Cap and Pin Suspension Porcelain (Glass) Composite Insulator for DC Power System

The series products of ac/dc cap&pin suspension ceramic(glass) composite insulator covers 32 provinces, cities, and autonomous regions, operating on more than 1100 electric transmission and transformation circuits, with more than 360 million pieces safely operating on the electric network since it came to the market 13 years ago. We also work keenly with overseas friends, our products find good sales in South Africa and South Korea.

Advantages of cap and pin suspension porcelain (glass) composite insulator: 

● Excellent pollution flashover resistant performance-the excellent hydrophobicity and hydrophobe mobility of silicon rubber housing increase the power frequency wet flashover voltage and pollution flashover resistance. Through artificial pollution flashover voltage contrast test, it was founded that the pollution flashover voltage of each disc of porcelain (glass) composite insulator was increased by 70% than the same type of porcelain insulator. Meanwhile, the shed design of the product is reasonable, has good self-cleaning capacity to wind and rain, is slow in dirt retention, and especially in dirty environment such as dust, it demonstrates its advantages. This insulator is easy to adjust external insulation creepage distance and can meet the requirements of transmission line in heavy polluted area on the creepage distance of insulators. It can effectively prevent transmission lines from pollution flashover tripping accidents and ensure the safe operation of transmission lines. 

● Stable and reliable mechanical properties-the end connecting fittings (iron cap, steel foot) of this insulator adopt cap and pin porcelain insulator structure, the internal porcelain core disc uses high strength porcelain, glass disc uses toughened glass, so it has high strength after adhesive binding, thus reliably ensure the bearing and transmission of moment acting on the insulator. Test results showed that its mechanical properties were stable and reliable, fully met and even were higher than the standard of porcelain insulators. 

● Small size, light weight, being convenient for transport and maintenance-this series of products has the advantages of small size and light weight. Compared with the porcelain insulator and glass insulator, it can reduce 1/3 weight under same number of discs, thus reducing the installation labor intensity and load-bearing pressure of the iron tower. It can bear the bending moment well in tension string and mitigate the destruction of periodic impulse force on the iron tower. 

● Unique and reasonable structure, easy to replace-in the external structure of porcelain (glass) composite insulator (see attached photo), add a concave slot in the design of iron cap on the basis of original porcelain iron cap, which is easy for tool clamping during insulator replacement. The connection size and structure height of insulator iron cap and steel foot are exactly same with original porcelain insulator, can be used interchangeably, and is very convenient to replace, the porcelain (glass) composite insulator can be replaced directly without adjusting the tower height and sag of original line, which significantly reduces the maintenance workload. 

● Long service life, truly maintenance-free- the porcelain (glass) composite insulator is truly maintenance-free and overhauling-free. Traditional pollution flashover preventing measures are spraying RTV anti-pollution flashover paint on the surface of porcelain insulator, but the spraying work costs much time, labor and money, and need long time power outage, and it should be re-sprayed every 3-5 years. The porcelain (glass) composite insulator can be used for more than 30 years without replacement and need no preventive insulation monitoring test and periodic scheduled power outage for pollution cleaning, which reduce the workload of routine maintenance and the accident probability during line maintenance, and the transmission line can work safely in heavy polluted area. 

Analysis of economic and social benefits:  

●The porcelain (glass) composite insulator has large creepage distance. On condition that ensuring the safe ground clearance and air breakdown safe distance, the increased anti-pollution capacity can reduce the string length through reducing the number of insulators, can lower the tower, which can saving 20% steel and 10% land area, and can effectively solve the insufficient ground clearance during creepage adjustment. Only in reducing the tower height in new line, according to 10,000 kilometers of new 500kV line and 30,000 kilometers of 110 kV, 220 kV and 330 kV line each year, it can save more than 1.7 billion construction funds. 

●Avoid the large amount of power losses of grid enterprises due to power outage for cleaning porcelain bottle and outage losses in industry and agriculture. 

●Solve the problem that the repair and maintenance personnel are difficult to maintain the porcelain bottle due to inconvenient traffic, high mountains and other adverse conditions.

●Avoid personal accident during line maintenance work. 

●Reduce the huge personnel and fund input during later maintenance and lower the operating cost. Only the one advantage that insulator is maintenance-free, according to 10,000 kilometers each year: can save maintenance costs of 26,880,000 Yuan for 500kV line and 12,680,000 Yuan for 220kV line. 

●No longer carry on zero value porcelain bottle check and no longer be embarrassed for glass bottle spontaneous explosion.

●It can save investments by more than 3 times in 20 years! Benefits can not be pondered by the money.