1. A glass insulator crack extraction system, the system comprising:

and the driving positioning mechanism is used for controlling the surrounding shooting platform above the driving positioning mechanism to reach the position of the transmission line of each glass insulator based on the navigation position of each glass insulator stored in the built-in storage unit.

2. The glass insulator crack extraction system of claim 1, wherein:

the driving positioning mechanism comprises a storage unit, a navigation unit and a driving unit, wherein the driving unit is respectively connected with the storage unit and the navigation unit.

3. The glass insulator crack extraction system of claim 2, further comprising:

the surrounding shooting platform is arranged above the running positioning mechanism and used for performing surrounding shooting operation on the current glass insulator to obtain a plurality of acquisition pictures at different visual angles on the same level and splicing the acquisition pictures at different visual angles to obtain a panoramic acquisition picture;

the first-layer processing mechanism is connected with the surrounding shooting platform and used for executing image data enhancement processing of applying logarithmic transformation on the received panoramic acquisition picture so as to obtain a corresponding first-layer processing picture;

the sublayer processing mechanism is connected with the first-layer processing mechanism and is used for carrying out image data sharpening processing of applying Kirsch operators on the received first-layer processed picture so as to obtain a corresponding sublayer processed picture;

the point-by-point checking mechanism is connected with the sublayer processing mechanism and is used for obtaining each gray value of each pixel in the sublayer processing picture and taking the pixel of which the absolute value of the difference value between the gray value and the gray reference value of the surrounding pixels exceeds a preset difference threshold value as a crack pixel;

the replacement prompting mechanism is connected with the point-by-point inspection mechanism and used for sending a replacement request instruction when the number of the crack pixels in the secondary processing picture exceeds the limit, and sending a replacement-free instruction when the number of the crack pixels in the secondary processing picture does not exceed the limit;

the mobile communication mechanism is respectively connected with the replacement prompting mechanism and the driving positioning mechanism and is used for marking a replacement request instruction and positioning information provided by the driving positioning mechanism into a single IP data packet to be wirelessly sent to a remote power facility maintenance server when receiving the replacement request instruction;

wherein, regarding a pixel, as a crack pixel, of which an absolute value of a difference between the gray value and the gray reference value of the surrounding pixels exceeds a preset difference threshold, the method includes: acquiring all gray values of all surrounding pixels, sorting the gray values, and taking the gray value of the middle serial number as a gray reference value of the surrounding pixels;

the mobile communication mechanism is also used for not executing wireless transmission of the IP data packet to a remote power facility maintenance server when receiving the replacement-free instruction;

the surrounding shooting platform comprises a horizontal disc body, a mounting seat, a direct current motor, a vertical bar body and a photoelectric sensor, wherein the photoelectric sensor is arranged at the top of the vertical bar body, and the horizontal disc body is arranged above the running positioning mechanism;

the mounting seat is arranged in an annular groove body in the horizontal disc body, and the direct current motor is used for driving the mounting seat to rotate around the central position of the horizontal disc body in the annular groove body.

4. The glass insulator crack extraction system of claim 3, wherein:

erect on the mount pad the body of rod of erectting for drive erect the body of rod and carry out the annular and remove, photoelectric sensor sets up erect the top of the body of rod for carry out surrounding type shooting operation to current glass insulator, in order to obtain a plurality of collection pictures of different visual angles on the same level.

5. The glass insulator crack extraction system of claim 4, wherein:

the surround shooting platform further comprises signal combination equipment which is connected with the photoelectric sensor and used for splicing the received multiple collected pictures at different visual angles to obtain a panoramic collected picture.

6. A glass insulator crack extraction method is characterized by comprising the following steps:

and the driving positioning mechanism is used for controlling the surrounding shooting platform above the driving positioning mechanism to reach the position of the transmission line of each glass insulator based on the navigation position of each glass insulator stored in the built-in storage unit.

7. The method for extracting cracks from a glass insulator according to claim 6, wherein:

the driving positioning mechanism comprises a storage unit, a navigation unit and a driving unit, wherein the driving unit is respectively connected with the storage unit and the navigation unit.

