CN110618160B - Magnetic resonance sensor for aging detection of cable insulation layer material - Google Patents
Magnetic resonance sensor for aging detection of cable insulation layer material Download PDFInfo
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- CN110618160B CN110618160B CN201911071682.4A CN201911071682A CN110618160B CN 110618160 B CN110618160 B CN 110618160B CN 201911071682 A CN201911071682 A CN 201911071682A CN 110618160 B CN110618160 B CN 110618160B
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- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N24/00—Investigating or analyzing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects
- G01N24/08—Investigating or analyzing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects by using nuclear magnetic resonance
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Abstract
The invention relates to a magnetic resonance sensor for detecting aging of a cable insulating layer material, and belongs to the field of measuring instruments. The magnetic resonance sensor comprises a permanent magnet mechanism and a radio frequency coil mechanism; the permanent magnetic mechanism is used for establishing a horizontal static magnetic field along the axial direction in the insulating rubber on the surface of the cable; the radio frequency coil mechanism is used for establishing a radio frequency magnetic field vertical to the static magnetic field in the cable surface insulating rubber; the permanent magnet mechanism is vertically connected with the radio frequency coil mechanism. When in measurement, the whole sensor is moved along the axial direction of the cable for measurement. The invention solves the problem that the aging of the outer insulating layer material of the cable cannot be measured by the existing dielectric loss tangent method.
Description
Technical Field
The invention belongs to the field of measuring instruments, and relates to a magnetic resonance sensor for detecting aging of a cable insulation layer material.
Background
At present, methods for measuring aging of a cable insulating layer material include a dielectric loss tangent measurement method, a thermal stimulation current method and a Fourier infrared spectroscopy method. When the medium loss tangent method is used for measurement, exciting current needs to be applied between an inner core conductor and an outer shielding conductor of the cable, only the overall insulation performance of the whole cable section can be measured, and the aging condition of the outermost insulation layer of the cable cannot be measured. When the measurement is performed by using a thermal stimulation current method and a Fourier infrared spectroscopy, a sample to be measured needs to be cut into a specified shape, an outer insulating layer of a cable is damaged, and the method belongs to a destructive method and cannot be used on site. So that the power industry is lack of a nondestructive method for evaluating the aging state of the outer insulating layer material of the cable.
Disclosure of Invention
In view of the above, the present invention provides a magnetic resonance sensor for detecting aging of a cable insulation layer material.
In order to achieve the purpose, the invention provides the following technical scheme:
a magnetic resonance sensor for detecting aging of cable insulation layer materials comprises a permanent magnet mechanism and a radio frequency coil mechanism;
the permanent magnetic mechanism is used for establishing a horizontal static magnetic field along the axial direction in the insulating rubber on the surface of the cable;
the radio frequency coil mechanism is used for establishing a radio frequency magnetic field perpendicular to the static magnetic field in the cable surface insulating rubber;
the permanent magnet mechanism is vertically connected with the radio frequency coil mechanism.
Optionally, the permanent magnet mechanism includes a stainless steel core and two permanent magnets;
the stainless steel iron core is U-shaped, and the two permanent magnets are respectively arranged at two ends of the stainless steel iron core;
the two permanent magnets have opposite magnetic poles;
the two permanent magnets are arranged along the axial direction of the cable and used for guiding the static magnetic field trend of the permanent magnets to form a magnetic circuit.
Optionally, the radio frequency coil mechanism includes a radio frequency iron core and a radio frequency solenoid coil;
the radio frequency iron core is triangular and provided with an opening;
the radio frequency helical tube coil is wound at two ends of the opening of the radio frequency iron core;
two terminals are led out from the radio frequency spiral tube coil and are used for being connected with an external measuring circuit.
