MU Qiu-gu, ZHOU Kai, HUANG You-cong, et al. Study on the Repair of Water Tree Defect in XLPE Cables[J]. High voltageapparatus, 2012, 48(12): 33-37+43. DOI: 10.13296/j.1001-1609.hva.2012.12.008.
Study on the Repair of Water Tree Defect in XLPE Cables
a siloxane liquid is utilized to repair the water trees in ageing XLPE cables
and the results and mechanisms of the repair are analyzed.The short cables
whose dielectric loss factor is from 4% to 6% and insulation resistance is from 7 500 MΩ to 10 000 MΩ
are aging with 7.5 kV and 450 Hz AC until the dielectric loss factor of them grows up to around 20% and the insulation resistance decreases to 3 500
5
000 MΩ.Then the siloxane repair liquid is injected into water tree cables with a pressurized injection system.The effects of repairing experiment are analyzed through dielectric loss factor
insulation resistance and breakdown voltage.The micro
morphology of water trees in cables before and after repairing is observed with microscope observation.The repair mechanism is verified though the simulation of the distribution of electric field nearby water trees before and after repairing.The experimental results show that the siloxane liquid fully reacts with the water in water trees to form a gel polymer which is filled the water trees with.After repairing
the dielectric loss factor
the insulation resistance and the breakdown voltage is restored to those of the new cables;the electric field in cable insulating barrier becomes well-distributed;and the growth of water trees is greatly inhibit.Verified by experiments
the water trees in ageing XLPE cables can be effectively repaired by the siloxane liquid
and the insulation level of cables can be significantly improved.