8. The glass insulator crack extraction method of claim 7, further comprising:

the method comprises the steps that a surrounding shooting platform is used, is arranged above a running positioning mechanism and is used for performing surrounding shooting operation on a current glass insulator to obtain a plurality of collecting pictures at different visual angles on the same level, and the collecting pictures at the different visual angles are spliced to obtain a panoramic collecting picture;

the first-layer processing mechanism is connected with the surrounding shooting platform and used for executing image data enhancement processing of applying logarithmic transformation on the received panoramic acquisition picture so as to obtain a corresponding first-layer processing picture;

using a secondary layer processing mechanism which is connected with the primary layer processing mechanism and used for carrying out image data sharpening processing of applying Kirsch operators on the received primary layer processing picture so as to obtain a corresponding secondary layer processing picture;

using a point-by-point checking mechanism, connecting with the sub-layer processing mechanism, and obtaining each gray value of each pixel in the sub-layer processing picture, and using the pixel of which the absolute value of the difference value between the gray value and the gray reference value of the surrounding pixels exceeds a preset difference threshold value as a crack pixel;

the replacing prompting mechanism is connected with the point-by-point inspection mechanism and used for sending a replacing request instruction when the number of the crack pixels in the secondary processing picture exceeds the limit, and sending a replacement-free instruction when the number of the crack pixels in the secondary processing picture does not exceed the limit;

the mobile communication mechanism is respectively connected with the replacement prompting mechanism and the driving positioning mechanism and used for marking a replacement request instruction and positioning information provided by the driving positioning mechanism into a single IP data packet to be wirelessly sent to a remote power facility maintenance server when the replacement request instruction is received;

wherein, regarding a pixel, as a crack pixel, of which an absolute value of a difference between the gray value and the gray reference value of the surrounding pixels exceeds a preset difference threshold, the method includes: acquiring all gray values of all surrounding pixels, sorting the gray values, and taking the gray value of the middle serial number as a gray reference value of the surrounding pixels;

the mobile communication mechanism is also used for not executing wireless transmission of the IP data packet to a remote power facility maintenance server when receiving the replacement-free instruction;

the surrounding shooting platform comprises a horizontal disc body, a mounting seat, a direct current motor, a vertical bar body and a photoelectric sensor, wherein the photoelectric sensor is arranged at the top of the vertical bar body, and the horizontal disc body is arranged above the running positioning mechanism;

the mounting seat is arranged in an annular groove body in the horizontal disc body, and the direct current motor is used for driving the mounting seat to rotate around the central position of the horizontal disc body in the annular groove body.

9. The method for extracting cracks from a glass insulator according to claim 8, wherein:

erect on the mount pad the body of rod of erectting for drive erect the body of rod and carry out the annular and remove, photoelectric sensor sets up erect the top of the body of rod for carry out surrounding type shooting operation to current glass insulator, in order to obtain a plurality of collection pictures of different visual angles on the same level.

10. The method for extracting cracks from a glass insulator according to claim 9, wherein:

the surround shooting platform further comprises signal combination equipment which is connected with the photoelectric sensor and used for splicing the received multiple collected pictures at different visual angles to obtain a panoramic collected picture.

Background

In the first few years of production and operation, the glass insulator is found to have a series of advantages over the porcelain insulator as follows:

the surface of the glass insulator has high mechanical strength, so that the probability of surface fracture is reduced; the electrical strength of glass generally remains constant throughout the entire operating period and its ageing process is much slower than that of porcelain, so that glass insulators are mainly scrapped due to self-damage and occur within the first year of operation, whereas porcelain insulators have defects which only begin to be discovered after a few years of operation;

by adopting the glass insulator, the live periodical preventive test of the insulator in the running process can be cancelled; the reason is that each kind of damage of the toughened glass can cause the damage of the insulator, and operators can easily find the damage when patrolling the line; when the insulator is damaged, the glass fragments near the steel cap and the iron foot are clamped, and the mechanical strength of the rest part of the insulator is enough to prevent the insulator string from breaking; the self-breaking rate of the glass insulator is one of important indexes for measuring the quality of products and is also a quality basis for evaluating the standard when the current transmission engineering calls and puts into operation.

At present, the surface cracks of the glass insulator are shallow, the surface cracks are difficult to identify or the surface cracks of the glass insulator are difficult to identify completely by adopting a manual detection mode or a general electronic detection mode, meanwhile, the glass insulator is generally used for a high-voltage transmission line, and the manual detection mode is difficult to unfold and the detection rate is low due to the high-voltage detection environment.

Disclosure of Invention

In order to solve the technical problems in the prior art, the invention provides a glass insulator crack extraction system and a glass insulator crack extraction method, which can complete whole visual data acquisition of each glass insulator on a purposefully designed hardware platform, and realize detection of the crack propagation degree of the current glass insulator on the basis of the whole visual data acquisition, so that key data is provided for whether to replace the glass insulator.

