Water-turbine generator set center measuring device and measuring method

Abstract

The invention discloses a water turbine generator set center measuring device and measuring method, and relates to the technical field of water turbine main shaft installment, the water turbine generator set center measuring device comprises a camera installed on a centering device, the centering device is connected to a horizontal center frame, the horizontal center frame is connected with a support, and the support is connected with an identification plate parallel to the horizontal center frame. A plurality of rows of calibration rulers and calibration centers with the same length are arranged on the identification plate; the camera is connected with a computer through a signal line, and an image processing module for processing pictures, a calibration module and a center determination module are arranged in the computer; the marking plate comprising a plurality of calibration rulers is selected as a reference object to realize accurate positioning of the midpoint position of the horizontal center frame, so that accurate positioning of the center of the water-turbine generator set is realized, a worker does not need to go to a high altitude for manual adjustment, the accuracy is improved, the adjustment difficulty is reduced, and the working efficiency is improved. Therefore, the efficiency is higher and the risk is lower when a worker determines the center of the water-turbine generator set.

Description

Technical Field

[0001] The invention relates to the technical field of water turbine main shaft installation, and in particular to a water turbine generator set center measuring device and a measuring method. Background Art

[0002] A hydroelectric generator set is a machine that converts water energy into rotational mechanical energy and then into electrical energy. Therefore, the hydroelectric generator set is subject to multiple forces such as water, mechanical and electromagnetic forces during operation, which causes hydraulic, mechanical and electromagnetic vibrations in the load-bearing frame of the unit. When the vibration amplitude exceeds the allowable range, it may cause damage to the unit components, posing a serious threat to the safe and stable operation of the hydroelectric generator set. The amplitude of the unit's vibration and swing is one of the most important criteria for measuring the quality of the unit. It reflects the level of design, manufacturing, installation and maintenance technology, so it is a comprehensive performance standard.

[0003] One of the main reasons for the vibration of the unit is the poor quality of axis processing and adjustment, which will increase the swing of the rotating parts of the unit and transmit it to the bearings and frames to cause vibration. In order to reduce the vibration and swing of the unit and create conditions for the safe and stable operation of the unit, the center axis needs to be measured and adjusted during the installation of the unit so that the verticality between the center axis and the mirror plate mirror surface reaches the allowable standard.

[0004] The existing axis measurement method is the piano wire method. The piano wire method is to set up a structural steel frame on the flange surface of the central axis, and set hanging wire arms at each azimuth of the steel frame corresponding to each measuring point of the central axis. Piano wires and weights are hung on the arms, and the vertical effect of the earth's gravity is used to measure the distance from each measuring point to the piano wire with an inside micrometer. The axis deviation value between the upper and lower relative points is then calculated by symmetrical subtraction and subtraction of the upper and lower relative points.

[0005] However, the current measurement method mainly relies on manual adjustment at a height of more than ten meters, which is highly dangerous and has low work efficiency. Summary of the invention

[0006] Based on the problems existing in the background technology, the purpose of the present invention is to provide a center measuring device and method for a hydro-turbine generator set, which can not only realize remote control and adjustment, avoid high-altitude operations, reduce danger, and improve work efficiency, but also make the center positioning of the hydro-turbine generator set more accurate.

[0007] The present invention is achieved through the following technical solutions:

[0008] In a first aspect, the present application provides a method for measuring the center of a hydro-generator set, comprising the following steps:

[0009] S1, use the camera to collect the target image;

[0010] S2, cropping the target image, decomposing the cropped image into three channels of red, green and blue, applying the CLAHE algorithm to the three channels, and then recombining the three channels to obtain an RGB-CLAHE processed image;

