JPH02205766A - Generator inspection equipment - Google Patents

Abstract

PURPOSE:To make it possible to judge the position of a part where a crack occurs and the size of the crack by performing scanning with a measuring head in the horizontal direction and the vertical direction, measuring the distribution of the potential differences at the side surface of an F lead, and analyzing the distribution of the measured potential differences. CONSTITUTION:In an inspecting apparatus, a DC is applied on the surface of a member through a pair of current feeding terminals 8 and 8'. A pair of potential-difference measuring terminals 9 and 9' are provided between a pair of the current feeding terminals 8 and 8'. A defect is detected based on the measured potential difference. on a rectangular parallelopiped main body 1, the following parts are provided: legs 15 and 16 whose heights can be adjusted; fixing legs 11 and 11' which fix the main body 1 to the side wall of a slot; and an air cylinder 12 which fixes the main body in the direction of the width. A flexible flange in a spring type and the like and a guide bar are attached to one end of the main body 1. A U-shaped member 2 is attached to another end. A guide bar is provided on the member 2, and a T-shaped measuring head part 4 which can be slidden along said bar is attached. Air cylinders 6 and 6' are attached to the measuring head 4. A measuring head 7 is attached to the tips of the pistons of the cylinders 6 and 6'. The current feeding terminals 8 and 8' and the measuring terminals 9 and 9' are attached to both ends of the head 7.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a crack detection technique for detecting the shape of a crack generated in a metal structural member, and in particular, it relates to a crack detection technique for detecting the shape of a crack generated in a metal structural member. The present invention relates to a device suitable for detection.

[Prior art]

Conventional devices, as described in JP-A-58-215545 (Inspection device (Mitsubishi Heavy Industries)), run along the inner surface of a pipe and measure the potential difference distribution using a so-called contact terminal. The structure is not such that it is possible to detect cracks in the F lead of the turbine generator, which is the subject of this study.

[Problem to be solved by the invention]

Turbine generator F-lead inspections are carried out in various forms, but when inspecting at a power plant, the range that can be disassembled is limited, and the inspection must be carried out inside a narrow slot (approximately 90mm wide and 700mm deep). . Furthermore, since cracks occur near the R section, only penetrant testing can be applied.

However, penetrant testing can only detect the presence or absence of cracks, and cannot detect the shape of cracks. In addition, the conventional technology uses a pipe inner surface traveling device with a four-terminal measurement head that can measure the potential difference distribution on the inner surface of the pipe while moving, but it is limited to application to small diameter pipes and can be used for other shapes of pipes. There was a problem that it could not be applied to structural members.

The purpose of the present invention is to detect cracks that occur in the F lead of a turbine generator, so that the F lead can be inserted into and removed from the inside of the slot in which the F lead is housed, and can be fixed to the side wall of the slot.
A PDM (direct current potential method) measurement head is scanned in the horizontal and vertical directions of the F lead to measure the potential difference distribution on the side surface of the F lead, and the measured potential difference distribution is analyzed using a unique method to detect cracks. The object of the present invention is to provide a device that can determine the location and size of a crack.

[Means to solve the problem]

The above purpose is to provide a housing which can be inserted into the slot in which the F lead is housed and which can be fixed to the side wall of the slot with an air cylinder, and a measuring rod part that can be moved horizontally using a worm gear and a screw. An air cylinder that can be driven in a direction perpendicular to the F lead surface is attached to it, a measurement head is attached to the shaft end of the air cylinder, and a power supply terminal and measurement terminal for detection by PDM (direct current potential method) are attached to both ends of the measurement head. by placing it vertically and changing the height of the screw for adjusting the height of the housing. Alternatively, the height of the housing can be changed by replacing the screws, and the horizontal potential difference distribution on the side surface of the F lead can be measured by scanning the measurement head horizontally using a worm mechanism driven by a stepping motor and the screws. This is achieved by making it possible to measure the horizontal and vertical potential difference distributions on the sides of the F lead as a whole.

