Methods for Detecting Partial Discharges

Partial discharge refers to the phenomenon where, in electrical equipment, the electric field strength generated by an applied voltage is sufficient to cause discharge in localized insulation areas—but without the formation of a stable discharge channel within those areas. This type of discharge is primarily observed in high-voltage equipment.

1. Horizontal Comparison (Analogy Among Similar Items)

So-called horizontal comparison involves comparing test results of similar devices. When the individual test result of a particular device of the same type is significantly higher than those of other同类 devices, it suggests that this device may have a potential defect. Table 1 shows the test results for a group of 10kV cables. As evident from Table 1, the test result for Cable Head 6 is markedly greater than those of the other同类 cable heads. Based on these measurement findings, it can be concluded that discharge phenomena have been detected at Cable Head 6, necessitating the implementation of appropriate corrective measures.

Methods for Partial Discharge Detection
 

Method Two for Identification

2. Longitudinal Comparison (Trend Analysis)

So-called longitudinal comparison involves analyzing test results from the same equipment at different points in time, followed by a comparative analysis to assess the equipment's operational condition. Table 2 shows the test results for the compartment corresponding to a specific 10kV current transformer over various periods. From these test results, we can see that the discharge intensity of this current transformer has been gradually increasing—and by the tenth month, it has already reached 50 dB. Therefore, appropriate measures should be taken promptly to address this issue.

Methods for Partial Discharge Detection