Frequency of transmission line outages in Canada

Frequent transient and sustained forced outages of transmission equipment can significantly affect the performance of industrial and commercial power systems and the processes they control. A knowledge of the primary causes (e.g., adverse weather, defective equipment, etc.) of transmission line sustained and transient forced outages and which physical components of a transmission line (e.g., line conductors, structure, hardware, etc.) are affected is essential for designing and maintaining reliable transmission systems. Historical transmission reliability data provides the ability to predict the performance of various transmission line configurations and assess the impact of forced outages on industrial and commercial power systems. When no historical voltage sag data is available, historical transmission line reliability statistics can be used to predict the voltage sag activities at a particular site. This paper presents a summary of the Canadian Electrical Association´s Equipment Reliability Information System statistics on the forced outage performance characteristics of transmission equipment for Canadian utilities for the period 1988-1992. The paper reveals the structure of the database and relevant summary data necessary for the application of these reliability methodologies