Types of partial discharge

There are various types or classifications of partial discharge based on different criteria. The types of partial discharge can be categorized as follows:

1. Surface Discharge: Surface discharge occurs along the surface of the insulation material. It is typically visible as a tiny spark or corona discharge. Surface discharges are more likely to occur when there are irregularities, contaminants, or moisture on the surface of the insulation.

2. Internal Discharge: Internal discharge occurs within the insulation material, away from the surface. These discharges are not directly visible and can occur due to voids, air pockets, or other defects within the insulation. Internal bursts are often associated with localized breakdowns within the insulation structure.

3. Corona Discharge: Corona discharge is a specific type of partial discharge in high-voltage systems. It is characterized by the ionization of the surrounding air due to the high electric field strength. Corona discharge can result in visible glowing or hissing sounds at sharp edges, pointed electrodes, or conductors with high voltages.

4. Microdischarge: Microdischarge refers to tiny and low-energy discharges within the insulation material. These discharges are typically shallow and can be challenging to detect. Microdischarges can gradually erode the insulation and accumulate over time, leading to insulation failure.

5. Pulse Discharge: Pulse discharge refers to partial discharges that occur in short pulses of electrical energy. These pulses can have varying shapes, amplitudes, and durations. Analyzing pulse characteristics can provide insights into the condition and severity of the partial discharge.

It's important to note that these types of partial discharge are not mutually exclusive and can often coexist in electrical systems. Diagnostic techniques, such as electrical measurements, acoustic and ultrasonic detection, and high-frequency analysis, are used to identify and characterize these different types of partial discharge.