Ethylene-propylene rubber cable terminals for EMUs need to be manually stripped except for the semi-conductive layer during installation

which is likely to cause circular cutting defects and lead to discharge. At the same time

the defects are easily filled with gas to form air gaps

which will accelerate the development of discharge and eventually cause severe cable impact wear failure. Firstly

a finite element analysis was performed on a cable terminal containing a ring-cut defect within 60 mm from the truncation

and the maximum field strength was calculated at the ring-cut. Then

a discharge test was performed at a power frequency of 25 kV

and the characteristics of the PRPD and PSA spectra were analyzed. The gray value of PSA spectrum was used for K-means clustering feature extraction. The results show that the location of the cireular cut defect is closely related to its influence on the insulation performance of the EPR cable

and the circular cut defect within 60 mm from the cut-off point can not be ignored. When the continuous discharge pulse voltage difference meets the same absolute value

the defect is close to the truncation and the impact is extremely serious

and the effect is smaller when the distance exceeds 60 mm. Combined with the discharge characteristics

it can be seen that the parameters

such as the frequency of the PSA spectrum with a gray value of less than 255 in the maximum proportion in zone 5

the minimum proportion in zone 4

and the classification centering feature

can provide important information for judging the location of the circumcision defect and the insulation status of the EPR cable theoretical basis and data reference.