Dry transformer coil defect detecting method

Abstract

The invention discloses a detection method of dry-typed transformer coil-defect which is capable of effectively detecting the defects in dry-typed transformer coils. The detection method is realized by the following technical proposal of: firstly cleaning the inner and the outer surfaces of the transformer coil, and then fixing the transformer coil on a clamping frame which can do positive and negative rotary motions; coating engine oil or syrup on two floating-type ultrasonic probes as well as between the inner and the outer surfaces of the coil to be detected as coupling agent; then leading the transformer coil to do positive and negative rotary motions for less than 360 degrees at the uniform rotation speed of 60-80 circles per minute, and simultaneously leading the two floating-type ultrasonic probes to do walking scanning motions on the inner and the outer surfaces of the coil along the axial direction of the coil at the speed of 0.4-0.6 meters per minute; simultaneously, recording the defective waveform by an ultrasonic instrument at any time, and analyzing to obtain the defect sizes and the positions thereof; and wiping all the exposed surfaces of the coil clean after the completion of the detection.

Description

technical field [0001] The invention relates to a detection method for a coil defect of a dry-type transformer, that is to say, it provides an effective and practical detection method for the detection of a coil defect of a high-voltage dry-type transformer. Background technique [0002] The production of high-voltage dry-type transformer coils generally adopts the traditional winding and pouring epoxy resin process, and a layer of epoxy resin is wrapped outside the copper wire layer of the coil. Two types of defects are easily formed in this layer during pouring: one is The pouring is loose, because the liquid epoxy resin is not fully fed during the cooling and solidification shrinkage process, resulting in the formation of very fine irregular scattered or dense cavities; the other type is epoxy resin and transformer coil copper wire The junction of the inner and outer walls of the layer is easy to form unfused defects similar to welding. Since the temperature of the trans...

AI Technical Summary

Problems solved by technology

[0002] The production of high-voltage dry-type transformer coils generally adopts the traditional winding and pouring epoxy resin process, and a layer of epoxy resin is wrapped outside the copper wire layer of the coil. Two types of defects are easily formed in this layer during pouring: one is The pouring is loose, because the liquid epoxy resin is not fully fed during the cooling and solidification shrinkage process, resulting in the formation of very fine irregular scattered or dense cavities; the other type is epoxy resin and transformer coil copper wire The junction of the inner and outer walls of the layer is easy to form unfused defects similar to welding

Since the temperature of the transformer is high when it is working, and it returns to normal temperature when it is not working, the defects will develop into fatigue cracks due to the frequent influence of cold and heat, which will easily cause water seepage or damp, which will affect the insulation performance of the coil, thereby making the transformer invalid and causing accidents.

Therefore, the defect detection of the coil should be carried out in time to avoid and repair such defects, but there is no method for detecting the defect of the high-voltage dry-type transformer coil. Therefore, it is necessary to provide an effective and practical method for detecting the defect of the dry-type transformer coil method

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