How Cables Fail-the Myths and Fundamentals to Ensuring Long Cable Life

Abstract

“How do cables fail?” is a loaded question. The mechanisms by which many cables fail are presumed unknown due to the catastrophic failure site being un-diagnosable post failure. There are many myths regarding the phenomena of what causes a cable to fail. The expected life of cables is also a hotly debated topic. “Cables last 40 years” is the common mantra most asset managers live by. There are many other myths as well such as “Water trees fail cables” and “Electrical trees have very short lives”. These myths will be discussed and debunked. An understanding of what really causes cables to fail will be described allowing the asset manager to make corrective actions prior to having an unplanned failure. Key cable issue fundamentals will be presented that need to be understood to help promote a long cable life. Proper cable system partial discharge (PD) assessment is very important in helping to ensure long cable life. Statistically significant supporting data will be presented. Assess first, then act on the findings to guarantee a long cable life.