[0011] S3, obtaining the RGB value of the target pixel of the image after RGB-CLAHE processing, setting the distance threshold according to the clarity of the target object contour on the target image, and calculating the distance between each pixel on the target image and the RGB value of the target pixel in turn; if the distance of the RGB value satisfies the following formula, the pixel is judged to be a pixel with a color close to that of the target pixel: (Ra) 2 +(Gb) 2 +(Bc) 2 ≤L 2 ; Wherein, R, G, and B are the values ​​of the corresponding color channels corresponding to the RGB values ​​of the pixels on the target image; a, b, and c are the values ​​of the corresponding color channels corresponding to the RGB values ​​of the target pixels, and L is the preset distance threshold;

[0012] S4, obtaining a set corresponding to all continuous pixels according to the positional relationship between each pixel and other pixels in the pixel points, and obtaining all continuous regions according to the set corresponding to the continuous pixels;

[0013] S5, sorting all the continuous regions according to the number of pixels corresponding to each of the continuous regions, and enhancing all the pixels in the continuous regions;

[0014] S6, the first detection module obtains the pixel distance between the center of the calibration ruler and the two sides of the calibration ruler in the target image after pixel enhancement;

[0015] S7, the second detection module obtains the pixel length of each row of the calibration ruler in the identification plate in the target image after pixel enhancement;

[0016] S8. Determine whether the pixel length of each row of the calibration ruler is abnormal according to a preset judgment condition. If abnormal, remove it, and calibrate the pixel length of the calibration ruler that is not removed to obtain the pixel length of the calibrated calibration ruler; the calibration module is also used to determine an object ratio coefficient k according to the length of the calibration ruler and the pixel length of the calibrated calibration ruler, where Where D is the length of the calibration ruler, is the pixel length of the calibrated ruler;

[0017] S9, according to the determined object scale coefficient k and the pixel distance M on both sides of the calibration ruler, the midpoint C of the horizontal center frame, and at the same time according to the object image, determine whether the centering device is located on the left or right side of the center point. If it is on the left side, move it to the right by a distance S, and if it is on the right side, move it to the left by a distance S; wherein S = k*M / 2;

[0018] S10, marking the obtained midpoint position in the target image and displaying it through a display terminal.

[0019] In a second aspect, the present application provides a computer program, which can implement the steps of the above method.

[0020] In a third aspect, the present application provides a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the above method.

[0021] In a fourth aspect, the present application provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the above method.

[0022] In a fifth aspect, the present application provides a device for measuring the center of a hydro-turbine generator set, comprising a camera mounted on a centring device, wherein the centring device is connected to a horizontal center frame, a bracket is connected to the horizontal center frame, an identification plate parallel to the horizontal center frame is connected to the bracket, and a plurality of rows of calibration scales and calibration centers of the same length are arranged on the identification plate;

[0023] The camera is connected to a computer via a signal line, and the computer is provided with an image processing module, a calibration module, and a center determination module for processing images;

[0024] The camera is used to capture a target image, wherein the target image includes multiple rows of calibration rulers of the same length on the identification plate, and the calibration rulers are of standard length;

[0025] The image processing module includes an image enhancement module, a first detection module and a second detection module;

[0026] The first detection module is used to obtain the pixel distance between the center of the calibration ruler and the two sides of the calibration ruler in the target image;

[0027] The second detection module is used to obtain the pixel length of each row of the calibration ruler in the target image;

[0028] The calibration module is used to determine whether the pixel length of each row of the calibration ruler is abnormal according to a preset judgment condition. If it is abnormal, it is removed, and the pixel length of the calibration ruler that is not removed is calibrated to obtain the pixel length of the calibrated calibration ruler;

[0029] The center determination module is used to calculate the center point according to the determined object-image ratio coefficient and the pixel distance between the two ends of the horizontal center frame, and display it through the display terminal.

[0030] Furthermore, the calibration module is further used to determine an object-image ratio coefficient according to the length of the calibration ruler and the pixel length of the calibrated calibration ruler.

