Got lucky yesterday troubleshooting a VFD error code.

The dust collector - a 3hp 3-phase Torit cyclone powered by a Teco FM50-203 VFD - has been in place as-is for about three years. It was running and mysteriously "shut down" while I was setting up a jig for a cut. Got out the ladder to feel the temp on the motor (warm only) and look at the VFD monitor for clues. The panel showed LV (low input voltage) and the manual provided the logic for troubleshooting. What I was shocked to find was that one of the legs outside the disconnect was passing just 100 out of an expected 120 volts. So what I thought was going to be a major service disruption turned out to be a quick trip to the corner hardware store for a replacement fuse.

There was really no reason for the fuse since the circuit is protected by a breaker located on the other side of the shop. I'm sure it was simply a case of grabbing an appropriately sized available disconnect to make it easier to turn off power for the VFD, and that the disconnect happened to have fuses. The fuses at 15 amps were a bit low for the 30a/10ga single-phase circuit.

Just a heads up to others with voltage sensitive equipment. I had never experienced this with a fuse but it turned out to be an easy to analyze and fix issue.