IEC 60156 Insulating Liquids - Determination of Breakdown Voltage
IEC 60156 Insulating Liquids - Determination of the Breakdown Voltage at Power Frequency - Test Method
10 Report
Report the mean value, in kilovolts, of the six breakdowns as the test result.
The report shall also include: the sample identification, the value of each individual breakdown, the type of electrodes used, the frequency of the test voltage, the temperature of the liquid, the use of a stirrer (if any).
11 Test data dispersion
The scatter of individual breakdown voltages has been found to be very dependent on the value of the result. The graphical representation of Figure 3 indicates the values of standard deviation/mean ratio which have been found in a large body of test data in several laboratories using transformer oil.
The full line in the graph shows the distribution of the median value of SD/mean as a function of the value of the mean. The dotted lines indicate the expected 95 % range of values of SD/mean as a function of the value of the mean.
