partial discharge test

datasheet as PDF-File

What is partial discharge?

• Partial discharge (PD) is a local electrical discharge, which results of defects or in homogeneours insulation material. At the terminals of the test object the current impulses of the partial discharge will be measured.
• The unit for the measurement of partial discharge is Coulomb [C] (1C corresponds to 1As). Usual measuring values of partial discharge are between 1 and 10000pC.
• In principle partial discharge of <10pC do not produce any defect in the insulation normally.
• The partial discharge test is a so called “non-destructive” test. This means if there aren’t any high PD-levels, the test-item won’t get harmed. Furthermore the partial discharge test provides a measurement of the
  test-item’s quality.

appearance of partial discharges in simple insulating arrangements

A - PD in solid insulating material (Treeing channels)
B - Corona discharges at sharp edges
C - Surfaces- or sliding discharge
D - Discharge in layer insulating material
E - Cavity discharge in gas filled cavities

There is a difference between corona discharges, which are outside of the test object and internal partial discharges, which are inside of the test objects.

fully automatic partial discharge test place to measure partial discharge down to 2,5 pC and up to 70 kV AC

At the manufacturing of electical insulation materials might appear small flaws and inhomogeneous. If thre is insulation material located between theelectrode system, which is tapped to voltage, a local overwork concerning the elctrical field might occur at these flaws. This overwork can lead to a local limited electrical discharge. Broadly spoken a partial discharge appears, whenever a discharge process brides over the distance of two electrodes. This means: a partly disruptive discharge of the insulation. Partial discharge tests are possible in little and average series.