Why we think of rapeseed oil
Mineral transformer insulation oil has been used in oil-immersed transformers for its excellent electrical and thermal properties for nearly a hundred years, and it is durable because of its large output, good quality and superior technical and economic indicators. However, the mineral insulating oil itself has shortcomings, such as non-renewable, non-biodegradable, easy to pollute the environment when leaking, low flash point and poor fire and flame retardant. At the same time, mineral transformer oil is produced from petroleum, at present, the shortage of petroleum resources in the world, seeking to replace mineral transformer oil products has become the main issue at present.
Talk about vegetable insulating oils
Plant insulating oil is prepared from natural oil crops by pressing (rapeseed oil as an example below), refining and modifying processes, and its molecules are composed of triglycerides, triglycerides and three long chain fatty acids attached to a glycerol center, which can be rapidly and completely biodegradable, non-toxic in oral and aquatic biological tests, and has better environmental and health properties than mineral oil. It has good electrical properties, high ignition point, broad source of raw materials, and has the advantages of renewable and biodegradable. At present, the United States, the European Union and Japan have begun to replace mineral transformer oil with plant insulation oil.
What are the key points of innovation
Innovative structural design. The plant rapeseed oil high overload amorphous alloy transformer is different from the traditional transformer in structure. Due to the external stress of amorphous alloy core, the loss will increase by about 60%. The noise also increases, which seriously affects its performance. Therefore, the amorphous alloy core structure design is different from the traditional transformer core main support structure, in order to avoid the amorphous alloy core force. The core of the plant rapeseed oil high overload amorphous alloy transformer is suspended on the winding, and the oil-immersed high voltage winding adopts the winding glass wire adhesive tape to heat solidified rigid body structure, and its axial mechanical strength is high enough to "hold up" the amorphous alloy core. The winding is supported on the lower clamp by the pad. In addition, due to the three-phase five-column structure of the amorphous alloy core, the length of the transformer is large. Considering that the span of the lifting plate is too large, the lateral tension of the lifting rope causes the deformation of the lifting plate, so the lifting design is to pull the upper clamp by lifting, and the side clamp is connected to the upper and lower clamp. Therefore, the strength of the upper and lower clips is the key to structural design. Plant rapeseed oil high overload amorphous alloy transformer adopts frame structure. There are two types of frame: integral frame and connected frame. The connecting frame is used, which is conducive to controlling the assembly error. The clamp is designed with an overturning structure.
Optimize the coil process. Product coil low pressure adopts double concentric rectangle, outsourcing weft less glass adhesive tape; The high pressure adopts multi-layer concentric rectangular structure coil, and the high and low pressure coil is wound together with tension device, improving the shaping and pressing process, etc., and the oil immersed type is cured by glass wire adhesive tape at high temperature, which effectively reduces the local discharge and increases the mechanical strength and the ability to resist short circuit impact.
Short-circuit resistance enhanced. The winding of the plant insulation oil high-overload amorphous alloy transformer is a rectangular structure, the force is not as uniform as that of the round winding, and it is easy to deform when it is subjected to short circuit electrical force. In this way, the axial and radial short-circuit electric force of the rectangular winding is more severe than that of the circular winding. The product compacts the winding axially in the upper and lower clips through the pad. The high voltage winding is a rigid body structure of epoxy glass adhesive tape encapsulation, which is sufficient to withstand the core mass and the axial electric force generated during short circuit. The low-voltage winding is made of copper foil, oven-cured, and has high mechanical strength. The rectangular winding is analyzed by Ansys structure analysis software. It is concluded that the radial deformation in long axis direction is the most serious when rectangular winding is subjected to short circuit electric force. Therefore, the difference between long axis and short axis should be avoided in design. In the assembly process, the support pad is padded in the direction of the long axis and the short axis to increase its strength.
In addition, stainless steel is bent into a 
type oil passage to enhance the flow of vegetable oil.
The hysteresis noise is obvious. The use of plant insulating oil instead of traditional mineral oil, vegetable oil viscosity is large, the fluidity is relatively poor, to a certain extent, can reduce the speed and frequency of sound wave propagation, to achieve the effect of hysteresis noise.
Main technical and economic indicators: 1.the no-load loss of the product is reduced by more than 80% compared with the type 11 product, and the load loss is reduced by more than 15% compared with the type 11 product.
2.two times the rated load continuous operation time of 6 hours, 1.5 times the rated load can run for a long time, which can effectively solve the problem of long-term overload operation of the transformer, and avoid the transformer burn phenomenon caused by short time high overload.
3.The noise level is leading, more than 8 decibels lower than the national standard
Mainly meet the following requirements
Power transformers - Part 1: General
Power transformers - Part 2: Temperature rise
Power transformers - Part 3: Insulation levels, insulation tests and external insulation air gaps
Power transformers - Part 4: Lightning shock and operational shock test guidelines for power transformers and reactors
Power transformers - Part 5: Ability to withstand short circuits
Power transformers - Part 10: Determination of sound levels
Technical parameters and requirements of oil-immersed amorphous alloy core distribution transformer
Energy efficiency limits and energy efficiency grades of three-phase distribution transformers
Technical guidelines for distribution transformers with high overload capacity for rural power grids
Quality standard for soybean vegetable oil transformers
The amorphous change of rapeseed oil is promising
Rapeseed oil has high biodegradation rate, no harm to the environment, and meets the new environmental protection requirements; Plant rapeseed oil transformer has good flame retardancy and is suitable for areas with high fire protection requirements; Rapeseed oil paper fit better, the electric field distribution is more uniform; Rapeseed oil can absorb moisture contained in aging insulation paper, and prevent the splitting of long fiber molecules when in contact with heat. These characteristics can increase the load capacity and extend the insulation life of transformers, reducing the life cycle cost; Plant rapeseed oil comes from a wide range of sources and can be planted on a large scale to increase production and reduce the production cost of transformers. With the further development of plant rapeseed oil technology, the unification of standards, the improvement of production, and the reduction of costs, this kind of plant insulation oil transformer that meets the requirements of environmental protection, is safe and reliable, and uses renewable resources will have a broad space for development. (Article from Amorphous China)