Elbow surge arrester mode of failure tests

The author describes the mode of failure of elbow surge arresters and proposes a method to limit the outcome of violent failures. Elbow arresters were tested in a prefailed condition at various fault current magnitudes and durations to determine their failure mode. Based on the test results, it was determined that all elbow arresters should be held in place by means of a bail wire or similar device. To reduce the probability of injury to a lineman, the elbow arrester has to stay on its bushing and the valve blocks either have to be contained in the housing or expelled to ground by the release of the ground cap. It is concluded that improvement in the arrester and bail wire design is warranted. The use of ground disconnectors should also be considered and evaluated by the manufacturers