Description:

For the majority of smelting products, the cost is energy consumption. Therefore, the consumption of ore furnace transformers is increasingly valued by the smelting industry and transformer manufacturers. The following is an overview and design intent of the new type of electric furnace transformers.

User's pursuit of submerged arc furnace transformers:

　　The development of the market economy has also led to significant changes in users' expectations for the products they purchase. In the past, some users were very familiar with transformers and put forward many constraints when placing orders. If the magnetic flux density of the iron core, the current density of the winding, the weight of each part of the transformer, etc., cannot be rejected, it will have a negative impact on the overall use efficiency of the product, because the progress of materials and structures often leads to some constraints that are counterproductive. For example, the iron core: low magnetic flux density will inevitably lead to an increase in iron consumption, while no-load loss is not directly decreasing, most of which is an increasing trend. The large amount of iron core used, the increase in diameter, will lead to an increase in winding diameter, Increasing the length of each turn of wire leads to an increase in load loss, resulting in a decrease in overall usage efficiency. In recent years, there has been a significant change in user requirements, which has also promoted the development of new energy-saving calcium carbide furnace transformers. As a manufacturer of our transformers, we pursue four points: firstly, low air and load losses of the products; Secondly, the product has good reliability and a long lifespan; The third is to have a certain overload capacity (20% overload for long-term use); The fourth is to improve the supporting facilities and minimize maintenance as much as possible. According to user requirements, our company has phased out all products produced three years ago. Most orders from users are new designs, changing the appearance of the products and achieving good economic benefits for users.

Improvement of materials, structure, process, etc. of transformers:

　　A complete transformer for a submerged arc furnace is mainly divided into six parts: iron core, winding, body, oil tank, final assembly, and accessories.

• Iron core: In terms of materials, we have chosen either BaoWu Steel's 30Q130 or Nippon Steel's 30Z130 silicon steel sheet, which is basically consistent with the materials used in internationally developed countries.

• The structure adopts a fully inclined seam plate type, and the connection between the upper and lower clamps adopts a low magnetic steel plate pull plate structure, changing the previous square iron structure to ensure that there are no holes or defects on the iron chip, the magnetic flux density of each section of the iron core is consistent, and there is no distortion. In the shear process, German imported Georg shear lines are used to control the shear burrs to be less than 0.02mm (standard<0.05 is qualified), and the length tolerance per meter is less than 0.2mm, thereby increasing the lamination coefficient and reducing the gap between the seams, It avoids local overheating of the iron core, reduces product noise, no-load loss, and no-load current.

•  Winding: There is not much progress in the material of oxygen free copper electromagnetic wires, and our company mainly controls them ρ 20 ℃<0.017241, and the main control is the material and tightness of the paper insulation. The purpose is to ensure that the coil has good axial and radial stability as much as possible. The coil adopts a small oil gap, internal and external oil shields, guided cooling, and a hard paper tube structure, making the structure compact, with strong overload capacity, thermal stability, and reduced losses.For large on load voltage regulation and 110kV level products, all "8" shaped coils are wound and formed in one go, increasing coil strength and reducing eddy current losses.

• Body: All wooden components of the body are laminated wood, which increases the stiffness of the lead frame. The upper and lower pressing plates are made of cardboard or epoxy resin molded parts, which increases the insulation distance between the conductive body and the ground compared to iron pressing plates and can reduce the size of the "window height". 1、 The secondary main insulation is made of imported cardboard, which increases the strength of the main insulation. Multiple coils are packaged as a whole, improving the reliability of the product. The drying of the device body adopts Norwegian vapor phase drying equipment, which is thorough and does not damage the insulation, and has the function of flushing the device body.

• Oil tank: The oil tank adopts a folded plate type, minimizing welding seams as much as possible, increasing strength and conducting positive and negative pressure tests to ensure the reliability of product sealing. Low magnetic steel plates or magnetic shielding are used in appropriate positions to reduce additional losses caused by the magnetic field of the collector wire on the box wall. This work has achieved very good results in anti-seepage and loss reduction.

• General assembly: After the body is dry, the winding loosens and is compressed with hydraulic equipment, achieving good results. Vacuum oil injection is used to reduce bubbles in the product winding, reduce partial discharge, and increase the product life. Using new anti-aging sealing materials, the original leakage problem can be improved.

• All control wires, such as gas relays, signal thermometers, resistance thermometers, pressure relief valves, magnetic oil meters, CT, etc., are uniformly introduced into the junction box on the box, improving the overall aesthetics of the transformer.

• Attachment: The main accessory water cooler uses YS1 type oil water cooler or stainless steel spiral plate cooler, and the high-pressure casing adopts a drain type to increase the creepage distance.

• The on load tap changer adopts the "M" or "V" type from advanced domestic manufacturers. In addition to requiring remote display, there is also a remote control interface. If necessary, an online oil passing device can be added to the switch.

• The transformer oil is naphthenic anti-aging transformer oil produced in Karamay, Xinjiang, and the protection for the oil is fully enclosed (that is, the pressure relief valve is equipped with a diaphragm oil conservator)

Discussion on the Development Trend of Mineral Furnace Transformers:

　　Due to the improvement of the production process of the submerged arc furnace, it has also had a significant impact on the structure of the transformer. For example, the development of fully enclosed smelting has led to the transformer being designed as a single-phase transformer with an adjustable copper tube side outlet, on load voltage regulation, and unified cooling. Multiple sets of such products have been produced.

Several opinions on transformer maintenance:

　　It is necessary to use the suspended core after the product arrives for long-distance transportation, mainly to solve the problems of loose fasteners during transportation and user acceptance of the manufacturer's products. However, regarding routine major repairs, we believe that it is necessary to inspect and replace those mechanical wear parts according to the original major repair cycle. For operating components such as pumps, it is not necessary to suspend the core inside relatively stationary transformers for a long time. Only monitoring the changes in the gas chromatography analysis value of the oil is sufficient to grasp the condition of the transformer body, thereby saving maintenance costs and reducing the pollution of the transformer body and oil caused by the suspended core.

What is a submerged arc furnace transformer？

Definition：
A submerged arc furnace transformer is a transformer that converts the high - voltage electricity of the power grid into a low - voltage, high - current power source required for the operation of a submerged arc furnace. It is a crucial component of the submerged arc furnace equipment and is used to provide electrical energy for the ore - smelting process.

Working Principle：
It is based on the principle of electromagnetic induction. When the high - voltage alternating current from the power grid is connected to the primary winding of the submerged arc furnace transformer, an alternating magnetic field will be generated in the iron core. This alternating magnetic field will induce an electromotive force in the secondary winding. Since the secondary winding is designed to output a low - voltage and high - current, it can provide a suitable power source for the submerged arc furnace. For example, the primary winding is connected to a grid voltage of 110 kV or higher, while the secondary winding may output a low - voltage and high - current of several hundred volts to meet the working requirements of the submerged arc furnace.