Impact of Hardware Design on Failure Mode of Protective Devices
a case study
by Paul Myrda and Charles Perry, Electric Power Research Institute, USA
This article describes the impact of hardware design and the resulting failure modes on the overall reliability of protection systems. A specific device failure and the subsequent response is presented. During a recent maintenance test at a utility site, the device under test failed and the resultant failure caused all of its outputs to “turn on.” Had this device not been under test and isolated from the rest of the substation protection circuitry, a significant outage involving a large number of customers would have occurred. Close collaboration by all parties involved including the manufacturer, utility and EPRI uncovered a set of unique events that led to the failure. This case study will provide a number of insights useful to the smart grid and also existing protection system designs.
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