ECN Forum Forums General Topics of the Trade General Discussion Area CT's

For what its worth, I am certain that lethal voltages _can_ occur on CT open secondary. In particular, with the secondary open and reasonable primary current flow, I'd bet the core saturates, causing considerable harmonic content in the secondary voltage. I would not be surprised to see extremely high peak voltages with moderate RMS voltages.

I tried to estimate the secondary voltage given a 1 square inch core and 2 Tesla saturation and 80 turns; depending on the saturation, I could see the peak output voltage anywhere from 60V on up. It would be entirely reasonable to get high enough voltage to arc over, followed by enough current to sustain the arc.

-Jon

Here
is a picture of damage from an open CT circuit. The terminal on the upper right that is not connected was jammed behind the shorting block from the factory. We energized this gear on a weekend change over. When we started feeding load I heard arcing and smelled that awful smell of something electrical burning.