Indeed, one of the main goals of the analysis is to determine if there are separate power system issues to resolve that are not directly related to arresters. If system wide and therefore a failure scenario, a different mitigation strategy would likely be needed versus a situation where it was only an isolated event. In most cases, the underlying reason for conducting this type of analysis is that several arresters of similar design experience terminal overloads and the affected utility needs to find out if the problem is system wide.

Forensic analysis is the only means to properly determine which of these scenarios applies. However, if an arrester experiences a terminal overload within days of energization and with no related surges, then it is likely an indication of some form of failure. In fact, this scenario should really be called a success. While such a situation could be regarded as failure to perform its function, this is not necessarily the case.įor example, should a long-serving arrester that protects a high value asset be terminally overloaded during an overvoltage event, this can hardly be termed failure. The arrester may or may not even be in one piece at that point and electrically represents an open or short circuit.

Terminal overload applies to any event where an arresteris stressed beyond its design capability. This edited past contribution to INMR by Surge Arrester expert, Jonathan Woodworth, offered guidance on how to search for and identify the root cause behind an arrester’s overload. Here is where forensic analysis can play a role. This will allow maintenance staff to determine whether the end-of-life event was simply the arrester performing its protective function or if other issues need to be resolved that might be system wide. When this occurs, it is useful to establish the reason why the arrester or companion arresters became inoperative. *This article has been republished with the kind permission of Jon Hindle AMInstLM – Senior High Voltage M&E Installation Engineer at Grovenor Power Services*Īrresters are devices to divert lightning and switching surges and at times become overloaded to the point of failure.

Investigating Causes of Surge Arrester Failures

Surge 2 has it cracked