Practical Field Inspection & Condition Assessment of Transmission Insulators
by Dennis Schlender

Most utilities and large industrials with transmission networks have varying degrees of Condition Assessment Programs. Reviewing the condition of insulation constitutes an important part of such inspections since it is key to the reliable operation of the system. There are a range of options available to complete a detailed review of insulation performance, including removing samples from a line and testing them in a laboratory, infrared thermal imaging, daylight corona inspection and visual inspection. Since budget limitations invariably influence the extent of testing that will take place, coordinating and consolidating what goes into a condition assessment program can help reduce costs and ensure more effective use of capital. During any inspection and life assessment of insulation, it is important to understand what to watch for, how and where to look for signs of damage and why any damage may be starting. This presentation provides a practical approach to visual field inspection and related condition assessment, as needed for various insulation components. Such an approach can help minimize the financial and management burdens related to completing condition assessments in a timely and efficient manner. While this approach does not eliminate possible need for more rigorous additional testing and inspection, it can be used to help prioritize its implementation.