[0031] Furthermore, judging whether the pixel length of each row of the calibration ruler is abnormal according to the preset judgment condition is specifically:

[0032] The standard deviation S and the average value are calculated based on the pixel length of each row of the calibration ruler in the identification plate.

[0033] like Then X i is abnormal data, where X i is the pixel length of the i-th calibration ruler, i=1,2,…,i; i is the number of the calibration rulers, and N is a preset constant factor.

[0034] Furthermore, the object-image ratio coefficient is Where D is the length of the calibration ruler, is the pixel length of the calibrated ruler.

[0035] Furthermore, the number I of the calibration rulers satisfies: 5≤I≤20.

[0036] Furthermore, each row of the calibration ruler includes a plurality of letters arranged in sequence along the same straight line.

[0037] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0038] The method for measuring the center of a hydro-turbine generator set of the present application enhances the target image by performing multiple processing on the target image, expands the data set, and makes the sample richer. At the same time, the identification plates of multiple calibration scales are used as reference objects to achieve accurate positioning of the midpoint of the horizontal center frame, thereby achieving accurate positioning of the centring device, so that the piano wire connected to the centring device is exactly located at the center axis of the hydro-turbine generator, and there is no need to measure with an inside micrometer. Not only does it achieve accurate positioning of the center of the hydro-turbine generator set, but it also eliminates the need for staff to manually adjust it at high altitudes, thereby improving accuracy and reducing the difficulty of adjustment. Staff only need to operate on the computer to complete the adjustment of the position of the ball centring device, which makes staff more efficient and less dangerous when determining the center of the hydro-turbine generator set. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0040] Figure 1 A flow chart of a method for measuring the center of a hydro-generator set in the present invention;

[0041] Figure 2 A top view of the hydro-generator set during detection in the present invention;

[0042] Figure 3 It is a schematic diagram of the structure of the identification plate in the present invention.

[0043] Marks and corresponding parts names in the attached drawings:

[0044] 01- horizontal center frame, 02- bracket, 03- identification plate, 04- camera, 05- centering device. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0046] Therefore, the detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] Example 1

[0048] like Figures 1 to 3 As shown, this embodiment provides a method for measuring the center of a hydro-generator set, and the specific method is as follows:

[0049] S1. Use a camera to capture a target image; a calibration scale consisting of 7 rows of letters "N" of the same length is set on the identification plate;

[0050] S2, cropping the target image, decomposing the cropped image into three channels of red, green and blue, applying the CLAHE algorithm to the three channels, and then recombining the three channels to obtain an RGB-CLAHE processed image;

[0051] Specifically, clipping is achieved through the following formula:

[0052] Lc=aL+βG(σ)*L+γ;

[0053] Among them, Lc represents the image after shearing, α represents the preset parameter for controlling the overall intensity of the original image, L represents the sheared image, β represents the preset parameter for controlling the influence of the minimum pooling filter on the image, G(σ) represents a Gaussian filter with a standard deviation of σ, * represents a convolution operation, and γ represents the preset parameter for controlling the overall brightness offset and contrast of the output image.

[0054] S3, obtaining the RGB value of the target pixel of the image after RGB-CLAHE processing, setting the distance threshold according to the clarity of the target object contour on the target image, and calculating the distance between each pixel on the target image and the RGB value of the target pixel in turn; if the distance of the RGB value satisfies the following formula, the pixel is judged to be a pixel with a color close to that of the target pixel: (Ra) 2 +(Gb) 2 +(Bc) 2 ≤L 2 ; Wherein, R, G, and B are the values ​​of the corresponding color channels corresponding to the RGB values ​​of the pixels on the target image; a, b, and c are the values ​​of the corresponding color channels corresponding to the RGB values ​​of the target pixels, and L is the preset distance threshold;

[0055] S4, obtaining a set corresponding to all continuous pixels according to the positional relationship between each pixel and other pixels in the pixel points, and obtaining all continuous regions according to the set corresponding to the continuous pixels;

