Superficially, the distribution of electricity supply from power plants to households looks fairly simple, with power lines hung neatly from one pole to another and another.


         But the truth is, before the power supply is dispatched safely to consumers, there are several stages of task involved to complete the process. One of them is the inspection and maintenance of high-voltage transmission lines — a work which many people may have come across but do not really know what they are doing up there.

         In the world where technology is advancing unstoppably, more and more inventions are created.

         The Electricity Generating Authority of Thailand (EGAT) is always searching for new innovations in power generation and transmission. Though certain existing tools and components are still functioning efficiently. EGAT believes that there can be tools to greatly facilitate the works and further minimize the risks involved. That gave birth to the “Four - Wheeled Sling Crawler” (FWSC), a brainchild of EGAT personnel, supporting “Thailand 4.0” Plan and heightening the security and reliability of power transmission.

         The FWSC is a self - driven foldable facility developed for inspection and maintenance of 230-kV dual transmission lines. Until now, such tasks have been performed by using three techniques — having engineers “walk” on the cables; cable pulling and using three - wheeled cable cars. The problems and constraints derived from using those techniques are used to perfect the FWSC.


         Mr. Prameth Wuthisin, the engineer attached to EGAT’s Central Region Operation and FWSC team leader, said EGAT’s transmission grid is extensive, dispatching electricity nationwide to the distribution systems of the Metropolitan Electricity Authority and Provincial Electricity Authority which in turn deliver power supply to consumers.

         “EGAT transmission lines need to be regularly inspected and undergo proper maintenance to ensure they are in the tip - top working condition,” noted the Engineer level 7.

         The FWSC comes in the form of basket that allows engineers to perform their duties either by standing or sitting position. The basket is attached with rollers hooked to conductor lines. The rollers can move back and forth by its own mechanism with braking function and traction enhancement — all facilitating the duty performance. However, to bring the facility up to the high - voltage lines which are more than 20 meters above ground is a high - risk exercise. The engineers who man FWSWs must be fully equipped with safety gears such as full - body fall protection harness, fall prevention ropes, helmet and gloves in order to minimize risks. It is fair to say that the FWSC is the most innovative facility developed to best carry out the mission so far.


         The task of looking after transmission lines does not only confine to the construction and operation stages, but continues afterward on regular basis, said Mr. Prameth.

         “It’s all about preventing malfunction and correction when problems arise. This is where the FWSC plays a crucial role,” he added.

         The FWSC itself will evolve with the metal parts being replaced by fiber materials to make the facility lighter. There are three sets of FWSC in service and their innovative features have reduced human errors associated with having line men “walk” on the cables. It proves to be cost saving, safer and convenient for fulfilling the task. The invention is not only a pride of EGAT but highly admired by the Thai industry as a whole.



         It won an EGAT invention award in 2015 and became a recipient of bronze and Taiwan patent awards from the Taipei International Invention Show & Technomart 2015 in a nomination by the National Research Council of Thailand (NRCT). The FWSC was patented in 2017.

         The task of looking after transmission lines to ensure uninterrupted power supply to the public requires expertise and dedication. EGAT is embracing research and development that will spur innovations to heighten security and reliability of electricity supply to all homes in Thailand. That is our commitment.