Many beginners find this question strange - the oil cup looks clean, why can't it be used directly? The instruction manual clearly states that "new oil cups or newly cleaned oil cups should be punctured 24 times before testing", and there are sufficient technical reasons behind it, not arbitrary regulations from the manufacturer.

The surface condition of the oil cup affects the test results

Although the surface of the new oil cup electrode appears smooth to the naked eye, there are processing marks, surface stress concentration points, and minimal residual pollutants on a microscopic level. These micro defects will generate local electric field enhancement effects between the electrodes, causing the oil film to break down at a voltage far below the true dielectric strength during the first breakdown, resulting in significantly lower results.

The "break in" effect of 24 breakdowns

Multiple breakdowns have two effects: one is that the trace carbon particles generated by each breakdown will fill the small unevenness on the electrode surface, gradually making the electrode surface tend towards a "standardized" state; Secondly, a small amount of carbon particles are uniformly dispersed in the oil to form a stable initial state, which improves the reproducibility of subsequent test results.

Simple analogy: Just as a new machine requires a break in period, a new oil cup also needs to establish a stable testing state between the electrode surface and the oil sample through multiple punctures. After 24 rounds of breakdown and running in, the test results of the oil cup meet the reproducibility requirements of the national standard.

The same applies to newly cleaned oil cups

The thoroughly cleaned oil cup has removed the residual carbon particles on the electrode surface, and the surface condition has returned to a "new" state. Therefore, it also needs to undergo 24 cycles of breakdown pretreatment. If the test is conducted directly after cleaning, the results will also be lower, which will affect the judgment.

Practical operational suggestions

It is best to use the same type of insulating oil as the formal test (not necessarily the tested oil sample) for the oil sample used for 24 pre breakdown tests. The data from these 24 trials will not be included in the formal experimental report and will only be used for preprocessing.

HZJQ-X1 supports up to 10 cycles per setting, and 24 preprocessing cycles require 2-3 rounds of operation. After each round is completed, the oil sample is re injected to continue. Although slightly cumbersome, this is a necessary step to ensure the reliability of test data, especially in situations where a formal testing report is required and cannot be omitted.