The invention has the beneficial effects that: the invention solves the problem that the existing dielectric loss tangent method can not measure the aging of the outer insulating layer material of the cable, and the prior art adopts the method of injecting the exciting current to measure, so that the contact resistance exists between the injection electrode and the measured sample material, which can cause the measurement error. The using method of the invention utilizes electromagnetic wave excitation, has no contact resistance with the tested sample, can more accurately provide a measuring result, and can realize nondestructive measurement without cutting the tested sample from the whole cable.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.
Drawings
For the purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:
FIG. 1 is a block diagram of the present invention;
FIG. 2 is a view showing a structure of a permanent magnet mechanism according to the present invention;
FIG. 3 is a diagram of the RF coil mechanism of the present invention;
fig. 4 is an exponential decay curve of the measured CPMG echo signal peak;
FIG. 5 is a CPMG echo signal peak value attenuation curve obtained by fitting;
FIG. 6 shows the transverse relaxation time T of the rubber material 2 A one-dimensional spectral distribution.
Detailed Description
The following embodiments of the present invention are provided by way of specific examples, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and embodiments may be combined with each other without conflict.
Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in the drawings in which there is no intention to limit the invention thereto; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not an indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes, and are not to be construed as limiting the present invention, and the specific meaning of the terms may be understood by those skilled in the art according to specific situations.
Referring to fig. 1 to 3, a magnetic resonance sensor for detecting aging of a cable insulation material includes a permanent magnet mechanism and a radio frequency coil mechanism;
the permanent magnetic mechanism is used for establishing a horizontal static magnetic field along the axial direction in the insulating rubber on the surface of the cable;
the radio frequency coil mechanism is used for establishing a radio frequency magnetic field perpendicular to the static magnetic field in the cable surface insulating rubber;
the permanent magnet mechanism is vertically connected with the radio frequency coil mechanism.
Optionally, the permanent magnet mechanism includes a stainless steel core and two permanent magnets;
the stainless steel iron core is U-shaped, and the two permanent magnets are respectively arranged at two ends of the stainless steel iron core;
the two permanent magnets have opposite magnetic poles;
the two permanent magnets are arranged along the axial direction of the cable and used for guiding the static magnetic field trend of the permanent magnets to form a magnetic circuit.
Optionally, the radio frequency coil mechanism includes a radio frequency iron core and a radio frequency solenoid coil;
the radio frequency iron core is triangular and provided with an opening;
the radio frequency helical tube coil is wound at two ends of the radio frequency iron core opening;
two terminals are led out from the radio frequency spiral tube coil and are used for being connected with an external measuring circuit.
When in measurement, the whole sensor is moved along the axial direction of the cable for measurement.
The nuclear magnetic resonance is a physical phenomenon that the nuclear magnetic moment of a substance generates energy level splitting under the action of an external magnetic field and generates energy level transition under the action of an external radio frequency magnetic field, and the conditions for generating the nuclear magnetic resonance are as follows: angular frequency omega of radio frequency pulse and nuclear magnetic moment winding external magnetic field B 0 Larmor precession angular frequency ω 0 And are equal.
In materials science, nuclear magnetic resonance technology researches the crosslinking density and uniformity of a material by analyzing molecular operation on a macromolecular chain of a rubber material, and low-field nuclear magnetic resonance is used as a powerful nondestructive detection technology and is widely used for measuring the crosslinking density of a polymeric material, controlling the quality of a rubber production process, detecting the aging of the rubber and the macromolecular material, measuring the content of each component in a polymer and the like. Under the influence of severe environment or partial discharge and the like, in the aging process of the insulating rubber material on the surface of the cable, molecular chemical bonds forming the rubber material are broken, and new molecular groups are formed under the action of external environment, so that the number and the combination state of hydrogen nuclei in the whole material are changed, and the nuclear magnetic resonance signals of the hydrogen nuclei in different combination states are different, therefore, the distribution state of the corresponding hydrogen atoms can be analyzed by measuring the corresponding nuclear magnetic resonance relaxation information, and the aging state of the rubber material is further evaluated.
