When transmitting electricity over long distances, it is very important to minimize its losses. Therefore, the energy generated by the generators must be correctly converted in order to obtain a higher voltage. For these purposes, a power oil transformer is installed in special substations.
Content
- Components of the structure
- Operating principle
- Temperature regime
- Correct operation and maintenance
Components of the structure
High-voltage power lines with a voltage of more than 6 thousand volts are protected by special devices that convert alternating electric current and protect networks from serious overvoltage. There are two types of such devices:
- conventional transformers;
- autotransformers.
Both varieties have similar design and functionality. The standard transformer design includes the following components:
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Ferromagnetic core. It is enclosed in a special durable case that does not allow an aggressive environment to damage it. - Winding. It comes in copper and aluminum, has round or rectangular sections. The concentric winding is in the form of cylinders located one in the other. Several layers of low voltage winding are located close to the core. The high voltage helical winding is installed on a special cylinder that acts as an insulator. The beams on which the winding is located have special protection.
- Gas relay. Being in the pipeline between the main and the expansion tank, it passes all the gas generated during the heating of the oil. The relay is activated even with minimal gassing. If the volume of gas increases, light and sound sensors are notified of this. In the case when a lot of gas is generated, in order to prevent the decomposition of oil substances, the switches in the entire transformer are automatically triggered.
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Thermometer well. A thermometer is required to continuously monitor the temperature of the surface layers of the oil. - Air Dryer. Prevents moisture from the air from getting into the oil and deteriorating its dielectric parameters.
- Exhaust pipe. In order for the oil to flow in the right amount, one end of the pipe is connected to the main tank of the transformer, the second is at a level just above the expander.
- Safety diaphragm. Fastened to the edge of the exhaust pipe, performs a protective function in the event of an emergency power surge. Some devices may use a bellows or valve elements instead of a diaphragm.
- Bushings. With their help, the safe operation of the device is ensured. For ease of operation, the device is equipped with a handle on the tank lid.
The device of the oil transformer provides for the presence of a cooling and magnetic system in it. The main distinguishing feature of such a device from an autotransformer is its small size, due to which the use of an oil transformer becomes convenient both on the street and in technical rooms of any size.
Operating principle
The operation of a device that converts a current is based on the principle of electromagnetic induction. An alternating voltage current flows into the winding, creating an alternating magnetic field. The latter contributes to the further formation of electric current.
Oil with high dielectric properties is poured into a tank equipped with valves and a screw cap. A shut-off valve at the bottom allows oil sampling for analysis. To increase the surface of the tank, metal plates can be used to speed up the heat transfer procedure between the oil and the outer air layer.
Once in the tank, the oil begins to move along the inner and outer circle. The function of the first circle is performed by two collectors forming a radiator.
The radiator temperature can be lowered naturally or with the help of a specially provided ventilation system. Such a system, on the one hand, effectively cools the equipment, on the other hand, it reduces its load performance by an average of 25%.
Temperature regime
The oil circulating inside the tank, while heating and cooling, constantly changes its volume within a given range. For the timely compensation of volume fluctuations in the transformer there is an expansion tank with an oil indicator. Thanks to the principle of communicating vessels used during its installation and a transparent graduated glass, the process of monitoring the oil level in the device is as simple as possible.
During the operation of the power transformer, the oil temperature reaches very high values, therefore, when it cools, a huge amount of heat is released into the atmosphere.
The development of modern industrial technologies made it possible to use the released thermal energy for heating buildings located near operating transformer substations.
Correct operation and maintenance
The key to the long-term operation of an oil-immersed transformer is the observance of all norms of its use, prescribed in the instructions. For an appliance to function smoothly, it must be subjected to:
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preventive examination; - technical inspection;
- unscheduled repairs.
During these works, specialists check the operating device for the presence of extraneous noise and excessive vibrations, check the number of switchings with the data displayed on the meters. The frequency of inspections of oil-immersed transformers depends on the way they work. If the operation process is supervised by professionals, the inspection should be carried out daily. In cases with autonomously operating devices, three checks per month are sufficient.