[Effect]

Positioning legs and fixing air cylinders are arranged in two directions within the horizontal plane of the slot in a casing placed inside the slot of the turbine generator F lead, so that the casing can be fixed;
A height-adjustable leg or a large number of legs with different heights are provided at the bottom of the casing, so that the height of the entire casing can be adjusted. A guide rod is attached to the rear of the housing via a universal joint,
The entire device can be taken in and out of the slot. A U-shaped member is provided at one end of the casing, and two guides are provided in the horizontal direction inside the U-shaped member, and the - is a screw.

The measuring head is movable along the guide, and can be moved in the horizontal direction by fitting a worm gear fitted into a screw with a worm attached to the shaft of a motor provided in the measuring head. An air cylinder that can be driven horizontally is attached to the side of the measuring head section facing the F lead, and the measuring head is attached to the axial end of the air cylinder, so that the measuring head is pressed against the side surface of the FIJ-de. By vertically arranging the power supply terminal and measurement terminal for detection using PDM (direct current potential method) on the measurement head, it is possible to measure the vertical potential difference on the side surface of the F lead, so the measurement head can be scanned horizontally. Since the potential difference distribution across the F lead can be measured by changing the height of the entire casing, the position and shape of a crack that has occurred in the F lead can be determined with high accuracy.

[Embodiments of the invention]

An embodiment of the present invention will be described below. Figures 1 and 2 show an embodiment of the generator inspection device of the present invention.
The figure is a front view, and FIG. 2 is a plan view. In FIGS. 1 and 2, the generator inspection device main body 1 is placed on the upper surface of the generator F lead 50. As shown in FIGS. The main body 1 is provided with horizontal positioning legs 11.11' and horizontal fixing air cylinders 12 in order to fix the main body 1 in the slot 51.
will be established. Details of the fixing method will be described later.

A guide rod 14 is attached to one end of the main body 1 on the slot exit side via a bellows or spring universal joint 13 inserted into a retainer, and the main body 1 is moved in and out of the slot.

At the bottom of the main body 1 and the measuring head part 4, legs 15 and 16 are attached which have the function of adjusting the height of the main body. The lower part of the leg 15 is T-shaped, and the main body 1 can be kept horizontal by aligning the horizontal bars of the T-shape in the horizontal direction. Since the legs 16 are short and difficult to adjust in height, the main body 1 can be adjusted by preparing a number of legs with different lengths and replacing the legs 16 every time a certain horizontal potential difference distribution is measured. Adjust the height. Specifically, it is preferable to prepare legs for each measurement pitch in the vertical direction.

A U-shaped member 2 is horizontally attached to one end of the F-lead side of the main body 1, and two guide rods 3 are provided inside thereof in the horizontal direction. A T-shaped measuring head 4, which can be slid horizontally along the guide rod, is mounted laterally and fixed with screws 5. There are two air cylinders 6 at the top and bottom of the measuring head 4.
．． 6' is installed horizontally toward the F lead 50.

A measurement head 7 made of a nonconductor is attached to the tips of the shafts of two air cylinders, and the measurement head 7 can be pressed against the F lead by feeding compressed air into the air cylinders.

The structure of the measuring head 7 is shown in FIGS. 3 and 4.

FIG. 3 is a cross-sectional view, and terminals are inserted into four horizontal holes. The shape of the terminal is a two-stage cylinder with a cone-shaped tip. A coil spring is placed behind the stepped part at the tip to allow it to move in a direction perpendicular to the surface of the F lead 5o, and by pressing it a certain amount, the contact resistance between the terminal and the F lead can be measured. This is to ensure that it does not affect the The terminals include a pair of power supply terminals and a pair of measurement terminals at both ends of the measurement head in the horizontal direction. Measurement terminal 9. Attach the measurement terminal 9' and the power supply terminal 8' vertically in this order. The horizontal spacing between such terminal rows is half the width of the F lead to be measured, or the distance from the side of the F lead to the first measurement position is subtracted from half the width of the F lead. The two screws at the top and bottom of the center are used to attach the driving air cylinder 6, 6' to the shaft. Here, the reason why the measuring head 7 has a stepped tip is because the lower end of the F lead 5o is bent in the horizontal direction, as shown in FIG. This is to create a shape that looks like a match.

