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Forcibly ventilating encapsulated dry transformers is key to managing the heat generated by energy losses.
Heat generates the temperature increase in two of its main components: firstly, in the magnetic circuit, made up of the core, which is the one that generates the no-load losses of the equipment, which are constantly present while the equipment is energized and are independent of its load; secondly, in the active parts, made up of the windings (primary and secondary), which generate short-circuit losses, which increase quadratically with the current delivered. The sum of the two is the total losses.
Encapsulated dry transformers allow the installation of forced ventilation as a way of having a power reserve, which can be used temporarily according to the demand of the equipment, preventing the transformer from suffering temperatures higher than the thermal class to which it belongs.
The use of axial air forcers, installed at the bottom of the coils, generate an upward flow of air inside the coil ventilation channels, allowing an overload of up to 40%, given the great efficiency of the system.
Forced ventilation should not be used permanently, and this availability of extra power should not be considered as the nominal power of the equipment, since the average useful life of a fan is around 4 years, while that of a transformer is around 30 years, conditioning the reliability of the transformer’s supply.
Why is ventilation necessary in encapsulated dry transformers?
Three situations could be defined where the use of forced ventilation is indicated in this type of transformer:
1. Temporary overloads due to consumption peaks. It is normal for transformers to have higher energy demands than nominal ones, for short periods of time, without justifying the use of equipment with higher powers. In these cases, the ventilation systems maintain the temperature of the equipment within the limits of the standard, without generating premature aging of the insulation of the equipment and, therefore, shorter useful life.
2. Inadequate rooms. The rooms that house the transformers must be able to maintain the ambient temperature limits according to the values established by the standards, and thus enable the transformer to be able to deliver its nominal power without exceeding its thermal limits foreseen in its construction. In the case of rooms where ventilation is insufficient or have inadequate thermal insulation, forced ventilation is a solution to have power.
3. A combination of the two previous situations. It is common for the days with the highest power demand to be the hottest days of the year, so the transformer is subjected to a higher energy demand, with its consequent increase in temperature. At the same time, this causes the room that houses it to have a temperature higher than the recommended service value, which worsens the dissipation conditions of the equipment. Faced with this situation, forced ventilation equipment provides an excellent solution, making it possible to walk through it without any surprises.
Components and operation of forced ventilation systems
Forced ventilation equipment can be factory-supplied next to the transformer or installed on site quickly. They are composed of two supports, which have three directional axial forcers each. These brackets are installed under the coils on each side of the transformer, also including in the provision an electronic protection module for the fans (suitable for panel mounting) that works in association with the installed temperature protection control panel, providing protection and drive functionalities.
Do you need to ensure the efficiency and extend the life of your encapsulated dry transformers with adequate forced ventilation? At Miron.com.ar, we are experts in offering customized solutions. In addition, our maintenance service and transformer services guarantee comprehensive care to keep your equipment in optimal condition. Contact us today for a no-obligation consultation and find out how forced ventilation can optimize your equipment. Write to us at info@miron.com.ar or visit our section of Dry Insulation Transformers | MIRON Argentina.
