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Transmission Line Corrosion

Internal corrosion is a major factor limiting the life of steel reinforced aluminium conductors. ATTAR has over 15 years of experience assessing the condition of conductors for the power transmission industry, both locally and internationally.

Our experience indicates that whilst a conductor might have experienced some general corrosion over time, more often it is the serious localised loss of the protective coatings on the internal supporting steel core, caused by local environmental conditions, that is of most concern.

ATTAR offer a Non-Destructive, Over Head Line Corrosion Detection Services for the comparative assessment of zinc loss from ACSR/GZ and aluminium cladding loss from the ASCR/AC steel core of the conductors. This system can detect corrosion often well before it is visible or detectable by infra-red methods.

Localised micro environments can result in significant corrosion leading to costly and potentially dangerous conductor failure. The conductor age is often not an indicator of conductor’s ability to continue in service.

By targeting and testing a percentage of whole spans of conductor, a picture of the transmission network condition can be formed. This allows cost-effective risk based planning to prioritise spend in any asset replacement program, allowing safer and less costly replacement based on good statistical data as a result of the identification of the more severely corroded sections.

Traditional methods of destructively sampling of short lengths of conductor within a span, has a much lower probability of characterising the line condition and identifying any corroded sections of conductor that have the potential to fail.

The Equipment

The equipment is placed on the “live” conductor by a small team of linesman and then operated remotely. The equipment can be operated on lines with voltages over 500kV – no need for costly and/or complicated line outages

Using a coil placed around the conductor, the device generates a magnetic field and induces eddy currents around the strands in the core of an ACSR conductor. A second coil picks up the ‘strength’ of these eddy currents and this data allows ATTAR to analyse a conductor’s condition. Loss of aluminium cross section is also detectable.


Reports are representative of the line and easy to read.  The condition of the conductor is colour coded in terms of remaining zinc (or aluminium cladding) and each span tested is reported with a colour-coded condition versus distance bar graph. 

Accuracy of the instrument allows individual condition assessments to be made down to centimetres, ensuring that localised lengths of corroded conductor are identified.





















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  • OHLCD overview
  • OHLCD for engineers