FIG. 5 shows the structure around the measuring head portion 4', which has a slightly different shape from that shown in FIG. The measurement head shown in FIG. 1 is for measuring the potential difference above a point slightly lower than the bending starting point of the F lead 5o. Furthermore,
Even if an attempt is made to measure the downward potential difference with the measuring head 7 as shown in FIG. 1, the corner of the measuring head hits the F lead and cannot be measured. Therefore, the shape of the measuring head section 4' is
As shown in the figure, the measuring head 7' can be pushed diagonally downward. In this case, there is one air cylinder 6 for driving the measuring head, and in order to prevent the measuring head 7' from rotating, a guide 10 is attached to the measuring head 7' so that it can move along the hole made in the measuring head part 4'. Make it.

FIG. 6 shows a system diagram of the control, drive, and measurement system of the generator inspection device 1. 20 is a computer, 21 is a CRT for displaying measurement results and data processing results, 22 is an external storage device such as a hard disk for storing data and programs, and 23 is a printer for outputting measurement results and data processing results. It is. The computer 20 controls electromagnetic valves and measuring instruments via the interface 24 and the GP-IB interface 25, takes in measured values, processes them, and outputs the results. The width direction fixing cylinder 12 for fixing to the F lead of the generator inspection device 1 and the measuring head drive cylinder 6.6' are each connected to the compressed air source 26 through a solenoid valve 27.28. is controlled by computer 20 via interface 24. The polarity of the DC current from the DC power source 29 is switched at regular intervals by a current polarity converter 30 controlled by the computer 20 and then supplied to the multiplexer 31, and is further supplied to the power supply terminals 8, 8 of the measurement head to which the current is supplied.
The potential difference between the two measurement terminals 9 and 9' in the horizontal direction is determined by the multiplexer 33.
The measurement terminal to be measured is switched by the , and the measurement terminal is connected to the minute potentiometer 32 and measured. In addition, the main body 1 is connected to the F lead 50 by bare contact so that the potential difference between the F lead 50 and the power supply terminal 9' can also be measured, and
Connect the lead wire drawn from the power supply terminal 9' to the multiplexer 33.
Connect to. This means that when the main body 1 is inserted into the slot, the position is not known, but by measuring the potential difference between the main body 1 and the power supply terminal 9', when the potential difference becomes zero, the power supply terminal 9' is connected to the F lead. 50, the measured potential difference is sent to the computer 2 via the GP-IB interface 25.
Transferred to 0. The computer 20 determines the size of the crack from the potential difference distribution of the F lead using a method described later. Here, the multiplexer 31゜33 and the minute potentiometer 32
is controlled by the computer 20 via the GP-IB interface 25 or the interface 24.

Next, a method for inspecting the F lead of one generator will be described. 7th
The figure shows a flowchart of the inspection. When you start the test,
In step (1), initial settings of the inspection device 1 are performed. In step (2), the inspection device 1 is inserted into the slot of the generator F lead. In step (3), as described above, by measuring the potential difference between the main body 1 and the power supply terminal 9',
Confirm that the power supply terminal 9' has contacted the F lead 50.

At this time, the width direction fixing cylinder 12 is kept in a retracted state, and after confirming that the power supply terminal 9' has contacted the F lead 50, the width direction fixing cylinder 12 is driven to move the inspection device 1 to the slot side wall. Fixed to. Step (5)
The measuring head driving cylinder 6 is driven by the measuring head 7.
is pressed against the surface of the F lead 50, and the potential difference distribution is measured in step (5). The details will be described later. Step (6
), the measuring head driving cylinder 6 is retracted, and in step (8), the width direction fixing cylinder 12 is retracted. In step (9), it is determined whether or not the measurement in the width direction has been completed. 8
If g determination has not been completed, take out the inspection device 1 from the slot in step (11) and proceed to step (12).
Loosen the screw 5 for fixing the measuring head 4, move it in the width direction by the measurement pitch, and fix it again. If the measurement in the width direction has been completed in step (9), it is determined in step (10) whether all measurements have been completed, and if not, in step (13), the inspection device 1 Then, in step (14), the measuring head section 4 is moved to the origin, and the potential difference is measured again.

