The relationship between the high voltage insulator
polluted degree parameter in high voltage insulator pollution flashover mechanism analysis, is represented by fouling layer surface conductivity of uncleanness, and this shows that the unclean surface layer yuan electrical conductivity and lightning pressure are essentially linked, through the dirt layer surface conductivity parameter set up a variety of filth degrees inner link.
Local surface conductivity)
, and the overall relationship between the surface conductivity numerous due to the high voltage insulator metal accessories and there is an air space between the porcelain, causing fouling layer, the factors causing the overall small mouth surface conductivity of actual measured value, and there is a great deal of dispersion.
If can completely eliminate the dirt layer continuously, the influence of such factors as the mouth value will be equal and Y values.
Local surface conductivity)
, and the operating voltage of the * big leakage current Ih through theoretical derivation, the relationship between y and operating voltage can be obtained under the * the relationship between the large leakage current/n 2 L (
Y a stool each In—
Is a worker.
/ suspension type high voltage insulator, U representative operating voltage;
/ on behalf of the high voltage insulator leakage distance.
Local surface conductivity and equivalent salt density S y.
Through a lot of artificial contamination test, the relationship between the statistics that the relationship of y -
The experiment was conducted on artificial contamination test local surface conductivity measurement results obtained.
Mentioned in the discussion of the equivalent amount of salt in dense, filth of artificial contamination test parameters & ndash;
Salt fouling lightning pressure extruding and the correlation of good, natural polluted polluted degree parameters of high voltage insulator & ndash;
Salt fouling lightning pressure extruding and correlation is bad;
Two kinds of salt is not a concept, the main difference is that the composition of soluble salt in the dirt.
Composition of soluble salt in artificial contamination contamination is NaCl, natural impurity composition of soluble salt in the complex, may be the main component is the bivalent salt poorly soluble in water, if you can translate the natural filthy salt density into artificial contamination of salt, salt, or called effective can and lightning pressure develop direct contact.
One possible way is filth on the natural chemical composition analysis, according to the proportion of monovalent salts and bivalent salts to convert, but the cost of this method is too big, difficult to operate.
Gives another way to solve the problem of train of thought, as long as the measured out natural filthy try the partial surface conductivity y, according to the type (
Can be measured out)
Converted to Sd, values, click here to get hold of Sa to avoid the big water dissolve dirt measurement method, the defects caused by the filth of the sample (s) represents the real degree.
Impulse voltage under the action of high voltage insulator pollution flashover mechanism of filth high-voltage insulator under the effect of lightning impulse voltage or operation of the dielectric strength, compared with the clean high voltage insulator, also has considerable reduced.
Therefore, under the influence of lightning impulse voltage or operation, also has the problem of pollution flashover.
Under normal circumstances, the pollution flashover accident is mainly refers to the flashover accident under the operating voltage, the flashover caused by lightning overvoltage and operating overvoltage accident and few meteorological conditions causing pollution flashover, so often overlooked defile the influencing factors.
For wet dirt under the condition of the mechanism of the decrease of strength of high voltage insulator impulse voltage, there is no consistent view and conclusion.
Test results show that the dirty wet condition, the operation of the impulse voltage insulation for low intensity than clean be affected with damp be affected with damp condition.
Using different test method to obtain the results vary widely, for example, some test results show that the state of wet sludge has influence to the lightning impulse voltage, some experimental results, no impact.
Several typical test results is briefly as follows.
The dirty lightning impulse voltage under pressure and decreased with the increase of the impurity level, the size is associated with high voltage insulator type and degree of filth.
Impurity distribution also has effect on the dielectric strength of the under impulse voltage, uneven impurity distribution than uniform filthy dielectric strength lower, in the dirt conditions may also be affected with damp be affected with damp, and about 17% less.
At this point, the filthy impact the operation of high voltage insulator flashover voltage value is about communication impurity peak voltage of about 2 times.
Also some test shows that under the condition of moderate uncleanness, the operation of high voltage insulator impact resistance strength will be higher than the clean damp resistance values, even under heavy impurity only falling down little or no.
This feature is considered to be due to the effect of impulse voltage operation time is not enough to the dry zone is formed on the high voltage insulator show, or how much wet dirt layer to improve the voltage distribution along the high voltage insulator string.
Test there is no additive ac voltage under impulse voltage insulation strength have a significant impact.
In filth on the high voltage insulator impulse voltage, only does not reflect the actual operation of the high voltage insulator.
Practice is, in addition to some special cases, filthy high-voltage insulator under the working voltage for a long time, due to the heating effect of the leakage current, dry area had formed in high voltage insulator surface, the out of work and the long-term effect of high voltage insulator surface state, the extra impulse voltage, high voltage insulator flashover process is different.
For filthy high voltage insulator, therefore, should be on the basis of the long time working voltage function superposition impulse voltage to test again to conform to the actual situation.
On a message: partial composite insulator surface fouling layer conductivity measurement 】
A message: under high voltage insulator measuring method and contrast of uncleanness, and measure the equivalent composite insulator salt density 】
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