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Method for detecting dielectric liquid level in closed porcelain cover through ultrasonic non-interventive method

A dielectric liquid, non-intervention technology, applied in the direction of liquid/fluid solid measurement, measuring device, liquid level indicator, etc., can solve the problems of unstable signal, change of electric field distribution, easy misjudgment, etc., and achieve simple and convenient operation , high detection sensitivity, no pollution to the environment

Active Publication Date: 2016-07-27
SHAANXI NORMAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the insulating oil in the porcelain bushing will reduce the liquid level due to oil leakage, and the low oil level will lead to changes in the electric field distribution and even breakdown accidents, so the oil level must be monitored frequently online
Since the online porcelain sleeve is a closed container, the general interventional level gauge cannot be applied; the non-interventional externally mounted liquid level gauge cannot be placed due to the large number of umbrellas outside the porcelain sleeve
Related to the present invention, the method for solving this problem mainly contains two kinds at present: one is to utilize ultrasonic wave to detect the oil level in the ceramic bushing at ceramic / air interface and ceramic / oil interface acoustic impedance difference (comparative document 1: application number is 201310628787.1 published patent), but this difference is easily affected by surface coupling, changes in the wall thickness of the porcelain sleeve, after-vibration interference in the wall of the porcelain sleeve, nonlinearity of the transducer, etc., making the signal unstable and prone to misjudgment, and even cover up this in severe cases. A difference that can't even be achieved
Another method (comparison document 2, published patent with application number 201310473564.2) is to use a detection system composed of two probes to compare reflectivity changes and then determine the liquid level. The disadvantage of this method is that it needs to use two probes, and online detection is not easy to control

Method used

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  • Method for detecting dielectric liquid level in closed porcelain cover through ultrasonic non-interventive method
  • Method for detecting dielectric liquid level in closed porcelain cover through ultrasonic non-interventive method
  • Method for detecting dielectric liquid level in closed porcelain cover through ultrasonic non-interventive method

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Embodiment 1

[0024] In this embodiment, a 110KV ceramic sleeve oil-filled outdoor terminal is taken as an example. The sound velocity of the wall material is 6850m / s. The ultrasonic non-interventional method for detecting the oil level in the sealed porcelain sleeve consists of the following steps:

[0025] (1) Adjust the baseline ratio and scanning range when the digital flaw detector is horizontal, so that the baseline display range is at least the maximum thickness of the porcelain casing, and adjust the working frequency of the flaw detector to 5MHz.

[0026] In this embodiment, the Hanwei HS620 digital ultrasonic flaw detector produced by Wuhan Zhongke is used, the operating frequency (0.5-20MHz), the sound velocity range (100-20000) m / s, the pulse intensity 600V; the attenuator accuracy <+1dB / 12dDB; The maximum gain is 110dB. The probe in this embodiment is a 7.5 MHz Φ10 longitudinal wave straight probe, and the chip length is 6 mm.

[0027] (2) Divide the control sleeve that has no...

Embodiment 2

[0031] The probe of this embodiment is a straight longitudinal wave probe of 1.25MHzΦ10, the chip length is 4mm, and the wall material with a sound velocity of 5960m / s is selected for use.

[0032] In order to ensure that the fitted control curve is more accurate, in step (2) of this embodiment, the control porcelain sleeve that has not been injected with a dielectric liquid medium is divided into the upper section, the middle section and the lower section, and 2 points are respectively taken on each section as At the detection point, apply a small amount of couplant to couple the probe to the recessed side wall between two adjacent sheds outside the porcelain sleeve; first couple the probe to the detection point 1 of the upper section, and the probe is directed into the wall of the porcelain sleeve Ultrasonic waves are emitted, and the sound waves propagating in the wall of the porcelain sleeve are reflected at the solid / gas interface. The reflected echoes are received by the ...

Embodiment 3

[0036] The probe of this embodiment selects the longitudinal wave small-angle probe of 10MHzΦ10, its angle is 8 degrees, the chip length is 8mm, and selects the wall material sound velocity to be the ceramic cover of 7530m / s, and its size is identical with embodiment 1.

[0037] Other steps are identical with embodiment 1 or 2.

[0038] In the actual detection process, due to the aging of the dielectric liquid in the porcelain sleeve to be tested, the peak of the first interface echo obtained at the point to be tested may fall on the solid / air interface distance-amplitude curve or the solid / liquid interface distance- The position adjacent to the bottom of the amplitude curve is a reasonable error and does not affect the judgment of the test result.

[0039] The ceramic bushing of the present invention can be selected from the standard porcelain bushing whose sound velocity ranges from 5000 to 8000m / s. Well, the frequency and chip size of the detection probe can also be adapti...

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Abstract

The invention relates to a method for detecting a dielectric liquid level in a closed porcelain cover through an ultrasonic non-interventive method. The method comprises the steps that before a comparison porcelain cover is filled with dielectric liquid media, first interface echo wave crests on all detecting points on the side walls of an upper section, a middle section and a lower section are collected, a solid and gas interface distance-wave amplitude curve is drawn, after the comparison porcelain cover is filled with the dielectric liquid media, the first interface echo wave crests on the detecting points are collected, a solid and liquid interface distance-wave amplitude curve is drawn, the first interface echo wave crests collected on the porcelain cover to be detected is compared with those of the curve, and therefore the dielectric liquid level is determined. According to the method for detecting the dielectric liquid level in the closed porcelain cover through the ultrasonic non-interventive method, it is guaranteed that all the positions of the porcelain cover have the same detection sensitivity, the detection sensitivity is high, measurement errors caused by probe coupling, porcelain cover external diameter change, probe nonlinearity and the like are eliminated, the reliability and consistency of detection are high, liquid is not leaked, the environment is not polluted, and the method is suitable for detection of the liquid levels in various closed porcelain covers.

Description

technical field [0001] The invention belongs to the technical field of detecting the liquid level of a dielectric liquid in a closed porcelain sleeve, and in particular relates to a method for detecting the liquid level of a dielectric liquid in a closed porcelain sleeve by using an ultrasonic non-intervention method. Background technique [0002] At present, many cable terminals in substations are insulated with oil-filled porcelain bushings. However, the insulating oil in the porcelain bushing will reduce the liquid level due to oil leakage. Too low oil level will lead to changes in the electric field distribution and even breakdown accidents. Therefore, the oil level must be monitored frequently online. Since the online porcelain sleeve is a closed container, the general invasive liquid level gauge cannot be applied; the non-interventional externally mounted liquid level gauge cannot be placed due to the large number of umbrellas outside the porcelain sleeve. Related to ...

Claims

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Application Information

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IPC IPC(8): G01F23/296
CPCG01F23/296
Inventor 莫润阳祁宏昌梁双龙王成会
Owner SHAANXI NORMAL UNIV
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