This procedure is repeated until the measurement of the potential difference distribution at the inspection target portion of the F lead is completed.

The overall flowchart of defect shape detection by measuring potential difference distribution is shown in FIG. 8. In step (21), the potential difference distribution is measured according to the flowchart as shown in FIG.

In step (22), the vertical potential difference distribution of F is determined, and in step (23), the average value of the remaining potential differences excluding the maximum and minimum values in the potential difference distribution is determined, and this is set as the reference potential difference Vo. , in step (24), the distribution of the potential difference ratio V/Vo is determined. In step (25), the coordinate position in the vertical direction where the maximum potential difference ratio is obtained is determined from the potential difference ratio distribution, and the defect position is determined from the connection in the horizontal direction.

In this case, the maximum potential difference ratio at each position in the width direction is 1.0
If it is 2 or more, it is determined that there is a crack, but if it is connected in the width direction within the measurement pitch in the vertical direction, it is considered as one crack. In that case, the distribution of the maximum potential difference ratio connected in the width direction is changed to the potential difference ratio distribution along the crack in step (26).
) Determine the defect shape using the simple surface crack shape determination method described below. Then, the shape of the defect determined in step (27) is output.

Next, the flowchart of potential difference measurement is shown in FIG. 9, and in step (31), the number of measurements at the measurement position where the F lead is located is initialized as J=O. In step (32), the multiplexer 31 is set so that current is supplied to the left power supply terminal of the two left and right measurement terminal rows. Step (
33), the number of potential difference measurements is initialized as n-0. In step (34), the potential difference V+ when ten currents are passed is measured. In step (35), the polarity of the current is switched by the current polarity converter 3°. In step (36), the potential difference V- when ten currents are passed is measured.

In step (37), the polarity of the current is switched and ten currents are caused to flow. In step (38), add 1 to the number of potential difference measurements n to make n=n+1.0 Normally, if you want to accurately measure the potential difference, it is best to measure n about 10 times and evaluate the average value. good. Therefore, in step (39), it is checked whether the number of measurements n has reached 10 times or not.
If the count has not reached 0, repeat the measurement further. n
If the number of times has reached 10, it is checked in step (40) whether the potential difference measurement value is normal or not according to the method described later. If the measured value is abnormal, proceed to step (4).
2) will be re-measured. If the measured value is normal, in step (41) it is checked by the number of measurements J whether the potential difference between the left and right terminals has been measured. If J is not 1, 1 is added to J in step (43) to make J=J+1. In step (44), the multiplexer 31 is set so that current is supplied to the right power supply terminal. Next, step (3
Perform steps 3) to 41 to measure the potential difference at the right measurement terminal.

FIG. 10 shows a flowchart for determining whether a measured potential difference value is normal or abnormal. In step (5o), the potential difference is measured according to the procedure from step (33) to step (41) in FIG. In step (51), the amplitude of the potential difference is determined by dividing the difference between the potential difference V(+) when a positive current flows and the potential difference V(-) when a negative current flows. That is, Vi=V(+)-■(-) is calculated. Step (
In 52), the maximum potential difference, the second potential difference from the maximum, and the minimum potential difference, the second potential difference from the minimum are first deleted as measurement abnormalities. In step (53), the average value of the remaining six potential differences is determined by Vm=ΣVi/6.

