The advantages of oil-immersed transformers

(1) Oil-immersed transformers are transformers that use transformer oil as a heat dissipation medium. The use of oil-immersed transformers in power systems in power transmission and distribution projects has been used for hundreds of years. Oil immersed power transformers are one of the most widely used electrical equipment in the world today because of their simple product structure, long pre-production history, rich experience in production and operation, and reliable operation. Most transformers operating in the power system are oil-immersed transformers. The dry-type transformer that does not use transformer oil and uses air as a heat dissipation medium.

(2) Oil-immersed transformers use transformer oil as a cooling medium. The heat generated during the operation of the transformer is conducted by the transformer oil to the metal case and announced. It has the advantages of fast heat dissipation, uniform conduction and oil insulation. However, the oil itself has the defects of low heat resistance, flammability and aging, so there are many specific requirements when using transformer oil as a cooling medium. For example: the construction of the transformer needs to satisfy the requirements of the fire rating for the construction of fire protection standards. Oil-immersed transformers is necessary to prevent the extension of the fire due to oil activity under fire conditions; it is necessary to have a rescue method to remedy the oil fire; it is necessary to have Oil storage tank equipment to prevent environmental pollution when oil leakage occurs; there should be inspection operations to monitor the aging of insulating oil and regular oil regeneration operations during normal operations. According to the rules of “Planning Standards for Substations of 10KV and Below”: “The fire resistance rating of the fuel transformer oil immersed  transformer room should be a first level . The oil-immersed transformer room should be equipped with oil-blocking equipment. Each three-phase transformer with an oil capacity of 100Kg and above in the indoor substation should be in its own transformer room.” Also, the outline of the fuel-oil-immersed transformer and transformer room walls and doors have strict clearance requirements. Various earth structures and fire separation walls, oil storage tanks of oil-immersed transformer substations are planned because of the flammability and mobility of oil. In addition, “when the transformer room is located in the building, the door of the fuel-oil-immersed power transformer room should be a Class A fire door.” In this way, each substation’s planned construction investment to prevent fire is naturally much larger.

(3) With the continuous development of scientific skills and the advancement of data science, these years have presented fully-enclosed oil-immersed transformers, such as fully-sealed S9-M, S10-M, S11-M and other series distribution transformers which use corrugated oil tanks The thermal expansion and contraction of oil-immersed transformers oil is adjusted by the elasticity of the corrugated sheet and blocked by the air which completely overcomes the problem of oil leakage; the fully enclosed oil-immersed transformer has no breathing apparatus and handles the problem of oil oxidation caused by oil and air touching. Extended service life; small footprint, energy-saving, preemptive functional skills and excellent cold-rolled silicon steel sheet with excellent magnetic permeability grain orientation, compared with S9 type with the same capacity, no-load loss reduced by 30%, and no-load current decreased by 40 ~ 70%, noise reduction by 5 ~ 8 dB (A). However, because it still uses oil as a cooling medium. It is also necessary to abide by the relevant standard requirements of oil-immersed transformers when planning.