The output of dry type transformer in China ranks first in the world, and the output of resin insulated transformer can reach 10000MVA every year. And the transformer also began to promote the development of low noise, energy saving direction, China's production and development of dry transformers in the manufacturing level and performance indicators have been relatively advanced in the world.
1. Temperature control system
One of the main reasons for transformer failure is due to insulation damage, and the biggest threat of insulation damage is from the winding temperature tolerance is exceeded the limit. Therefore, it is very necessary to monitor and alert the transformer in operation. Below to ttC-300 temperature control system as an example to introduce.
1.1 Automatic fan: A thermistor is embedded in the low-voltage winding at the hottest point to obtain the temperature signal, through which the fan can be adjusted when the transformer load becomes large.
The temperature will rise and the thermistor will react to it. When the temperature reaches 110 degrees Celsius, the fan will start automatically for cooling. When the temperature drops below 90 degrees Celsius, the wind picks up the temperature signal and stops.
1.2 Tripping and alarm. The PTC thermistor embedded in the low-voltage winding is used to monitor and test the temperature of the winding and the iron core. If the temperature of the winding in the transformer exceeds 155 degrees Celsius, the system will alarm the overtemperature signal.
If the temperature exceeds 170 degrees Celsius, the transformer can no longer operate at this temperature. Therefore, tripping signals will be transmitted to the secondary protection circuit, and the transformer will react quickly to make tripping actions.
1.3 display temperature: the thermistor is embedded in the low-voltage winding. Through the temperature test of the resistor, the temperature is displayed by the analog signal output of 4 to 20mA current.
If the need for computer connection can also be added to the computer interface for remote transmission, transmission distance can be up to 1200 meters. In addition, a transmitter can simultaneously monitor 31 transformers.
And thermistor signal action, overtemperature alarm and trip action can also be carried out, the temperature control of the protection system further improve the performance.
2. Protection mode
For transformer protection, the selection of shell is also very important, which needs to be carried out according to the protection requirements and the requirements of the use environment. Therefore, the form of shell is diversified.
Normally, the transformer shell will choose IP20, which is a conventional choice, mainly to prevent cats, mice, snakesks and some foreign bodies with a diameter greater than 12mm from entering the transformer, resulting in some short-circuit and other malignant accidents, and protecting the live part.
In addition, if the protection shell of outdoor transformer needs to choose IP23, in addition to the above functions, it can also protect the water droplets within the vertical Angle of 60 degrees. But in this way, it will affect the heat dissipation capacity of the transformer, so we should pay attention to the operation capacity.
3. Cooling method
The types of dry type transformers mainly include natural air type and forced air type. Natural air cooling is mainly for transformers operating continuously within the rated capacity range.
Forced air cooling can increase the output capacity of the transformer by 50%. This method is mainly applied to discontinuous load operation, or load operation due to an accident.
However, in load operation, both impedance voltage and load loss will increase unnaturally, which is not conducive to economic operation. Therefore, it is not appropriate for the transformer to operate under such load for a long time.
4. Overload capacity
Overload capacity of transformer is affected by many aspects. Therefore, the overload capacity of transformer needs to be rationally planned and utilized. Therefore, this kind of problem can be solved from the following aspects:
(1) The capacity of the transformer can be reduced appropriately. The impact overload of steel rolling and welding equipment during the working period may be considered. The capacity can be reduced through the application of the overload capacity of the transformer, which is also an effective use of the overload of the transformer.
In addition, for some lighting residential public space and some entertainment culture equipment and air conditioning and malls uneven places such as load, but also can use its overload capacity, and to the appropriate to reduce the capacity of transformer, transformer to run the main time at full load or intermittent overload condition.
(2) The reserve capacity or the number of sets can be reduced: in some places, the reserve coefficient of the transformer is required to be high, so that the transformer selected in the project has a large capacity and more sets. The overload capacity of dry deformation can be compressed when considering its reserve capacity. It can also be reduced when determining the number of standby tables.
When the transformer is in overload operation, it must pay attention to monitoring its operation temperature: if the temperature rises to 155℃ (there is an alarm), load reduction measures (minus some secondary loads) should be taken to ensure the safety of power supply for the main load.
5. Dry transformer low-voltage hazard mode and its interface coordination
Dry type transformer because there is no oil, there is no fire, explosion, pollution and other problems, so the electrical code, regulations and so on do not require that dry type transformer is placed in a separate room.
Especially with the new SC (B) 9 series, the loss and noise are reduced to a new level, which makes it possible for transformers and low voltage screens to be placed in the same distribution room.
5.1 Low-voltage standard closed bus: if closed bus (also known as plug-in bus or intensive bus slot) is selected for engineering distribution, the corresponding transformer can provide standard closed bus terminals for convenient connection with external bus.
With a case (IP20), a closed bus flange is provided on the top cover of the case; No enclosure (IP00) product, only closed bus terminal is provided.
5.2 low voltage side qualification standard rank: when the transformer and low voltage distribution panel placed side by side, for the convenience of the terminal, the connection between transformer side outlet can provide low voltage rank, usually with GGD and houndreds types product as like GCK, MNS low-voltage screen suitable, transformer factory interface to be signed with the company (hereafter called sacsc) minutes, confirm with interface and detailed size, ensure the installation smoothly.
5.3 Side outlet of low pressure standard. This kind of side outlet adopts the vertical row mode, which is similar to the horizontal row mode. When the transformer USES domino-type vertical distribution screen for vertical layout, the transformer can provide low-voltage side outlet.
In China, the dry type transformer based on resin insulation material has reached a very high output, and also occupies a place in the world, the production and sales jumped to become the world's largest. And the level of craftsmanship in the manufacturing is amazing.
The application and technical promotion of this transformer is very promising in the future, which is also due to its long-term development prospects in manufacturing. It can be summarized as follows:
Low energy consumption and low noise. Silicon steel is lower in consumption, foil winding has advantages in the structure, the ladder core joints and more rigorous than the traditional way.
The overall structure of the combined dry transformer environmental protection is higher, the promotion of these technologies, coupled with small noise, and added some new technologies and new processes, so that the future transformer more quiet and more environmentally friendly energy saving.
Good reliability performance. First of all, the reliability and quality of products have become people's pursuit of products. Through the study of each technological process, the reliability of the transformer is confirmed, and further contribute to the improvement of its life and reliability.
It is mainly based on basic research in engineering. Environmental protection characteristics certification: First of all, the standard basis of environmental protection is HD464, dry transformer in c0/C1 /C2 and other weather resistance performance, E0/E1/E2 and other environmental resistance level as well as F0/F1/F2 fire resistance level on the characteristics of research and certification.
Capacity expansion. First of all, distribution transformers are mainly used in dry type transformers, with the capacity ranging from 50KVA to 2500KVA. In the application of this kind of transformer, it begins to expand towards power transformers.
The capacity of this kind of transformer is between 10000KVA and 20000KVA, which is also caused by the expansion of urban electricity consumption and the deepening expansion of power grid area. Urban load centers are becoming more and more, and power transformers with large capacity begin to be promoted.
The combination is functional. At present, the transformer is structurally equipped with protective enclosure, air cooling and temperature calculation interface, transformer and power measurement, etc. The development of the transformer is also toward the direction of such a fully functional type. Areas of development were expanded. Distribution transformer - based field began to expand the direction of multi - field large platform.
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