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"Our deepest fear is not that we are inadequate. Our deepest fear is that we are powerful beyond measure…”Nelson Mandela. South African Statesman , 1993 Nobel Prize for Peace, b.1918

Implementation of 220 kVIn-Service Insulator Performance

Test Tower in Namibia

Authors:

Dr WL VoslooF Engelbrecht

N HegerDr JP Holtzhausen

Beulah Sepo LimboNampower: Assistant EngineerMasters: Electrical Engineering

University of Stellenbosch

Introduction

Walmund 220 kV Test Tower

Swakopmund

Walvis Bay

Walmund Insulator Performance Test Tower

Design of the Test Insulators for Phase A,B,&C

A1: Manufacturer A, SR, 20mm/kV,S/P=1.6, no corona ring.A2:Manufacturer B, EPDM, 25mm/kV,S/P=0.9, with corona ring.A3:Manufacturer A, SR, 25mm/kV,S/P=1.1,no corona ring.B1:Manufacturer C,SR,25mm/kV,S/P=1.3,no corona ring.B2:Manufacturer C,SR,25mm/kV,S/P=1.3,with corona ring.B3: Manufacturer C,SR,25mm/kV,S/P=1.3,with corona ring.C1:Manufacturer B,SR,25mm/kV,S/P=0.9,with corona ring.C2:Manufacturer B,SR,25mm/kV,S/P=0.9,with corona ring.C3:Reference,Glass,fog type, cap and pin,25mm/kV,form factor=10.3,no corona ring.

Walmund Substation with the Insulator Test Tower

Walmund Insulator Test Tower

Insulator Test Tower for One Phase

Walmund Insulator Test Tower

Commissioned on the 31st March 2006.Recommissioned on the 9th June 2006.

Objectives of the Walmund Insulator Test Tower

1. Compare A1 with A3 to determine the effect that different Specific Creepage Distance and S/P ratio has on the Insulator.

2. Compare A2(EPDM) with C2(SR) to find out the effect that different materials have on the performance of the Insulators.

3. Compare A3 with B1 and B3 with C1 to find out how SR Insulators from different manufacturers behave.

4. Compare B2 with B3 and C1 with C2 to determine the effect that horizontal and vertical orientation has on the Insulators.

5. Compare B1 with B3 to see the effect that corona rings have on the performance of the Insulator.

6. C3 is a referenced horizontal, glass cap and pin disk string.

Walmund Substation

Experienced Pollution FlashoversInsulators were greased with siliconeInsulators were coated with RTV SR.CT’s have Scd = 18 mm/kV.For diameters above 500mm, the effective Scd is given as 14.4 mm/kv.

Walmund Substation

Walmund Substation

Walmund Substation

Pollution Monitoring

Directional Dust Deposit Gauges (DDDG)

Insulator Surface Conductivity Monitor (ISCoM)

Climate Monitoring

Accumulated RainfallRelative HumidityTemperatureWind Speed and DirectionUVB Solar Radiation

Data captured at Walmund Insulator Test Tower

Pollution Data Climate DataLeakage Current Data

Pollution Data

ISCoM Surface Conductivity

Max = 1.9 SAvg = 1.5 Sµ

µ

Climate Data

Average Relative Humidity vs Time of Day plot

The Average Maximum Absolute Leakage I peak

Maximum Leakage Current on the Glass Disk(C3)

Maximum Leakage Current for EPDM (A2)

Maximum Absolute Leakage Current Peak for A2 &C2

Accumulative Resulting Charge on Insulators A2 & C2

Accumulative Resulting Charge for Insulators B2 & B3

Conclusions

A 220 kV Insulator Performance Test Tower has being implemented.The First series of data shows promising results.The effect of Material Choice and Insulator Orientation is well demonstrated.The data obtained correlates with the Results obtained from Clansdale Insulator Performance Test Tower in Natal.

Recommendations

Data should continuously be captured for at least 10 years so that the effect of Material Ageing can be investigated.The data should be entered into the the Insulator Selection Tool Program every 2 years.This is to aid Namibia with Insulator Selection for the Power Network.

Thank You!!!!!!!!