Test temperature is a important condition for ball pressure test, it would affect the size of the indentation. A heating oven will be used, the heating oven and specimen support shall be maintained at the test temperature for 24h or until thermal equilibrium is reached. Then the Ball-pressure Test Apparatus should be put in the specimen for 60mins, remove the pressure ball from test specimen and within 10s immerse the test specimen in water maintained at 20℃ for 6mins, then remove the specimen from water and eliminate all traces of water. Within 3mins of removal from the water measure the dimension.
According to IEC60695-10-2, the Ball-pressure Test Apparatus has strictly size as below:
The Ball-pressure Test Apparatus is consisted by pressure ball and load. The diameter of pressure ball is 5mm (r=2.5mm), and the load weight is equivalent to 20N±0.2N.
The spherical portion of indentation left by the pressure ball (dimension d) shall excludes any material deformation. If the dimension d does not exceed 2mm, it expressed as a pass. If pass the test, it shows the material will not deform under the abnormal heating condition, and no bad effect to the hazard voltage on the material, to ensure the safety of the users.
Eason Wang