Cement Growth Failure of Porcelain Suspension Insulators

Accelerating aging of transmission line porcelain suspension insulators by autoclaving

“…One type of failure of ceramic suspension insulators in Korea is the fracture failure of the porcelain by aging deterioration or transient stress. This is a well known phenomenon reported in other countries [1,2].…”

“…In previous research, there is no simulation of mechanical load with cement displacement [2,5]. But in this study both are simulated.…”

Porcelain insulation – defining the underlying mechanism of failure

“…Wet conditions can result in cement growth (expansion), a phenomena explained in [24,25] as attributing to high failure rates of suspension insulators. In their research, radial cracks in two piece cap and pin insulators caused by expanding cement paste resulted in 30-90% reductions in mechanical strength leading to insulator parting and line dropping.…”

“…Heat played a role in the expansion process as well. The authors [24,25] describe how some intact insulators were found to be internally stressed (mechanically) and only fractured upon application of heat. Their findings stated that the temperature required to fracture porcelain was >216°C.…”

Microstructure based evaluation of field aged and new porcelain suspension insulators

“…It is used in the neat form or as a mortar mix. It has been observed that the volume expansion of cement in the pin cavity insulator can produce high enough stresses to cause radial cracks in the porcelain [14]. The probable reasons for volume expansion of cement grouts has been attributed to excess sulfates in cement reacting to form expansive phases such as ettringite and hydration of magnesium oxide to form magnesium hydroxide [15].…”