[0056] Among them, if any two pixel points (a0, b0) and (a1, b1) satisfy -1≤a0-a1≤1 and -1≤b0-b1≤1, then the two pixel points are determined to be continuous pixel points;

[0057] S5, sorting all the continuous regions according to the number of pixels corresponding to each of the continuous regions, and enhancing all the pixels in the continuous regions;

[0058] S6, the first detection module obtains the pixel distance between the center of the calibration ruler and the two sides of the calibration ruler in the target image after pixel enhancement;

[0059] S7, the second detection module obtains the pixel length of each row of the calibration ruler in the identification plate in the target image after pixel enhancement;

[0060] S8. Determine whether the pixel length of each row of the calibration ruler is abnormal according to the preset judgment condition. If abnormal, remove it, and calibrate the pixel length of the calibration ruler that is not removed to obtain the pixel length of the calibrated ruler after calibration; the calibration module is also used to determine an object ratio coefficient k according to the length of the calibration ruler and the pixel length of the calibrated calibration ruler, where k=D / D; where D is the length of the calibration ruler, is the pixel length of the calibrated ruler;

[0061] S9, according to the determined object scale coefficient k and the pixel distance M on both sides of the calibration ruler, the midpoint C of the horizontal center frame, and at the same time according to the object image, determine whether the centering device is located on the left or right side of the center point. If it is on the left side, move it to the right by a distance S, and if it is on the right side, move it to the left by a distance S; wherein S = k*M / 2;

[0062] S10, marking the obtained midpoint position in the target image and displaying it through a display terminal.

[0063] In the measuring method of the center measuring device of the hydro-turbine generator set, an identification plate containing multiple calibration scales is selected as a reference object to achieve accurate positioning of the midpoint position of the horizontal center frame, and then to achieve accurate positioning of the centring device, so that the piano wire connected to the centring device is exactly located at the center axis of the hydro-turbine generator, and there is no need to measure with an inside micrometer. Not only does it achieve accurate positioning of the center of the hydro-turbine generator set, but it also does not require staff to go to high altitudes for manual adjustment, which improves accuracy and reduces adjustment difficulty. Staff only need to operate on the computer to complete the adjustment of the ball centering device, which makes staff more efficient and less dangerous when determining the center of the hydro-turbine generator set.

[0064] Example 2

[0065] like Figure 2 and Figure 3 As shown, this embodiment provides a device for measuring the center of a hydro-generator set, including a camera 04 mounted on a centring device 05, the centring device 05 is connected to a horizontal center frame 01, the horizontal center frame 01 is connected to a bracket 02, the bracket 02 is connected to an identification plate 03 parallel to the horizontal center frame 01, and the identification plate 03 is provided with multiple rows of calibration rulers and calibration centers of the same length;

[0066] The camera 04 is connected to the computer via a signal line, and the computer is provided with an image processing module, a calibration module, and a center determination module for processing the image;

[0067] The camera 04 is used to capture the target image, which includes multiple rows of calibration rulers of the same length on the identification plate 03, and the calibration rulers are of standard length;

[0068] The image processing module includes an image enhancement module, a first detection module and a second detection module;

[0069] The first detection module is used to obtain the pixel distance between the center of the calibration ruler and the two sides of the calibration ruler in the target image;

[0070] The second detection module is used to obtain the pixel length of each row of the calibration ruler in the target image;

[0071] The calibration module is used to determine whether the pixel length of each row of the calibration ruler is abnormal according to the preset judgment conditions. If it is abnormal, it is removed, and the pixel length of the calibration ruler that is not removed is calibrated to obtain the pixel length of the calibrated calibration ruler;

[0072] The center determination module is used to calculate the center point according to the determined object-image ratio coefficient and the pixel distance between the two ends of the horizontal center frame 01, and display it through the display terminal.

[0073] Specifically, the calibration module is further used to determine an object-image ratio coefficient according to the length of the calibration ruler and the pixel length of the calibrated calibration ruler.

