The maintenance of a transmission line

Maintenance of a transmission line is a fundamental part of its functioning, a need that is accentuated by its outdoors location. Such maintenance work, which can add 50 years of life to a transmission line, requires highly qualified electricity technicians and mechanics with the tremendous physical and mental strength needed to gain access to the nearly impenetrable places where these structures are sometimes found.

Transmission lines carry electrical power and their characteristics make them conditional to ongoing checks and inspections. Power transmission lines are made up of towers and they run hundreds of kilometers through vastly different geographies and climates. The ATS line covering more than 880 kilometers, for example, is Peru’s longest transmission line.

” A transmission line has an average life of 30 years; however, if properly maintained, it can operate for up to half a century.

This characteristic exposes transmission lines to numerous external factors, such as corrosive agents, ice, wind and ultraviolet radiation, which damage their structures, components and parts. It is therefore essential for lines to undergo the regular maintenance that can extend their useful life by 30 (typical) to 50 years.

However, before the actual maintenance takes place, engineers must first draw up a diagnostic assessment. They have two ways to do this. The traditional method consists of setting up a schedule of periodic visits to the line. This means getting a team of two to three people, usually electrical technicians and mechanics, to the foot of the tower.

The second way to inspect a line involves the use of technology, a method that does not necessitate taking the line out of service. Technicians make use of infrared and ultraviolet light cameras and ultrasound detectors to obtain data locally or remotely. In the latter case, the information travels via cellular systems to a control center.

” Maintenance can take hours, days and even weeks. This depends fundamentally on the ease with which they can get to the towers, as well as the magnitude and complexity of the maintenance operation.

With the diagnostic assessment in hand, they can schedule a date for cleaning the line and repair it if needed. Maintenance can take hours, days and even weeks. This depends fundamentally on the ease with which they can get to the towers, as well as the magnitude and complexity of the maintenance operation. For example, in some cases there may be highways or dirt roads for gaining access to the towers. In other cases, however, technicians have to walk for hours and climb peaks of over 4,000 meters above sea level, as occurs in Peru.

Transmission line maintenance is a recurrent process and involves cleaning insulators, the elements located at the top of the tower which hold the cables that transport power (conductors). In order to rid them of dust and other particles suspended in the air that build up, operators spray them with pressurized demineralized water using a hose. To do so, they must climb the 35- to 50-meter-high tower structure beforehand or go up in a crane to place themselves in front of them. This maneuver sometimes also entails replacing broken components with new parts.

Like ocular inspection, maintenance can be carried out with the line in operation (hot-line maintenance) or inoperative (cold-line maintenance). The former option is applied extensively worldwide and constitutes a much more ambitious method than cold-line maintenance. Specialists must be extremely careful and meticulous in executing maneuvers, especially on extra-high-voltage lines, which are those that carry the most energy. There are, in fact, international standards and procedures such as the Institute of Electrical and Electronics Engineers (IEEE) which establish, for example, the safety and security distance to be adhered to by the technical expert when cleaning the insulators.

In this field, Abengoa boasts a number of successful experiences in Brasil, Chile or Peru, among others. In the case of Peru, Omega Peru, the Abengoa company tasked with transmission line operation and maintenance, carried out operations of this type for the first time in Peru on a 500 kV line in June this year.

Roberto Guerra,
Project and Maintenance Oversight Manager for Omega Peru.