Insulator ceramics with good insulating properties, heat resistance, flexibility and assembly, etc., are widely used in the voltage level of the transmission line.Insulator ceramics with the increase of operating years, its insulation performance will be decreased, and deterioration gradually exposed defects.Coupled with long-term exposure to running in the field, under the effect of natural disasters, lightning, dirty, etc., when the transmission line of ceramics Insulator string out the phenomenon have occurred, threatening the safe operation of power grid.Today to find out cause of the accident off the string and precautions.
First, the cause of the accident analysis
1.External main reason
Fault line trip time of day for the thunderstorm, tower attachment failure have lightning activity, lightning location system integrated analysis of Insulator Flashover from lightning can be seen off the string Insulator suffered a lightning strike.The lightning failure and geographical environment, tower height, the insulation level of several factors related to the analysis, it was found 110kVN61 tower on a hilltop, before and after the span larger (respectively 485m and 525m), so the tower becomes easy to hit the spot.Further, high resistance ground fault of the tower, after the measured value exceeded the design value 15Q, which can easily cause a lightning failure;
2.Internal reasons
Insulator strings away from the ceramic to see the inner cap and the steel surface of the steel with a corrosion and foot traces of discharge, the value is zero, instructions, low Ceramic Insulator.Were tested, a zero value and a low value found Insulator ceramics, most of the insulation resistance of the MQ only a dozen, performance does not meet the operational requirements.
When mixing a zero value, a low value series ceramic Insulator Ceramic Insulator of being struck by lightning, a lightning strike occurs the high potential, and a zero value, this part of the weak low Ceramic Insulator breakdown, a large short-circuit current flows through the high temperature inside Insulator , the internal temperature of the ceramic heated rapidly vaporize the moisture contained Insulator explosive power, so that some difference in the mechanical strength of the steel cap of string burst accident occurs;
3.The reason Ceramic Insulator steel cap burst of
Design of the mechanical strength of the ceramic suspension are steel legs Insulator breaking strength as control points, however, the running string and out Insulator view, have not found a phenomenon steel legs broken ring.Steel cap poor material, sandwiched impurities in the wire vibration years of long-term irregular, may gradually expand into small cracks (difficult to find during operation), under the action of external lightning harsh environments, it may lead to cracking of the steel cap.Burst out from the string of steel Insulator cap sandwiched impurities found fracture mouth, there burst at the old and new cracks.One reason is the poor material Description steel cap steel cap running Insulator burst accident.
Second, preventive measures
1.Strict accordance with procedures prescribed cycle ceramics Insulator detection, timely replacement of zero, low Insulator;
2.Grounding by means buried deep enough, corrosion, contact failure, and other causes of high soil resistivity mainly the resistance grounding system, resulting in lead mine is not smooth, and therefore regularly tower grounding resistance is measured in accordance with the rules of order, grounding resistance failure of the tower in a timely manner and network transformation, in particular, should catch up before the storm season coming, raise the level of mine-resistant line;
3.Ceramic Insulator sampling tests performed strictly testing system, test load, etc., for electrical and mechanical damage;
4.Easy to install lightning strike point line arresters, vulnerable to lightning tower are: prominent hilltop, near the pond reservoir; a high tower sections or high tower sunny slope; high ground slope at the brink of the waters high resistance tower; large span a large span of the tower, whereby these tower sections should add line lightning arresters prone, lightning damage occurs when the effective protection Insulator.
These are the swap for Ceramic Insulator string causes and preventive measures related Introduction.From the above it is easy to see the reason of String Insulator ceramics are diverse, and therefore attach great importance to its dangers, timely monitoring, reduce the number of Ceramics Insulator string out.
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