Partial discharge caused by internal defects of epoxy resin is often the main cause of insulation failures of epoxy-potting equipment such as pulse power supply. Effective insulation test of epoxy resin is the key to ensure the safe operation of equipment. In order to study the excitation characteristics of multiple-frequency square wave voltage on partial discharge of epoxy pot-sealed micro-defects

epoxy resin bubbles and delamination defects are prepared in this paper

and the effects of different power supply frequencies and rising edge of square wave on defect PDIV

average discharge amplitude and discharge frequency are studied. The results show that PDIV of epoxy resin micro-defects is positively correlated with power supply frequency and square wave rise time. The average discharge amplitude is positively correlated with the power supply frequency

and negatively correlated with the square wave rising time. The discharge frequency is negatively correlated with the power supply frequency and the rising time of square wave. The discharge of bubble defects is relatively sensitive to the changes in power supply frequency and the rise time of square waves

while delamination defects are relatively less affected by both. The analysis shows that

for bubble defects with a diameter ranging from 200 μm to 1 mm and delamination defects with a delamination depth of 5 to 20 μm

a unipolar square wave pulse with a power supply frequency of 50 Hz and a rise time of 1 μs can prompt the defects to produce obvious discharge phenomena at a relatively low voltage level

thereby enabling the insulation to be tested under a relatively high insulation margin. The research of this paper is of great significance to the insulation assessment and application of epoxy potting equipment.