the direction perpendicular thereto is made to coincide with the Z axis, and the central coordinate value (y
₀ .z ₀₎ and, respectively obtained and the radius R _a of the long axis, the circular outer peripheral of each fringe aliquoted into a plurality of small circular arc, each of said arc on the Y-axis corresponding to the length ΔL Minute distance Δy: Δy = (R _a ² −y ² ) ^1/2 · ΔL / R _a ... (1) is calculated and stored in the memory, and the elliptical contour is formed at intervals of Δy. The line is sampled to obtain each Z coordinate value, and each obtained Z coordinate value is sampled in advance in the same manner at the interval of Δy with respect to the oval contour line of each normal fringe in advance. The damage inspection device for a long insulator according to claim 1 or 2, which compares the stored Z coordinate data.