What is the main characteristic of floating metal discharge?

The main characteristic of floating metal discharge is that it emits an ultrasonic sound that can be detected. This phenomenon typically occurs in high-voltage systems where metal components may not be properly grounded. As the electrical energy finds a path to ground through the air or other insulating materials, it can create vibrations that produce ultrasonic frequencies. These sounds can often be captured using specialized equipment, making them useful for identifying issues within electrical systems.

The detection of ultrasonic sounds related to discharge can serve as an early warning system for potential electrical faults, allowing for maintenance or repair before more serious issues arise. It highlights the importance of monitoring high-voltage systems to ensure safe and reliable operation.

The other options do not present the primary characteristic of floating metal discharge. They may pertain to other issues in high-voltage systems but do not correctly define this specific phenomenon.