Key Points For Selecting Oil-immersed Transformers

Load properties:
1) When there are a large number of primary or secondary loads, it is recommended to install two or more transformers. When any one of the transformers is disconnected, the capacity of the remaining transformers can meet the power consumption of the primary and secondary loads. The primary and secondary loads should be concentrated as much as possible and should not be too scattered.
2) When the seasonal load capacity is large, a dedicated transformer should be installed. Such as the load of air-conditioning refrigerators and electric heating loads in large civil buildings.
3) When the centralized load is large, a special transformer should be installed. Such as large heating equipment, large X-ray machines, arc furnaces, etc.
4) When the lighting load is large or the use of a shared transformer for power and lighting seriously affects the lighting quality and bulb life, a dedicated lighting transformer can be installed. Normally, power and lighting share a transformer.
Usage environment:
Under normal medium conditions, oil-immersed transformers or dry-type transformers can be used, such as independent or attached substations in industrial and mining enterprises, agriculture, independent substations in residential areas, etc. Available transformers include S8, S9, S10, SC (B) 9, SC (B) 10, etc.
Temperature environment:
① Maintain long-term stability at 220℃.
② Can withstand short-term operation at a temperature of 350°C.
③ Maintain stable performance within a wide range of temperature and humidity.
④ It will not melt, flow or support combustion at a temperature of 250℃.
⑤ At a temperature of 750℃, no toxic or corrosive gases will be released.
Electricity load:
1) The capacity of the distribution transformer should be calculated based on the capacity of various electrical equipment and the calculated load (generally excluding fire protection load). The compensated apparent capacity is the basis for selecting the capacity and number of transformers. Generally, the load factor of the transformer is about 85%. This method is relatively simple and can be used to estimate capacity.
2) In GB/T17468-1998 "Guidelines for Selection of Power Transformers", it is recommended that the capacity selection of distribution transformers should be based on GB/T15164-94 "Guidelines for Loading of Oil-immersed Power Transformers" or GB/T17211-1998 "Dry Type Power Transformer Loading Guidelines" and calculate the load to determine its capacity. The above two guidelines provide computer programs and normal cycle load diagrams to determine distribution transformer sizing.