Step (54) calculates the standard deviation σ, and step (
55), it is checked whether the standard deviation σ is smaller than 0.5 μV, and if σ≦0.5 μV, the potential difference measurement value is determined to be normal. If σ>0.5 μV, the measured potential difference value is determined to be abnormal, and re-measurement is performed in step (56). In this case, it is considered that there is a poor contact between the power supply terminal and the measurement terminal, so in step (57), the measurement head driving cylinder 6 is driven by the solenoid valve 28 to move the measurement head 6 backward, and in step (58), the measurement head is retracted. , the measuring head is pressed again, and the potential difference is measured again in step (50). Follow the same steps below.

The reason why this potential difference measurement is evaluated based on the amplitude of two measurements, one when the polarity of the current is switched and a positive current is passed and another when a negative current is passed, is because the sample to be measured has some temperature distribution. , a thermoelectromotive force is generated between the measurement terminal and the sample to be measured, and this is included in the measured potential difference as an average potential difference. Therefore, in order to measure the potential difference of the sample to be measured itself, the thermoelectromotive force must be removed by some method. One method is to subtract the potential difference measured when the current is turned off from the potential difference measured when the current is applied. Another method involves intermittently switching the polarity of a direct current and measuring the amplitude of the potential difference. In the latter case, the absolute value of the measured potential difference is larger, so the measurement accuracy is improved accordingly. Also.

The disadvantage of the method of cutting off the current is that it takes time for the current to stabilize after flowing, but the method of switching the polarity of the current has the advantage that the current stabilizes instantly. A device for switching the polarity of this current is a current polarity converting device 30.

A method for determining the shape of a crack from the potential difference distribution of the obtained F lead will be described below. FIG. 11 shows a schematic diagram of the potential difference distribution in the width direction at a certain height using the current difference distribution obtained in step (22) of FIG.

In the measuring head shown in FIG. 1, since the distance between the power supply terminals is short, an edge effect appears near the end face of the lead, the current density becomes high, and the potential difference V becomes large. At the center of the lead, the potential difference ■ is fairly constant. Since such a potential difference distribution is measured for each measurement pitch in the longitudinal direction of the lead, for example, when determining the potential difference distribution in the lead axial direction when become. If there is no crack, the potential difference V remains at a fairly constant value, but at the crack, the potential difference V increases in accordance with the depth of the crack. In the case of FIG. 12, the potential difference at the position indicated by the broken line circle is larger than at other locations. Normally, there are measurement fluctuations in the potential difference, so the reference potential difference vO is set as the average of the potential differences at all locations except for the maximum potential difference at the part where a crack is thought to exist, and the ratio to that, that is, the potential difference ratio V
/V o is larger than 1.02, for example,
It is determined that there is a crack there. FIG. 13 shows a schematic diagram of the distribution of the maximum potential difference ratio determined from the potential difference ratio distribution in the longitudinal direction of the lead at each position in the width direction of the lead. The hatched part is the potential difference ratio V/V.

is larger than 1.02, and it is determined that there is a crack. Next, the connection in the width direction of the leads will be considered in the distribution of the maximum potential difference ratio. If the points with the maximum potential difference ratio are connected in the width direction of the lead, it is determined that the measurements were taken continuously along the crack, and as shown in the figure, the longitudinal direction of the lead is If they are connected within one measurement pitch, it is determined that the measurements were taken continuously along the crack. Then, for example, the potential difference ratio distribution of the location shown by the solid line in FIG. 13 is determined, including the potential difference ratio of the location where the crack is determined to exist and the potential difference ratio in front of the location. A schematic diagram thereof is shown in FIG. The horizontal axis is the width direction of the lead, and the vertical axis is the potential difference ratio. Here, the potential difference ratio distribution of the crack part is approximated by an n-dimensional equation, and the coordinates of the tip of the crack on the surface of the measurement object are determined from the intersection of the approximated curve and the potential difference ratio V/Vo = 1.0. 1. Find the crack length 2c on the surface. Also, from the approximate curve, the maximum potential difference ratio V/V
Find omax.

