EXPERIENCE WITH THE MERRY-GO-ROUND TEST

Studies of the Merry-go-round test (MGR), using a newly-built apparatus, and their influence on the performance of different HV polymeric outdoor insulation housing materials are presented. In the test, the surface leakage currents, mass and wettability changes of the studied samples were monitored. The investigated materials were bisphenolic and cycloaliphatic epoxies, HTV and RTV silicone rubbers, and EPDM rubbers. Results show that the epoxies containing a silane-treated filler perform very well in the test. On the other hand, the silicone rubber performance, except for preservation of its hydrophobic properties, was comparable to the EPDM ones. This is contradictory to the material's field performance and indicates that there are still problems with interpretation of the MGR test results as well as their correlation to natural service experience. © 1990 IEEE