Which types of electrical partial discharge can be distinguished using the SONASCREEN 2 and PDReport?

Electrical partial discharges can generate different acoustic and phase-related patterns depending on their cause and location.

The SONASCREEN 2 locates the resulting sound signals and displays them as a PRPD diagram in Partial Discharge mode. Saved measurements can then be evaluated further using PDReport.

PDReport supports automatic differentiation between:

• corona discharge
• surface partial discharge

Corona discharge

Corona discharges typically occur in highly non-uniform electric fields, for example at sharp points, edges, or other areas with high local electric field strength.

These discharges can generate characteristic phase-related patterns that can be displayed in the PRPD diagram.

Surface partial discharge

Surface partial discharges occur along the surface of an insulating material. They may be promoted by factors such as contamination, moisture, ageing, or high electric field strength.

These discharges can also generate characteristic PRPD patterns.

Evaluating the measurement

Automatic classification supports the user when evaluating a measurement. However, it does not replace the technical assessment of the electrical equipment.

The evaluation should also consider:

• the location of the sound source,
• the PRPD diagram,
• the intensity and temporal behavior of the signal,
• the design and operating condition of the electrical system,
• possible sources of interference.

Where necessary, acoustic ultrasonic inspection should be supplemented by additional electrical testing methods.