Can You Name That Tune?

Upgrading a historic building's elevator system leads to a mysterious case of the humming conductors. - - As a power quality detective, you get to see it all from flickering lights to overheated transformers and tripped drives. But humming conductors was a first for me! I'm not talking about the low, faint hum you might hear at a transformer. In this historic building, you could hear a loud harmonic