# Research on State Diagnosis Methods of UHF Partial Discharge Sensors Based on Improved ViT
## 4 Experimental Validation and Analysis
### Datasets and Their Characteristics  
#### 4.1.1 Data Characteristics of UHF Partial Discharge Sensors in Normal Operating States  
Previous on-site actual detection work shows that different operating states of the partial discharge sensors have different data characteristics. Figure 3 shows typical plots which may be obtained when belonging to the UHF partial discharge sensors in normal operation states.  
Through the analysis of Figure 3, it can be seen that when the UHF sensors are operating in a normal state, whether operating normally or detecting discharge phenomena, each has obvious spectral characteristics. Among these, the spectrum in the absence of discharge exhibits consistently low values across all wavelengths and is uniformly distributed. When the metal tip is discharged, the discharge polarity effect of the spectrum of the collected data is very significant, and usually appears in the negative or positive half-axis of the industrial frequency phase. When the suspended metal body undergoes discharge, its anti-electric signal typically manifests within both the positive and negative half-cycles of the industrial frequency phase, exhibiting a certain degree of symmetry. The discharge amplitude is very large, the time interval between adjacent square electric signals is consistent, the number of discharges is small, and the repetition rate is low. Furthermore, when discharged by metal particles, mapping of the local discharge signal machine type effect is not obvious in terms of phase distribution; the number of discharges is low, the discharge amplitude does not display any obvious regularity, and the discharge signal time interval is not stable. When the insulated internal air gap discharges, the anti-electric signal typically appears in both the positive and negative half-cycles of the industrial frequency phase. This signal exhibits a certain degree of symmetry, with more dispersed discharge amplitudes and a lower frequency of discharge events. Based on the characteristics of the different maps mentioned above, a spectral feature library for the sensor under normal operating conditions can be constructed.  
1.2 Data Characteristics of UHF Partial Discharge Sensors in Data Failure State Due to External Signal Interference  
In this state, there is no hardware failure of the partial discharge sensor, and the failure of the collected data is primarily caused by external interference. In addition, using the UHF partial discharge sensor as an example, the following figures illustrate plots under various typical interference conditions.  
Through the analysis of Figure 4, it can be observed that, in the case of data failures caused by mobile phone interference, the noise is densely distributed and exhibits a linear increase from top to bottom. For data failures due to fluorescence interference, the data is equally dense and is particularly dense in the lower picture. For motor interference, the noise is evenly distributed across the top of the graph. For radar interference, the noise is mainly concentrated in the lower region. Based on the above features, a dataset can be created to represent the operational state when the partial discharge sensor fails to collect  
Figure 3: Data characteristics of UHF partial discharge sensors in normal operating conditions.  
data due to interference. It is worth noting that the signals received by the partial discharge sensor may be the superposition of the effective signal and the interference signal.  
Images of different sensor states have distinct features, forming the basis of the experimental dataset. The improved ViT model can extract the features of these pictures and classify the extracted features well. Thus, the improved ViT model, designed as a data-driven model, is used to diagnose the state of high-frequency partial discharge sensors. In this paper, model training was carried on an NVIDIA GeForce GTX 1660 Ti graphics card.