Three-phase pollution test of diamond-shaped “suspension” insulator arrangement

for T-pylon tower

2

Background and goal• The National Grid isplanning for the new 400kV overhead line with T-pylon towers

• Dielectric (lightning andswitching overvoltages)and ice performanceperformed by STRI

• Goal of this paper:verification of pollutionperformance

• Full-scale three-phasetest to be developed

3

Challenges

• No IEC test for polymeric(composite) insulators

• No test for three-phasearrangement

• No IEC test for thesimulation of recovery ofhydrophobicity

4

Methodology-1: principles of IEC 60507 (solid layer)

5

Methodology-2: principles of CIGRE TB 555

6

Methodology-3: full-scale three-phase tests from 3 single phase transformers

7

High repeatability in pollution parameters

8

High repeatability in leakage current parameters

Practical summary

9

• Unique three phase full-scalepollution test for the complicatedgeometrical structure for 420 kVOHL equipped with compositeinsulators with hydrophobic surfacehas been successfully developed.

• Target pollution level withstood fortwo structures (no flashovers).

Scientific summary

10

• The test is applicable for complicatedgeometrical structures.

• The test is repeatable.• Reported to CIGRE within workinggroup D1.44

• Verified at different configuration.

Thank You!

11