For this reason, the present invention needs to have at least the following important points:

(1) a running positioning mechanism comprising a storage unit, a navigation unit and a running unit and a surrounding shooting platform comprising a horizontal disc body, a mounting seat, a direct current motor, a vertical rod body and a photoelectric sensor are introduced, so that the whole visual data acquisition of each glass insulator is realized;

(2) and obtaining each gray value of each pixel in the field picture processed in a targeted manner, and taking the pixel of which the absolute value of the difference value between the gray value and the gray reference value of the surrounding pixels exceeds a preset difference threshold value as a crack pixel so as to send a replacement request instruction when the number of the crack pixels in the secondary processing picture exceeds the limit.

According to an aspect of the present invention, there is provided a glass insulator crack extraction system, the system comprising:

and the driving positioning mechanism is used for controlling the surrounding shooting platform above the driving positioning mechanism to reach the position of the transmission line of each glass insulator based on the navigation position of each glass insulator stored in the built-in storage unit.

More specifically, in the glass insulator crack extraction system:

the driving positioning mechanism comprises a storage unit, a navigation unit and a driving unit, wherein the driving unit is respectively connected with the storage unit and the navigation unit.

More specifically, in the glass insulator crack extraction system, further comprising:

the surrounding shooting platform is arranged above the running positioning mechanism and used for performing surrounding shooting operation on the current glass insulator to obtain a plurality of acquisition pictures at different visual angles on the same level and splicing the acquisition pictures at different visual angles to obtain a panoramic acquisition picture;

the first-layer processing mechanism is connected with the surrounding shooting platform and used for executing image data enhancement processing of applying logarithmic transformation on the received panoramic acquisition picture so as to obtain a corresponding first-layer processing picture;

the sublayer processing mechanism is connected with the first-layer processing mechanism and is used for carrying out image data sharpening processing of applying Kirsch operators on the received first-layer processed picture so as to obtain a corresponding sublayer processed picture;

the point-by-point checking mechanism is connected with the sublayer processing mechanism and is used for obtaining each gray value of each pixel in the sublayer processing picture and taking the pixel of which the absolute value of the difference value between the gray value and the gray reference value of the surrounding pixels exceeds a preset difference threshold value as a crack pixel;

the replacement prompting mechanism is connected with the point-by-point inspection mechanism and used for sending a replacement request instruction when the number of the crack pixels in the secondary processing picture exceeds the limit, and sending a replacement-free instruction when the number of the crack pixels in the secondary processing picture does not exceed the limit;

the mobile communication mechanism is respectively connected with the replacement prompting mechanism and the driving positioning mechanism and is used for marking a replacement request instruction and positioning information provided by the driving positioning mechanism into a single IP data packet to be wirelessly sent to a remote power facility maintenance server when receiving the replacement request instruction;

wherein, regarding a pixel, as a crack pixel, of which an absolute value of a difference between the gray value and the gray reference value of the surrounding pixels exceeds a preset difference threshold, the method includes: acquiring all gray values of all surrounding pixels, sorting the gray values, and taking the gray value of the middle serial number as a gray reference value of the surrounding pixels;

the mobile communication mechanism is also used for not executing wireless transmission of the IP data packet to a remote power facility maintenance server when receiving the replacement-free instruction;

the surrounding shooting platform comprises a horizontal disc body, a mounting seat, a direct current motor, a vertical bar body and a photoelectric sensor, wherein the photoelectric sensor is arranged at the top of the vertical bar body, and the horizontal disc body is arranged above the running positioning mechanism;

the mounting seat is arranged in an annular groove body in the horizontal disc body, and the direct current motor is used for driving the mounting seat to rotate around the central position of the horizontal disc body in the annular groove body.

According to another aspect of the present invention, there is also provided a glass insulator crack extraction method, the method including:

and the driving positioning mechanism is used for controlling the surrounding shooting platform above the driving positioning mechanism to reach the position of the transmission line of each glass insulator based on the navigation position of each glass insulator stored in the built-in storage unit.

More specifically, in the glass insulator crack extraction method:

the driving positioning mechanism comprises a storage unit, a navigation unit and a driving unit, wherein the driving unit is respectively connected with the storage unit and the navigation unit.