The method for determining the crack shape from the potential difference distribution along the crack is shown below.
As shown in the figure. Various aspect ratios, for example, a/c = 1.0°0.5, 0, 25, are determined in advance by a general-purpose large-scale computer.
, 0.1, and the potential difference distribution on the surface in the direction perpendicular to the box is stored in the storage device of the computer 20 or the external storage device 22. The potential difference distribution to be stored is the potential difference in the direction perpendicular to the crack on the surface of one member, and these potential difference distributions are stored in the computer 20 as a database in the form of an n-th approximation.
To determine the crack shape, first calculate the surface crack length 2c and the maximum potential difference ratio V/Vomax from the measured potential difference distribution around the crack using the method described above. Find the crack length 2c at the surface from the intersection with the potential difference V/Vo.
In order to create a relationship between the potential difference ratio V/Vo and the crack depth a/t for cracks with various aspect ratios a/c from the potential difference distribution stored in the computer 20 as a database, the potential difference ratio V/Vo and 7 are calculated. Create the relationship of spectral ratio a/c. In this case, in the electric field analysis using FEM, a flat plate with a thickness t of 20 m is analyzed, so the measurement position d corresponding to the distance d between the measurement terminals is
Potential difference ratio V/V o and aspect ratio a/
Therefore, the plate thickness of the member to be measured is corrected by the umbrella (1 umbrella = d
/Create the relationship between Vo and aspect ratio a/c. The relationship between the potential difference ratio V/Vo and the aspect ratio a/C is determined by computer 2o by approximating each crack depth a/to the nth order.
is stored in the storage device 22 of. Next, the potential difference ratio V/Vo
Using the relationship between the aspect ratio a/c and the aspect ratio a/c = 0, 5, the potential difference ratio V/
Create a master curve for the relationship between Vo and crack depth a/t. In this case as well, the relationship between the potential difference ratio V/Vo and the crack depth a/t is approximated to the nth order, for example, to the fifth order.

By substituting the maximum potential difference ratio V/Vomax obtained by n-th approximation of the potential difference distribution into this master curve, the crack depth a・
seek. Next, the surface crack length 2c*(
=2cX20/l), the aspect ratio of the crack is a・/C
Find $ and compare it with the aspect ratio a/c of the master curve.

If the two do not match, the potential difference ratio V/Vo
Using the relationship between the aspect ratio a/c and the aspect ratio a/c, create a master curve of the relationship between the potential difference ratio V/Vo and the crack depth a/t for the aspect ratio a/c:=a fist/cm, and calculate the maximum potential difference ratio V/Vomax. Find the crack depth by substituting . Continue this process until both parties agree, for example, a/
Repeat until the difference between c and a umbrella/C- becomes 0.01 or less, and when they match, the potential difference ratio V/
The shape of the entire crack is determined by substituting the potential difference ratio at each measurement position into the master curve of the relationship between V o and the crack depth a/l. In this case, the potential difference ratio may be substituted with the potential difference ratio at each measurement position, or an n-th approximation of the potential difference ratio distribution may be substituted, and the surface crack shape obtained in this way and the actual crack shape It has been confirmed that they match very well.

FIGS. 16 and 17 show another embodiment. In FIG. 1, there is no mechanism for driving the leads of the measurement head 4 in the width direction, and the inspection device body is taken out of the slot every time the potential difference is measured. Loosen the screw 5 and move the measuring head part in the width direction by hand. In FIG. 16, in order to automate this process, as shown in FIGS. 18 and 19, the guide rod 3' provided on the measuring head support 2 is a screw, and a worm gear 43 is fitted to the guide rod 3'. Install. A small stepping motor 41 is arranged on the upper part of the measuring head section 4, and a worm 42 is attached to the shaft thereof, and the worm 42 and a worm gear 43
so that they fit together. In this way, every time the potential difference between the two sets of measurement terminals provided at both the left and right ends of the measurement head 7 is measured, the stepping motor 41 is driven under the control of the computer 2o to automatically measure the potential difference in the lead width direction. It becomes possible to measure the potential difference distribution. FIG. 20 is a system diagram of the inspection apparatus as shown in FIGS. 16 and 17. The width direction drive motor 41 is connected to and controlled by the computer 20 via the motor drive unit W45 and the interface 24.