[0074] Example 3

[0075] This embodiment provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method for measuring the center of a hydro-turbine generator set in the above-mentioned embodiment 2.

[0076] The computer device may be a desktop computer, a notebook, a PDA, a cloud server, etc. The computer device may interact with the user through a keyboard, a mouse, a remote control, a touch pad, or a voice control device.

[0077] The storage includes at least one type of readable storage medium, and the readable storage medium includes flash memory, hard disk, multimedia card, card-type memory (for example, SD or D interface display memory, etc.), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic memory, disk, optical disk, etc. In some embodiments, the memory can be an internal storage unit of the computer device, for example, a hard disk or memory of the computer device. In other embodiments, the memory can also be an external storage device of the computer device, such as a plug-in hard disk equipped on the computer device, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (FlashCard), etc. Of course, the memory can also include both the internal storage unit of the computer device and an external storage device. In this embodiment, the memory is often used to store the operating system and various application software installed on the computer device, such as the program code for running the simulation method of the extension law of acid fracturing fractures in deep cloud-ash interlaced reservoirs, etc. In addition, the memory may also be used to temporarily store various types of data that have been output or are to be output.

[0078] In some embodiments, the processor may be a central processing unit (CPU), a controller, a microcontroller, a microprocessor, or other data processing chip. The processor is generally used to control the overall operation of the computer device. In this embodiment, the processor is used to run the program code stored in the memory or process data, such as running the program code of the method for simulating the extension law of acid fracturing fractures in deep cloud-ash interlaced reservoirs.

[0079] Example 4

[0080] This embodiment provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the processor executes the steps of the method for measuring the center of a hydro-turbine generator set in the above-mentioned embodiment 2.

[0081] The computer-readable storage medium stores an interface display program, and the interface display program can be executed by at least one processor so that the at least one processor executes the steps of the method for simulating the extension law of acid fracturing fractures in deep cloud-ash interlaced reservoirs.

[0082] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes a number of instructions for a terminal device (which can be a mobile phone, computer, server or network device, etc.) to execute the methods described in each embodiment of the present application.

[0083] The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only the specific embodiments of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention. For those skilled in the art, it is obvious that the present application is not limited to the details of the above exemplary embodiments, and the present application can be implemented in other specific forms without departing from the spirit or basic features of the present application. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present application is limited by the attached claims rather than the above description, and it is intended to include all changes within the meaning and scope of the equivalent elements of the claims in the present application.

Claims

1. A method for measuring the center of a hydro-generator set, characterized in that: The following steps are involved: S1, use the camera to collect the target image; S2, cropping the target image, decomposing the cropped image into three channels of red, green and blue, applying the CLAHE algorithm to the three channels, and then recombining the three channels to obtain an RGB-CLAHE processed image; S3, obtaining the RGB value of the target pixel of the image after RGB-CLAHE processing, setting the distance threshold according to the clarity of the target object contour on the target image, and calculating the distance between each pixel on the target image and the RGB value of the target pixel in turn; if the distance of the RGB value satisfies the following formula, the pixel is judged to be a pixel with a color close to that of the target pixel: (Ra) 2 +(Gb) 2 +(Bc) 2 ≤L 2 ; Wherein, R, G, and B are the values ​​of the corresponding color channels corresponding to the RGB values ​​of the pixels on the target image; a, b, and c are the values ​​of the corresponding color channels corresponding to the RGB values ​​of the target pixels, and L is the preset distance threshold; S4, obtaining a set corresponding to all continuous pixels according to the positional relationship between each pixel and other pixels in the pixel points, and obtaining all continuous regions according to the set corresponding to the continuous pixels; S5, sorting all the continuous regions according to the number of pixels corresponding to each of the continuous regions, and enhancing all the pixels in the continuous regions; S6, the first detection module obtains the pixel distance between the center of the calibration ruler and the two sides of the calibration ruler in the target image after pixel enhancement; S7, the second detection module obtains the pixel length of each row of the calibration ruler in the identification plate in the target image after pixel enhancement; S8. Determine whether the pixel length of each row of the calibration ruler is abnormal according to a preset judgment condition. If abnormal, remove it, and calibrate the pixel length of the calibration ruler that is not removed to obtain the pixel length of the calibrated calibration ruler; the calibration module is also used to determine an object ratio coefficient k according to the length of the calibration ruler and the pixel length of the calibrated calibration ruler, where Where D is the length of the calibration ruler, is the pixel length of the calibrated ruler; S9, according to the determined object scale coefficient k and the pixel distance M on both sides of the calibration ruler, the midpoint C of the horizontal center frame, and at the same time according to the object image, determine whether the centering device is located on the left or right side of the center point. If it is on the left side, move it to the right by a distance S, and if it is on the right side, move it to the left by a distance S; wherein S = k*M / 2; S10, marking the obtained midpoint position in the target image and displaying it through a display terminal.