More specifically, in the method for extracting cracks from a glass insulator, the method further comprises:

the method comprises the steps that a surrounding shooting platform is used, is arranged above a running positioning mechanism and is used for performing surrounding shooting operation on a current glass insulator to obtain a plurality of collecting pictures at different visual angles on the same level, and the collecting pictures at the different visual angles are spliced to obtain a panoramic collecting picture;

the first-layer processing mechanism is connected with the surrounding shooting platform and used for executing image data enhancement processing of applying logarithmic transformation on the received panoramic acquisition picture so as to obtain a corresponding first-layer processing picture;

using a secondary layer processing mechanism which is connected with the primary layer processing mechanism and used for carrying out image data sharpening processing of applying Kirsch operators on the received primary layer processing picture so as to obtain a corresponding secondary layer processing picture;

using a point-by-point checking mechanism, connecting with the sub-layer processing mechanism, and obtaining each gray value of each pixel in the sub-layer processing picture, and using the pixel of which the absolute value of the difference value between the gray value and the gray reference value of the surrounding pixels exceeds a preset difference threshold value as a crack pixel;

the replacing prompting mechanism is connected with the point-by-point inspection mechanism and used for sending a replacing request instruction when the number of the crack pixels in the secondary processing picture exceeds the limit, and sending a replacement-free instruction when the number of the crack pixels in the secondary processing picture does not exceed the limit;

the mobile communication mechanism is respectively connected with the replacement prompting mechanism and the driving positioning mechanism and used for marking a replacement request instruction and positioning information provided by the driving positioning mechanism into a single IP data packet to be wirelessly sent to a remote power facility maintenance server when the replacement request instruction is received;

wherein, regarding a pixel, as a crack pixel, of which an absolute value of a difference between the gray value and the gray reference value of the surrounding pixels exceeds a preset difference threshold, the method includes: acquiring all gray values of all surrounding pixels, sorting the gray values, and taking the gray value of the middle serial number as a gray reference value of the surrounding pixels;

the mobile communication mechanism is also used for not executing wireless transmission of the IP data packet to a remote power facility maintenance server when receiving the replacement-free instruction;

the surrounding shooting platform comprises a horizontal disc body, a mounting seat, a direct current motor, a vertical bar body and a photoelectric sensor, wherein the photoelectric sensor is arranged at the top of the vertical bar body, and the horizontal disc body is arranged above the running positioning mechanism;

the mounting seat is arranged in an annular groove body in the horizontal disc body, and the direct current motor is used for driving the mounting seat to rotate around the central position of the horizontal disc body in the annular groove body.

The glass insulator crack extraction system and method provided by the invention are compact in structure and reliable in logic. The crack propagation degree detection of each glass insulator can be completed on the basis of a purposefully designed hardware platform and a purposefully designed crack identification mechanism, so that the original manual detection mode is effectively replaced.

Brief description of the drawings

The numerous advantages of the present invention may be better understood by those skilled in the art by reference to the accompanying drawings in which:

fig. 1 is a schematic structural diagram of a glass insulator to which the glass insulator crack extraction system and method according to the present invention are applied.

Detailed Description

A device for supporting and insulating a wire is called an insulator, and the insulator device is made of glass and called a glass insulator; the most widely used in the line at present is the toughened glass insulator. The insulator is generally made of glass or porcelain.

Insulators are used mainly to fix wires to electric poles and the like and to insulate the wires from the electric poles and the like. The insulator is one of the key parts of the high-voltage transmission line, and the performance of the insulator directly influences the operation safety of the whole transmission line. The glass insulator is widely applied due to the characteristics of zero value self-breaking, easy maintenance and the like.

At present, the surface cracks of the glass insulator are shallow, the surface cracks are difficult to identify or the surface cracks of the glass insulator are difficult to identify completely by adopting a manual detection mode or a general electronic detection mode, meanwhile, the glass insulator is generally used for a high-voltage transmission line, and the manual detection mode is difficult to unfold and the detection rate is low due to the high-voltage detection environment.

The present invention will now be described in detail with respect to the disclosed subject matter.

Fig. 1 is a schematic structural diagram of a glass insulator to which the glass insulator crack extraction system and method according to the present invention are applied.

In fig. 1, 1 is a first layer shed of the glass insulator, 2 is a second layer shed of the glass insulator, and 3 is a main structure of the glass insulator.

The glass insulator crack extraction system shown according to the embodiment of the invention comprises:

and the driving positioning mechanism is used for controlling the surrounding shooting platform above the driving positioning mechanism to reach the position of the transmission line of each glass insulator based on the navigation position of each glass insulator stored in the built-in storage unit.

