I had a case where I closed in on a faulted transformer, and it spilled oil all over an expensive car located below it. This was an expensive public relations problem for our utility.
Some of our linemen close in on bayonet fuses on a pad-mount when trying to re-energize it, even though there is no fault close rating. We had a close call recently where a lineman almost got hurt doing that. The IFD would prevent this.
This is great, a safety device that makes us money.