FIG. 21 shows a flowchart of measurement in the inspection apparatus shown in FIGS. 16, 17, and 20. When the inspection starts, in step (61), the inspection device 1. In step (62), the inspection device 1 is inserted into the slot of the generator F lead. As described above in step (63), it is confirmed that the power supply terminal 9' has contacted the F lead 50 by measuring the potential difference between the main body 1 and the power supply terminal 9'. At this time, the width direction fixing cylinder 1
2 is in the retracted state, and the power supply terminal 9' is connected to FI
After confirming that it has come into contact with the J-dore 50, the width direction fixing cylinder 12 is driven to fix the inspection device 1 to the slot side wall. In step (65), the measuring head driving cylinder 6 is driven to press the measuring head 7 against the surface of the F lead 50, and in step (66), the potential difference distribution is measured. The method for measuring the potential difference distribution is as described above. Step (6
At step 7), the measuring head driving cylinder 6 is retracted. Check whether the width direction measurement has been completed in step (68), and if the measurement has not been completed, proceed to step (70).
Then, in step (65), the measurement head drive motor 41 is driven to move the measurement head in the width direction by the measurement pitch.
Returning to step (66), the measuring head driving cylinder 6 is driven again to press the measuring head 7 against the surface of the F lead 5o, and the potential difference distribution is measured in step (66). After repeating this and completing the measurement in the width direction in step (68), it is determined in step (69) whether all measurements have been completed, and if not, in step (71), The measurement head drive motor 41 is driven to move the measurement head portion to the origin. Then, in step (72), the width direction fixing cylinder 12 is retracted, and in step (73), the inspection device 1 is taken out from the generator slot. Step (74)
The height of the inspection device 1 is adjusted in step (62), and the inspection device is inserted into the generator slot again in step (62) to measure the potential difference. This procedure is repeated until the measurement of the potential difference distribution at the part to be inspected on the F lead is completed.In this way, the time required for loading and unloading the inspection device and adjusting the position in the width direction is greatly reduced, reducing the overall inspection time. This leads to time savings.

〔Effect of the invention〕

According to the present invention, since the position and shape of a crack can be detected using a simple surface crack shape determination method, a generator lead can be inspected with high accuracy.

[Brief explanation of the drawing]

1 and 2 are a front view and a plan view of a generator inspection device according to an embodiment of the present invention, FIGS. 3 and 4 are a sectional view and a front view of a measuring head, and FIG. 5 is a measuring head section. Figure 6 is a block diagram of the generator inspection device, Figures 7 to 10 are flowcharts of the method for measuring potential difference distribution,
Figures 11 to 15 are diagrams showing a method for determining the crack shape from the measured potential difference distribution, and Figures 16 to 21 are structural diagrams and system diagrams of generator inspection equipment according to other embodiments of the present invention. It is. 1... Generator inspection device, 2... Measurement head support part,
3... Guide rod, 4... Measuring head section, 5... Fixing screw, 6... Air cylinder for driving measuring head, 7...
... Measuring head, 8... Power supply terminal, 9... Measuring terminal, 12... Air cylinder for fixing in the width direction, 2o... Computer, 21... CRT, 22... External storage device, 24...Interface, 25...GP-IB
Interface, 29... DC power supply, 3o... Current polarity converter, 31 Fig. 4 Fig. Iθ Fig. 7 Flowchart of measurement Fig. 9 Flowchart of potential difference measurement Fig. 8 Flowchart of defect shape detection by potential difference distribution measurement Figure 10: Potential difference measurement value determination subroutine flowchart No. 11
Figure 12 Distribution of potential difference in lead width direction Figure 12 Flowchart of surface crack shape determination method Figure 19 Figure Flowchart of measurement

Claims (1)

