Scene from China

PPC Insulators

Characterizing Pollution Severity Needs More than Simply Relying on ESDD

Properly characterizing and measuring the pollution affecting overhead lines and substations is of great importance when specifying insulators to minimize risk of pollution flashover. While there are several relevant parameters to assess pollution severity,... Read More

Coating Insulators with RTV Silicone in the Factory

RTV silicone anti-pollution flashover coatings have been used extensively for years – initially mainly on post insulators and bushings at substations and more recently also for porcelain or glass string insulators on transmission lines. One of the reasons... Read More

Wildfire Hazard to Transmission Lines

HV transmission lines inevitably pass through mountainous areas where forest and brush fires are a constant threat. This has made wildfires an important factor in line trips and outages. Occurrence of wildfires is both regional and seasonal but, as... Read More

Impact of Icing on Transmission Lines

Icing problems can have a severe impact on the safe operation of overhead transmission lines. Early in 2008, for example, extensive icing hit large areas of southern China. The rare but disastrous meteorological conditions led to outages on 119 lines at 500... Read More

Using Less Creepage for Silicone Insulators

Composite insulators are today quite widely used and well-accepted throughout the world. In China, for example, there several million such insulators already in service on HV transmission lines up to 1000 kV AC and ± 800 kV DC. In addition, huge numbers of... Read More

Impact of Lightning on Transmission Lines

In places such as China, lightning accounts for about 60% of all transmission line tripping and is closely linked to season as well as region. Based on physical processes, lightning overvoltages fall into two broad categories: • those caused by direct... Read More

Monitoring Leakage Current to Evaluate Insulator Pollution

Leakage currents flow across the surface of polluted insulators under wet atmospheric conditions and link closely to resulting discharge phenomena. They have a range of characteristics that include maximum amplitude, number of pulses that exceed certain... Read More