Fig. 4 shows an exponential decay curve of the measured CPMG echo signal peak when a 180 ° Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence is continuously applied to a rubber material, and the function form of the curve can be expressed as:
wherein t = nT echo N is the number of echoes, T echo As echo time, M 0 Is the macroscopic transverse magnetization vector, M, of the sample measured at the initial moment xy (T) amplitude of the echo signal at time T, T 2 Is the transverse relaxation time. The transverse relaxation time T can be determined according to the attenuation curve obtained by fitting the echo signal peak point 2 . The signal attenuation caused by static magnetic field nonuniformity can be reduced by repeatedly applying 180 DEG pulses, and the data sampled at the peak of the signal is not influenced by the magnetic field uniformity. The decay curve is therefore dependent only on the spin-spin interaction of the protons, i.e. on the intrinsic transverse relaxation time of the rubber material, so that the rubber material can be reflected by this curveThe aging state of (c).
Using the designed magnetic resonance sensor, magnetic resonance signal measurement is performed on the rubber material which is just shipped and used for 5 years, and fig. 5 is a CPMG echo signal peak attenuation curve obtained by fitting. It can be seen that the longer the service life of the rubber material, the T 2 The faster the curve decays, i.e. the transverse relaxation time T 2 The smaller.
The obtained CPMG echo signal peak curve is subjected to inverse Laplace transform, so that the transverse relaxation time T of the rubber material shown in FIG. 6 can be obtained 2 One-dimensional spectral distribution, long transverse relaxation time component T due to inverse Laplace transform 2long Maximum amplitude and best repeatability, at T 2 The distribution position on the spectrum is relatively stable, and the rubber material has comparability between different service times. Therefore, the long component T of the transverse relaxation time is used 2long The degree of aging of the silicone rubber material was characterized. As can be seen from FIG. 6, as the service life of the rubber material increases, the degree of aging increases, T 2long Reducing, and therefore measuring, the transverse relaxation time T with the magnetic resonance sensor 2，long The aging degree of the rubber material of the cable insulation layer can be quantitatively evaluated.
Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.
Claims (1)
1. A magnetic resonance sensor for detecting aging of a cable insulation layer material is characterized in that: comprises a permanent magnet mechanism and a radio frequency coil mechanism;
the permanent magnet mechanism is used for establishing a horizontal static magnetic field along the axial direction in the insulating rubber on the surface of the cable;
the radio frequency coil mechanism is used for establishing a radio frequency magnetic field perpendicular to the static magnetic field in the cable surface insulating rubber;
the permanent magnet mechanism is vertically connected with the radio frequency coil mechanism;
the permanent magnet mechanism comprises a stainless steel iron core and two permanent magnets;
the stainless steel iron core is U-shaped, and the two permanent magnets are respectively arranged at two ends of the stainless steel iron core;
the two permanent magnets have opposite magnetic poles;
the two permanent magnets are arranged along the axial direction of the cable and used for guiding the static magnetic field trend of the permanent magnets to form a magnetic circuit;
the radio frequency coil mechanism comprises a radio frequency iron core and a radio frequency helical tube coil;
the radio frequency iron core is triangular and provided with an opening;
the radio frequency helical tube coil is wound at two ends of the opening of the radio frequency iron core;
two terminals are led out from the radio frequency spiral tube coil and are used for being connected with an external measuring circuit;
when a 180 ℃ PMG pulse sequence of a heavy polymerization phase is continuously applied to the insulating rubber, an exponential decay curve of a CPMG echo signal peak value is obtained by measurement, and the function form is expressed as follows:
wherein t = nT echo N is the number of echoes, T echo As echo time, M 0 Is the macroscopic transverse magnetization vector, M, of the sample measured at the initial moment xy (T) is the amplitude of the echo signal at time T, T 2 Is the transverse relaxation time;
determining transverse relaxation time T according to attenuation curve obtained by fitting echo signal peak point 2 (ii) a Reflecting the aging state of the insulating rubber through a curve;
insulating rubber of longer age, T 2 The faster the curve decays, i.e. the transverse relaxation time T 2 The smaller;
carrying out inverse Laplace transformation on the obtained CPMG echo signal peak value curve to obtain transverse relaxation time T of the insulating rubber 2 One-dimensional spectral distribution, using the long component of the transverse relaxation time T 2long Characterizing the aging degree of the silicon insulating rubber; as the service life of the insulating rubber increases, the degree of aging increases, T 2long Reducing the transverse relaxation time T measured by a magnetic resonance sensor 2long And quantitatively evaluating the aging degree of the insulating rubber of the cable insulating layer.
