Breakdown voltage

OELCHECK test instrument: Insulating oil test device DPA 75
Sample quantity: 600 ml
Unit: kV
Test result: electric breakdown voltage of insulating fluids and oils for electric drives
Result range: 0 - 75 kV
Analysis for: transformer, switch and insulating oils, oils for electric drives
Brief description:

The fluid to be analysed is filled up to the top of a testing vessel without bubbles. There are two spherical caps made of brass 40 mm beneath the surface of the liquid. The distance between these electrodes is set to 2.5 mm using a distance gauge.

Once the testing vessel is sealed, the sample is homogenised for 5 minutes first of all. A sinusoidal AC voltage is then placed on the electrodes and increased at a rate of 2 kV/s, until the first spark discharge occurs between the electrodes. The voltage reached up until this discharge is the result of the investigation. The experiment is performed with the same vessel contents six times. Each time, the sample is homogenised for 2 minutes between the individual measurements.

The mean of the individual measurements is given as the result.


Insulating fluids are required to insulate high potential differences, soak fibrous insulating materials or contribute to arc quenching, as well as ensuring heat extraction. A key test criterion is therefore the electric breakdown strength, i.e. the voltage below which no spark discharge occurs under precisely defined conditions.

Underlying test standard: DIN EN 60156
comparable test method:  
Deviating methods:

ASTM D 3300: impulse conditions

ASTM D1816