2. A computer program, characterized in that The computer program can implement the steps of the method according to claim 1.

3. A computer-readable storage medium, characterized in that: A computer program is stored, and when the computer program is executed by a processor, the processor is caused to perform the steps of the method according to claim 1.

4. A computer device, characterized in that: The device comprises a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method according to claim 1.

5. A device for measuring the center of a hydro-generator set, characterized in that: It includes a camera mounted on a centroid, the centroid is connected to a horizontal center frame, the horizontal center frame is connected to a bracket, the bracket is connected to an identification plate parallel to the horizontal center frame, and the identification plate is provided with multiple rows of calibration rulers and calibration centers of the same length; The camera is connected to a computer via a signal line, and the computer is provided with an image processing module, a calibration module, and a center determination module for processing pictures; The camera is used to capture a target image, wherein the target image includes multiple rows of calibration rulers of the same length on the identification plate, and the calibration rulers are of standard length; The image processing module includes an image enhancement module, a first detection module and a second detection module; The first detection module is used to obtain the pixel distance between the center of the calibration ruler and the two sides of the calibration ruler in the target image; The second detection module is used to obtain the pixel length of each row of the calibration ruler in the target image; The calibration module is used to determine whether the pixel length of each row of the calibration ruler is abnormal according to a preset judgment condition. If it is abnormal, it is removed, and the pixel length of the calibration ruler that is not removed is calibrated to obtain the pixel length of the calibrated calibration ruler; The center determination module is used to calculate the center point according to the determined object-image ratio coefficient and the pixel distance between the two ends of the horizontal center frame, and display it through the display terminal.

6. A device for measuring the center of a hydro-generator set according to claim 5, characterized in that: The calibration module is also used to determine an object-image ratio coefficient according to the length of the calibration ruler and the pixel length of the calibrated calibration ruler.

7. A device for measuring the center of a hydro-generator set according to claim 5, characterized in that: The method of judging whether the pixel length of each row of the calibration ruler is abnormal according to the preset judgment conditions is as follows: The standard deviation S and the average value are calculated based on the pixel length of each row of the calibration ruler in the identification plate. like Then X i is abnormal data, where X i is the pixel length of the i-th calibration ruler, i=1,2,…,i; i is the number of the calibration rulers, and N is a preset constant factor.

8. A device for measuring the center of a hydro-generator set according to claim 5, characterized in that: The object-image ratio coefficient is Where D is the length of the calibration ruler, is the pixel length of the calibrated ruler.

9. A device for measuring the center of a hydro-generator set according to claim 5, characterized in that: The number I of the calibration rulers satisfies: 5≤I≤20.

10. A device for measuring the center of a hydro-generator set according to claim 5, characterized in that: Each row of the scale includes a plurality of letters arranged in sequence along the same straight line.

Images