Next, a specific configuration of the glass insulator crack extraction system according to the present invention will be further described.

In the glass insulator crack extraction system:

the driving positioning mechanism comprises a storage unit, a navigation unit and a driving unit, wherein the driving unit is respectively connected with the storage unit and the navigation unit.

The glass insulator crack extraction system can further comprise:

the surrounding shooting platform is arranged above the running positioning mechanism and used for performing surrounding shooting operation on the current glass insulator to obtain a plurality of acquisition pictures at different visual angles on the same level and splicing the acquisition pictures at different visual angles to obtain a panoramic acquisition picture;

the first-layer processing mechanism is connected with the surrounding shooting platform and used for executing image data enhancement processing of applying logarithmic transformation on the received panoramic acquisition picture so as to obtain a corresponding first-layer processing picture;

the sublayer processing mechanism is connected with the first-layer processing mechanism and is used for carrying out image data sharpening processing of applying Kirsch operators on the received first-layer processed picture so as to obtain a corresponding sublayer processed picture;

the point-by-point checking mechanism is connected with the sublayer processing mechanism and is used for obtaining each gray value of each pixel in the sublayer processing picture and taking the pixel of which the absolute value of the difference value between the gray value and the gray reference value of the surrounding pixels exceeds a preset difference threshold value as a crack pixel;

the replacement prompting mechanism is connected with the point-by-point inspection mechanism and used for sending a replacement request instruction when the number of the crack pixels in the secondary processing picture exceeds the limit, and sending a replacement-free instruction when the number of the crack pixels in the secondary processing picture does not exceed the limit;

the mobile communication mechanism is respectively connected with the replacement prompting mechanism and the driving positioning mechanism and is used for marking a replacement request instruction and positioning information provided by the driving positioning mechanism into a single IP data packet to be wirelessly sent to a remote power facility maintenance server when receiving the replacement request instruction;

wherein, regarding a pixel, as a crack pixel, of which an absolute value of a difference between the gray value and the gray reference value of the surrounding pixels exceeds a preset difference threshold, the method includes: acquiring all gray values of all surrounding pixels, sorting the gray values, and taking the gray value of the middle serial number as a gray reference value of the surrounding pixels;

the mobile communication mechanism is also used for not executing wireless transmission of the IP data packet to a remote power facility maintenance server when receiving the replacement-free instruction;

the surrounding shooting platform comprises a horizontal disc body, a mounting seat, a direct current motor, a vertical bar body and a photoelectric sensor, wherein the photoelectric sensor is arranged at the top of the vertical bar body, and the horizontal disc body is arranged above the running positioning mechanism;

the mounting seat is arranged in an annular groove body in the horizontal disc body, and the direct current motor is used for driving the mounting seat to rotate around the central position of the horizontal disc body in the annular groove body.

In the glass insulator crack extraction system:

erect on the mount pad the body of rod of erectting for drive erect the body of rod and carry out the annular and remove, photoelectric sensor sets up erect the top of the body of rod for carry out surrounding type shooting operation to current glass insulator, in order to obtain a plurality of collection pictures of different visual angles on the same level.

In the glass insulator crack extraction system:

the surround shooting platform further comprises signal combination equipment which is connected with the photoelectric sensor and used for splicing the received multiple collected pictures at different visual angles to obtain a panoramic collected picture.

The glass insulator crack extraction method shown according to the embodiment of the invention comprises the following steps:

and the driving positioning mechanism is used for controlling the surrounding shooting platform above the driving positioning mechanism to reach the position of the transmission line of each glass insulator based on the navigation position of each glass insulator stored in the built-in storage unit.

Next, the specific steps of the method for extracting cracks from a glass insulator according to the present invention will be further described.

The glass insulator crack extraction method comprises the following steps:

the driving positioning mechanism comprises a storage unit, a navigation unit and a driving unit, wherein the driving unit is respectively connected with the storage unit and the navigation unit.

