Because of the aforementioned appeal of the regression trees technique, it
will be used to investigate the behavior of EPDM composite insulators against
the SiR contents based on the recorded experimental work. The percentage SiR
contents in EPDM composites are 0, 25, 75 and 100% respectively. Generally, the
EPDM composite polymer insulator properties are enhanced with increasing the
SiR contents percentage as shown in Figs 17 to 19.
Fig. 19 shows the effect of water droplet number upon the EPDM behavior with fixed
water droplets volume and conductivity.
Increasing the number of droplets decreases the flashover voltage at the
same droplet size and water conductivity. For instance, at 1, 3, 5 droplets, the flashover voltages are 19, 17, 16kV
and 11, 9.99, 8kV for 100% and 50% SiR contents with constant water conductivity
and droplets volume.
Fig. 20 shows the effect of water size upon the flashover voltage. The droplets
volumes are 0.01, 0.1, and 0.15ml respectively. The larger the droplets volume
is, the lower the flashover voltage is obtained. For constant water conductivity,
it is noted that the impact of the droplet volume appears clearly and strongly
for one droplet. However, the increase of droplets volume from 0.1 to 0.15ml
has less impact on the flashover voltage at 3 and 5 droplets. For instance, at
100% SiR, the flashover voltages record 19, 17, 15kV respectively for one
droplet at volumes of 0.05, 0.1, 0.15ml respectively. The corresponding data
for 3 and 5 droplets are 17, 14, 13kV and 16, 11, 10kV respectively with 1kV
Fig. 21 illustrates the relationship between the flashover voltages and SiR
contents in EPDM at various water conductivities with three droplets. The
tested water conductivities are 50, 500, and 1000?S/cm. For 100% SiR contents, 0.1ml
water droplet volume, and 3 droplets, the flashover voltages record 14, 12,
10kV at 50, 500, and 1000?S/cm. For constant droplets number and volume, it can be noticed that as the droplet water
conductivity increases, the EPDM flashover voltage decreases.
It can be concluded from
the prediction values in Figs. 19 to 21 that the hydrophobic surfaces of
EPDM composites polymer insulators were pronounced impact on the values of
flashover voltages. The electrical properties of EPDM composite insulators were
improved with increasing the silicon rubber contents. At wet conditions weather with high salinity
(i.e. low conductivity), the hydrophobic surface of EPDM composite insulator
withstands more flashover voltages.