Substation Maintenance Electrician. Recently went on a call-out for a 13.8kV Teritary ground fault. Fuses to the grounding xfmr were not blown but one phase had a high resistance across the fuse, ~100 ohms. Other to phases were 2 ohms. The fuse was changed and the ground went away. But when re-energized, the Tertiary Ground relay target in control house blipped a few times intermittently, but alarm never came in. A hot insulator upstream on the same phase as high resistance fuse was found when we IR scanned, insulator was cracked, and it was replaced. We re-energized again and no blip at the target, no alarms. My question is what happened? Why didn't the fuse blow if there was a fault in the Grounding Xfmr? Is it possible the high resistance fuse was a symptom of the damaged insulator?
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High Resistance Grounding Xfmr Fuse
- Thread starter CTWELSH82
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