The glass insulator crack extraction method can further comprise the following steps:

the method comprises the steps that a surrounding shooting platform is used, is arranged above a running positioning mechanism and is used for performing surrounding shooting operation on a current glass insulator to obtain a plurality of collecting pictures at different visual angles on the same level, and the collecting pictures at the different visual angles are spliced to obtain a panoramic collecting picture;

the first-layer processing mechanism is connected with the surrounding shooting platform and used for executing image data enhancement processing of applying logarithmic transformation on the received panoramic acquisition picture so as to obtain a corresponding first-layer processing picture;

using a secondary layer processing mechanism which is connected with the primary layer processing mechanism and used for carrying out image data sharpening processing of applying Kirsch operators on the received primary layer processing picture so as to obtain a corresponding secondary layer processing picture;

using a point-by-point checking mechanism, connecting with the sub-layer processing mechanism, and obtaining each gray value of each pixel in the sub-layer processing picture, and using the pixel of which the absolute value of the difference value between the gray value and the gray reference value of the surrounding pixels exceeds a preset difference threshold value as a crack pixel;

the replacing prompting mechanism is connected with the point-by-point inspection mechanism and used for sending a replacing request instruction when the number of the crack pixels in the secondary processing picture exceeds the limit, and sending a replacement-free instruction when the number of the crack pixels in the secondary processing picture does not exceed the limit;

the mobile communication mechanism is respectively connected with the replacement prompting mechanism and the driving positioning mechanism and used for marking a replacement request instruction and positioning information provided by the driving positioning mechanism into a single IP data packet to be wirelessly sent to a remote power facility maintenance server when the replacement request instruction is received;

wherein, regarding a pixel, as a crack pixel, of which an absolute value of a difference between the gray value and the gray reference value of the surrounding pixels exceeds a preset difference threshold, the method includes: acquiring all gray values of all surrounding pixels, sorting the gray values, and taking the gray value of the middle serial number as a gray reference value of the surrounding pixels;

the mobile communication mechanism is also used for not executing wireless transmission of the IP data packet to a remote power facility maintenance server when receiving the replacement-free instruction;

the surrounding shooting platform comprises a horizontal disc body, a mounting seat, a direct current motor, a vertical bar body and a photoelectric sensor, wherein the photoelectric sensor is arranged at the top of the vertical bar body, and the horizontal disc body is arranged above the running positioning mechanism;

the mounting seat is arranged in an annular groove body in the horizontal disc body, and the direct current motor is used for driving the mounting seat to rotate around the central position of the horizontal disc body in the annular groove body.

The glass insulator crack extraction method comprises the following steps:

erect on the mount pad the body of rod of erectting for drive erect the body of rod and carry out the annular and remove, photoelectric sensor sets up erect the top of the body of rod for carry out surrounding type shooting operation to current glass insulator, in order to obtain a plurality of collection pictures of different visual angles on the same level.

The glass insulator crack extraction method comprises the following steps:

the surround shooting platform further comprises signal combination equipment which is connected with the photoelectric sensor and used for splicing the received multiple collected pictures at different visual angles to obtain a panoramic collected picture.

The insulation resistance of the glass insulator was measured as follows: in the single-element insulator, the insulation resistance can be measured only under the condition of power failure, the related regulations stipulate that 2500V or more megohmmeters are adopted, 2500V and 5000V megohmmeters are frequently used at present, and special instruments with higher voltage are also adopted, but actually, within 1 x 104M omega, the 2500V and 5000V megohmmeters with the same precision are basically the same in the insulation resistance measured under the same humidity, and when the measured insulation resistance is more than 1 x 104M omega, the 2500V megohmmeter can not read out the accurate insulation resistance value and only can count according to infinity. The maximum insulation resistance of 5000 megohm meter can reach 2 x 105M omega.

Meanwhile, for the multi-element combined insulator, the insulation resistance can be measured in a power failure or live way, the method is that a high resistance is connected to the live insulator, a megohmmeter for measuring the insulation resistance is positioned at the ground potential, the resistance value of the high resistance is subtracted from the measured insulation resistance, namely the insulation resistance value of the measured insulator, the principle wiring of the insulation resistance of the live measuring insulator is adopted, R is the resistance in a high resistance rod, the resistance value is selected according to 10-20 k omega/V and the length is selected according to 0.5-105 kV/cm, and the capacity of each unit of resistance is l-2W; c is a grounding capacitor, so that the megohmmeter can be positioned at the ground potential, the insulation resistance of the C should reach the maximum limit of the megohmmeter so as to ensure the accuracy of measurement, and the capacitance of the C is 0.01-0.05 muF and can bear the direct-current voltage of more than 3000V.

As certain changes could be made in the above without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a literal sense. Those skilled in the art will appreciate that the sequence of steps or structures illustrated in the figures may be varied without departing from the scope of the invention, and that the illustrations contained herein are merely individual examples of the many possible descriptions of the invention.