1. P 505
Statistical Determination of Insulator Performance at Koeberg Insulator Pollution Test Station
Presented by Dr WL Vosloo (Eskom)
Dr I Gutman (STRI)
Dr JP Holtzhausen (University of Stellenbosch)

2. Typical Performance Data at KIPTS
Note: E-1 and F are the reference insulators at KIPTS and was not chosen as the optimum solution for this area.
Electrical Performance with Natural Pollution
Natural Ageing Performance

3. Statistical Approach
Pollution stress at site: probability density function f(g)
Probability for flashover at maximum operating voltage: cumulative distribution function P(g)
Multiplication of f(g) and P(g) – the area under this curve defines the risk for flashover

4. Pollution stress at site: probability density function f(g)
Measured on Insulator at KIPTS I U

5. NCI totally Hydrophilic
Probability for flashover at maximum operating voltage: cumulative distribution function P(g)
NCI totally Hydrophilic
Measured on Insulator at KIPTS

6. Calculated Number of Flashovers per Insulator per year

7. Determine What Insulation to Use

8. Predict In Service Insulation Performance
Transmission Line
Calculated
faults per year
Actual A
0,6
1,0 B
0,5 C
0,2

9. Future Work
Further investigate the use of leakage current data measured on all insulators tested at KIPTS so as to determine there statistical performance curves
Determine statistical performance curves for various standard insulators in the laboratory (ac and dc)
Establish a methodology where both sets of data can be used so as to help Eskom select insulators for the power network

10. Thank You