The most flexible and widely used form of energy, which is considered a fundamental input for economic and social development, is electricity. In the electricity sector, efficiency and continuity of energy supply are essential, especially in a world that is increasingly dependent on electricity and whose demand is only growing. As a result, it is becoming increasingly expensive and unfeasible for electricity utilities to shut down their assets for maintenance. As a result, the most efficient strategy for meeting maintenance demands on distribution networks and transmission lines is the Live Line Working.
In this article, we’ll explore what Live Line is and its three main working methods, showing their importance for efficient and safe operation in the electricity sector.
What is Live Line?
The Live Line concept refers to the methodology used to carry out maintenance on electrical systems without disconnecting the circuit. This is crucial both to avoid inconvenience to consumers and to optimize the productivity of energy distribution and transmission companies.
This work has different names in different parts of the world:
- Trabajos con Tensión(TcT);
- Línea Viva (LLVV);
- Live Working;
- Hot Line;
- Live Line Working;
We can understand any of the terms mentioned above as Live Line. This method is highly secure and follows 3 additional basic premises demonstrated in the following triad:
In other words, each of these pillars is indispensable and interdependent. The methodology only works when they are all present and operating together. Specialized companies, such as CTST, offer training aimed at enabling and retraining professionals to work safely and efficiently with these techniques.
The 3 methods of Live Line Working
In the electricity sector, Live Line can be carried out in three different ways. Each of these methods is chosen according to the type of maintenance required, the voltage level of the circuit, the complexity of access to the system, and other various factors. Let’s take a closer look at each of the three methods:
Hot Stick method
Working with Hot Stick method procedures, the electrician generally remains at ground potential. This method is mainly characterized by the need to keep the lineman at a safe distance from the energized conductor. To do this, trained professionals use hot sticks to carry out various tasks on lines and networks without the need for direct contact with the energized system. These tools are highly versatile, mechanically and electrically resistant. They come in various types and sizes, adapted to specific tasks, such as measuring voltage, carrying out maneuvers, temporarily replacing certain components, among other procedures.
With regard to positioning and lifting equipment, the revised ND 4-4, made available by CEMIG Distribuição, states that in the hot stick method “electricians perform maintenance on energized networks while at ground potential, positioned on structures by means of ladders, spurs, fiber steps or even at intermediate potential (…)”.
In this context, the combination of the right tools and the correct use of positioning equipment makes this method a versatile and safe solution.
Hot Sticks method is widely used in distribution networks and transmission lines at any voltage level, especially where positioning is limited.
Barehand Method
When working at potential, the electrician comes into physical contact with the energized circuit, operating at the same electrical potential as the conductor: the phase potential. In this method, the professional remains at the same electrical potential as the circuit throughout the maintenance of the system.
The use of conductive clothing characterizes the method, which works on the same principle as the Faraday cage, isolating the operator’s body from the effects of the electric field generated by the conductor at high voltages. These effects can cause unprotected electricians to feel tingling sensations, burns and other discomforts.
At higher voltages, the Hot Sticks method, although more limited, is also applied during the potential equalization process before the lineman comes into contact with the circuit.
Working on the potential requires a high level of specialization, training and rigorous procedures, as well as rope climbing techniques and safety equipment to access the structure.
This method is generally used in High and Extra High Voltage Transmission Lines and Substations, from 35kV upwards.
Contact Method or Rubber Gloves Method (Intermediate Potential)
In this mode, the lineman does not work at phase potential or ground potential. They use equipment and tools that isolate them from the energized potential and the ground potential, thus working at a so-called intermediate or floating potential.
The trained professional uses not only insulating gloves and sleeves that are highly resistant to electricity, but also insulating equipment, such as protective covers and blankets, which allow direct handling of the energized conductor. This equipment controls the risk of accidental touches, protecting the electrician and the system from short-circuits, electric arcs, electric shocks and, consequently, power cuts.
In addition, the use of lifting and positioning equipment, such as aerial baskets, scaffolding, platforms and insulated ladders, ensures that there is sufficient resistance for the worker to be protected in conditions of isolation from the circuit.
This method is widely used in Distribution Networks and Medium Voltage Substations, between 1 kV and 35 kV. This voltage level limitation in this method is due to current material and equipment technologies. At high voltages, gloves, sleeves, covers and blankets would be thicker and heavier to the point of making it impossible for electricians to work.
Finally, suitable lifting equipment facilitates operator access, allowing detailed tasks to be carried out safely on the power grid, allowing the power supply to continue.
Conclusion
In many Live Line maintenance situations, it is quite common for professionals to use more than one method during the same operation. It is also possible to use equipment from one method in another to carry out certain tasks. In short, there are several ways of carrying out the same procedure. The choice of method and equipment depends on a good risk analysis, the availability of resources, the knowledge and strategy of the team involved. Each maintenance situation requires careful analysis to determine the safest and most effective approach.
In addition, teamwork is fundamental in this process, as communication and coordination between team members are essential to ensure that methods and equipment are used properly, guaranteeing the safety and success of the operation.
In order to keep workers up to date with the best practices of the Live Line methodology, investing in specialized training and periodic recertifications is essential. If your company is looking to train its maintenance professionals or would like to know more about our training, get in touch and find out how we can help optimize your operations safely and efficiently. Together, we can guarantee a safe and reliable future for the electricity sector.
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