Evaluation of Field Returned Insulators by Ron Duckstein

The age of the transmission grid in the United States and elsewhere has required increased focus on the condition of old insulators still in service. Indeed, many utilities have already started testing some of their oldest lines to forecast and plan for refurbishment and capex expenditure. Evaluating the condition of such assets can be done using different methodologies. For example, CIGRE TB 306 offers a statistical approach based mostly on mechanical performance of insulators removed from service. Additionally, flashover, M&E, thermo-mechanical and steep front wave evaluations also provide valuable information. Today, an increasing number of utilities are looking at laboratories offering the full scope of ANSI, IEC or CSA test programs for such investigations. Quantities of units tested clearly help in establishing a statistical diagnostic of the condition of insulators but utilities are often not able to dismantle large sections of lines for such work. Therefore, the most pertinent test program should be designed using customized approach to best fit the environment or the type and age of test samples as well as their application. This presentation offers an example of what can be offered in this regard based on a new U.S. factory for glass insulators established in 2017. This facility offers a laboratory capable of performing all tests required by international standards and test campaigns have already been conducted for North American utilities from the east to the west coast.