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Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9703018D0 (en) * | 1996-02-23 | 1997-04-02 | Western Atlas Int Inc | Nuclear magnetic resonance apparatus and method |
| JP2005147693A (en) * | 2003-11-11 | 2005-06-09 | Hamano Life Science Research Foundation | Electron spin resonance state measuring device and measuring method |
| CN2749458Y (en) * | 2004-11-29 | 2006-01-04 | 沈阳东软波谱磁共振技术有限公司 | Heating arrangement of permanent-magnet type magnet body for MRI |
| TWM324205U (en) * | 2007-03-02 | 2007-12-21 | Lian-Pin Hwang | Single-sided portable NMR apparatus |
| CN101672904A (en) * | 2009-09-14 | 2010-03-17 | 东南大学 | Probe for portable nuclear magnetic resonance (NMR) vessel detector |
| CN102998323A (en) * | 2012-11-30 | 2013-03-27 | 重庆大学 | Method for evaluating aging degree of crosslinked polyethylene cable based on nuclear magnetic resonance |
| CN104297281A (en) * | 2014-10-24 | 2015-01-21 | 广东电网有限责任公司东莞供电局 | Circular arc unilateral nuclear magnetic resonance sensor |
| CN108776317A (en) * | 2018-06-12 | 2018-11-09 | 重庆大学 | A kind of cylindrical core magnetic resonance probe |
| CN109030532A (en) * | 2018-07-11 | 2018-12-18 | 王黎莉 | A kind of unilateral nuclear magnetic resonance three-dimensional imaging magnet system |
-
2019
- 2019-11-05 CN CN201911071682.4A patent/CN110618160B/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9703018D0 (en) * | 1996-02-23 | 1997-04-02 | Western Atlas Int Inc | Nuclear magnetic resonance apparatus and method |
| JP2005147693A (en) * | 2003-11-11 | 2005-06-09 | Hamano Life Science Research Foundation | Electron spin resonance state measuring device and measuring method |
| CN2749458Y (en) * | 2004-11-29 | 2006-01-04 | 沈阳东软波谱磁共振技术有限公司 | Heating arrangement of permanent-magnet type magnet body for MRI |
| TWM324205U (en) * | 2007-03-02 | 2007-12-21 | Lian-Pin Hwang | Single-sided portable NMR apparatus |
| CN101672904A (en) * | 2009-09-14 | 2010-03-17 | 东南大学 | Probe for portable nuclear magnetic resonance (NMR) vessel detector |
| CN102998323A (en) * | 2012-11-30 | 2013-03-27 | 重庆大学 | Method for evaluating aging degree of crosslinked polyethylene cable based on nuclear magnetic resonance |
| CN104297281A (en) * | 2014-10-24 | 2015-01-21 | 广东电网有限责任公司东莞供电局 | Circular arc unilateral nuclear magnetic resonance sensor |
| CN108776317A (en) * | 2018-06-12 | 2018-11-09 | 重庆大学 | A kind of cylindrical core magnetic resonance probe |
| CN109030532A (en) * | 2018-07-11 | 2018-12-18 | 王黎莉 | A kind of unilateral nuclear magnetic resonance three-dimensional imaging magnet system |
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