High voltage insulator failures precautions

High voltage insulator is a special insulation control, it can play a supporting wire in overhead transmission lines, to prevent the current grounding of the dual role. Insulator for wire and wire receiving portion towers, substations and lines frame joint. Press dielectric insulator material into porcelain type, glass type, composite, three forms. Analysis of common faults and repair high voltage insulator preventive measures, mainly to prevent the environmental and electrical load conditions occur due to various electrical and mechanical stress leads to insulator insulation failure, to the detriment of the use and the operating life of the power line.

Failure Analysis

High voltage insulator perennial exposed to the atmosphere, affected by lightning, filthy, bird damage, snow, heat, cold, elevation and other factors, will lead to the occurrence of accidents.

Lightning accident. Overhead line channels usually hills, mountains, open area and have polluted industrial zone, the line easily struck by lightning induced voltage insulators breakdown or bursting.

Bird damage accident. Research shows that high voltage insulator flashover accident, a considerable part of the damage caused by birds. Bird damage accident, compared to porcelain high voltage insulators, high voltage glass insulators, high voltage composite insulators are more likely to flashover accident. Bird damage caused by high voltage insulator flashover accident occurred in the 110 kV and above transmission lines, 35 kV and Flashover urban distribution network in high-voltage insulators bird damage occurred because fewer. The reason is that relatively few birds within the city, the line voltage itself is not high, less able to penetrate the air gap, without having to install high-voltage insulator grading ring, an umbrella group can effectively prevent bird damage flashover accidents.

Equalizing ring accident. High voltage insulator during operation, near the end of the gold with concentrated electric field distribution, the higher the field strength in the air near the flange, in order to improve the ends of gold with field strength around and above 220 kV grid addition of grading rings. High voltage insulator strings were installed after the pressure ring, reducing the clearance distance from high voltage insulator strings, the pressure level is relatively lower, and because of all the pressure ring bolts at the corona voltage is low, in bad weather conditions, the impact of corona phenomenon a high voltage insulator string of security.

Filthy accident. Filthy accident means accumulated on the insulator surface high pressure line, having conductive properties filthy substance, in wet weather, when wet the insulation levels high voltage insulator greatly reduced, flashover accident in normal operation.

Unexplained. In composite insulator flashover accidents, many accidents are caused by unknown reasons, such as high-voltage porcelain insulators zero value, high voltage insulator glass burst, complex high-voltage insulators tripping. After the accident, although the operating unit organized tour to find, and we did not find a specific reason flashover. This flashover accidents have many common characteristics, most occurred in the middle of the night to the morning, especially in rainy weather, after flashover accident, there are a lot of success but also to automatic reclosing.

Maintenance measures

High voltage insulator flashover lightning strikes mainly dry arc distance is too short, single-ended configuration equalizing ring and ground resistance exceeded. Preventive maintenance should be used in the synthesis of high-voltage insulators lengthened, install double grading ring and lower the tower grounding resistance.

In order to effectively prevent bird damage accident occurred, the unit should be run on a section of line often happens bird damage accident, an additional compartment bird nets, anti-bird pin and install anti-bird enclosures.

For the use of grading rings line should equal the size of the umbrella skirt structure, the distance between the umbrella should meet the technical requirements, the requirements are not met, an additional high-voltage insulator creepage distance, reduce flashover accidents caused by snow and ice. At the same time to strengthen the inspection checks, regular testing in different regions, different environments running high voltage insulator, its tension, electrical and insulation aging test. Prevent strong enough lead to pull guard, anti-swing diminished capacity and flashover accidents caused by aging due sheds occurred.

In order to prevent high voltage insulator contamination flashover, the general should take the following measures:

Regular cleaning high-voltage insulators. Flashover year before the accident-prone season comes, it must conduct a general cleaning high-voltage insulators. In the contamination affected areas should be increased cleaning frequency.

Increase creepage distance, improve the insulation level. Such as increasing the number of high-voltage insulator model piece of polluted areas, or the use of dust high voltage insulator. Operating experience shows that lots of serious contamination, dust-proof high-voltage insulators, antifouling effect is better.

Dust-proof coatings, will be wax, paraffin wax, silicone and other materials applied to the surface of high-voltage insulators, high voltage insulator improve soil resistance.

For unexplained high voltage insulator flashover caused by accident, shall be returned to the manufacturer of high-voltage insulators same model new products and run for more than three years old product were dry flash frequency, mechanical damage and other tests, high voltage insulator for different periods of operation aging testing. Press the test cycle, the high-voltage insulator regular cleaning, timely salt density test new products into the process of adding new measures for anti-aging agent.

In addition, the repair and maintenance process, the prohibition maintenance personnel pedaling or rub with a sharp tool high-voltage insulators, high voltage insulator to prolong life.