In order to evaluate adhesion between ice and conductor under field conditions, a specialized tool was developed by STRI. This tool proved effective and was even later offered to CIGRE WG B2.44 to assist standardization of future field measurements. Indeed, it is felt important to standardize measurement of the impact of different remedial measures on ice coverage and to do this under outdoor conditions.
A 1.4 kg weight was used, sliding on a rod, and this rod was placed on the conductor so that it rested under its own weight. This weight was then lowered onto the conductor, first from the first half of the rod’ s length( 15 cm) and then from its full length of 30 cm – respectively referred to as‘ half punch’ and‘ full punch’.
Ice testing in the laboratory using a representation of glazed ice( i. e. transparent ice of high density) did not reveal any significant improvement in ice accretion performance as a result of the super-hydrophobic nano-coating. Similar amounts of ice, by weight, were accreted on all six conductors. However, the appearance of this ice on the two hydrophobic conductors( i. e. the RTV and the nano-coated) differed from the smooth ice found on other specimens. This difference was most pronounced on the superhydrophobic coating that continued to feature a‘ bumpy’ surface, even after 3 h of ice accretion. The reason for this could be strong polar properties of molecules at the surface of the coating that result in orientation of the water molecules, thereby affecting formation of ice, even at some distance.
Utilization of hydrophobic nanoparticles would allow for very fast recovery of hydrophobicity but probably not allow penetration of hydrophobicity through pollution layers( as is usually the case with low molecular weight components in silicone rubber). One of the most important findings from this test was that the isolated frozen drops on the super-hydrophobic coating could easily be removed just by touching, i. e. ice adhesion was very low at this early stage. On hydrophilic conductors, by contrast, ice builds
Tool developed by STRI for field comparison of ice adhesion.
Facilitated ice shedding from wind would prove beneficial to reducing accretions on conductors.( Photo INMR)
Photos: INMR © Photo courtesy of STRI
141