[Claims] 1. Applying a direct current to the surface of the member through a pair of power supply terminals spaced apart from each other, and measuring the potential difference by providing a pair of potential difference measuring terminals between the pair of power supply terminals; In the turbine generator F lead defect inspection device that detects defects from the potential difference, the rectangular parallelepiped-shaped main body has legs whose height can be adjusted;
A fixing leg for fixing the main body to the slot side wall and an air cylinder for fixing in the width direction are provided, and a spring type or bellows type flexible joint and a guide are provided at one end of the main body via a retainer. A rod is attached, a U-shaped member is attached to another end of the main body, guide rods are provided at two places on the member, and a T-shaped measuring head portion that is slidable laterally along the guide rod is provided. Installation: Air cylinders are attached to the measuring head at two locations, upper and lower, the measuring head is attached to the tip of the piston of the air cylinder, and a pair of power supply terminals and a pair of measuring terminals are attached to both ends of the measuring head. A generator inspection device characterized by being installed. 2. In claim 1, there are provided two DC power supplies for supplying current to the power supply terminal of the measurement head, a current polarity converter for switching the polarity of the current, and air for fixing the device. a compressed air source for driving a cylinder and an air cylinder for driving the measuring head; a solenoid valve; a computer and an interface for controlling the current polarity conversion device and the solenoid valve;
a minute potentiometer for measuring a potential difference; a multiplexer for switching a measurement terminal to be measured; a GP-IB interface for controlling the minute potentiometer and the multiplexer and transmitting the measured potential difference to a computer; CR for monitoring the measurement status and displaying the results of determining the shape of the crack from the measured potential difference distribution
1. A generator inspection device comprising: a T, a printer, and a storage device for storing a measured potential difference distribution. 3. In claim 1 or 2, one of the guide rods attached to the U-shaped member provided at one end of the main body is a screw, and a worm gear is passed through the screw,
A generator inspection device characterized in that a worm is attached to the shaft of a motor attached to the measuring head so as to fit with the worm gear, so that the measuring head can be driven laterally. 4. In claim 1 or 2, one of the guide rods attached to the U-shaped member provided at one end of the main body is a rack, and the shaft of the motor attached to the measuring head section is A generator inspection device characterized in that a pinion is attached so as to fit with the rack so that the measurement head can be driven laterally. 5. A generator inspection device according to claim 1, 2, 3, or 4, characterized in that it is capable of measuring a potential difference between the main body and the terminal. 6. In claim 1, 2, 3, 4 or 5, the length of the leg for height adjustment provided at the lower part of the measuring head section is set to a plurality of lengths for each measurement pitch interval. A generator inspection device characterized by: 7. The generator inspection device according to claim 2, characterized in that one DC power supply is provided, and the multiplexer for switching the current supply destination switches and supplies current to two sets of left and right power supply terminals. . 8. Patent claims 1, 2, 3, 4, and 5
The generator according to item 1, 6 or 7, wherein an air cylinder for driving the measurement head is provided in the measurement head part so as to face diagonally downward, and the measurement head is attached to the shaft end of the air cylinder. Inspection equipment. 9. In patent claims 1 to 8, the potential difference is measured several times by switching the polarity of the current, the amplitude at the time of switching is calculated, and the potential difference amplitude is obtained by excluding the upper and lower limits of the calculated value. If the standard deviation is larger than 0.5 μV, it is determined that the measurement is abnormal, and the head is moved back once and then pressed again to measure the potential difference again. , the standard deviation of the potential difference measurements is 0.
A generator inspection device characterized in that a measurement value smaller than 5μV is adopted as a normal measurement value. 10. According to claims 1 to 9, the measurement head is moved in the lateral direction of the lead part to measure the potential difference distribution, the legs are sequentially replaced to measure the potential difference distribution across the lead part, and the Find the vertical potential difference distribution of the lead part from the potential difference distribution, calculate the average value by excluding the upper and lower limits, use this average value as the reference potential difference to find the vertical potential difference ratio distribution, and then calculate the maximum potential difference. A generator inspection device characterized by determining a ratio, determining a horizontally connected distribution of the maximum potential difference ratio, and determining a crack shape from the maximum potential difference ratio distribution.