Working in the electrcal field I have seen the effects of corona discharge many times It is absolutely amazing how high voltage can break down materials and travel across insulators etc when dirt and grease etc builds up on them.
I maintain a 5000 watt AM radio station and have seen what damage 20,000 volts does in a transmitter when equiptment fails
I have seen utility company engineers use a new system i beilive is called Infrasound/ultrasound? that they can visualy Check to see if coronas are building up on transmission lines which can greatly reduce down time but needless to say this test equiptment is very expensive.
They are now looking at all cable splicers who work on medium and high voltage
cabling to become certifed possibly nationally as a way of reducing accidents and injurys from corona effect when wiring splicing on medium and high voltage cabling is not properly done.