The no-load performance of a five-stage laminated core transformer has been analyzed by Shang Yafei from Xinjiang Special Transformer Co., Ltd.'s Transformer Factory in Changji, Xinjiang. He explored how the five-stage joint core reduces no-load losses, no-load currents, and noise, highlighting that employing this core structure significantly enhances the no-load performance of transformers.
Energy conservation and emission reduction are key directions in transformer development, with improvements in core lamination structures being a major pathway to reducing losses. Many advanced countries utilize five-stage joint core technology, which has notably improved core no-load performance compared to the traditional two-stage joints commonly used in China. When our factory imported the TUG M H800×5 000 automatic core cross-cutting line from German Georg Company in 1998, it enabled us to process silicon steel sheets with angles of ±45°. This equipment could automatically cut three, five, and seven-stage seam silicon steel sheets. After adopting the five-stage joint core structure, our products showed significant drops in no-load losses and no-load currents, along with a reduction in noise levels. Particularly for large-capacity products, the effects were more pronounced. This paper provides an overview of the structural form of the five-stage seam core, the mechanisms behind its energy-saving properties, and the practical energy-saving outcomes.
The two-stage or three-stage joint lamination structures typically used domestically involve staggering the core laminations at specific distances, forming two parallel joints in the staggered areas. The magnetic flux distribution at the core joints resembles what is depicted in Figure 1. In this setup, most of the magnetic flux in the lamination passes through bridging laminations, and the magnetic density at the joint area is approximately 22 times that of the core column. However, in a three-stage seam core, the magnetic flux at the ends of the silicon steel sheets passes through two layers of bridging laminations, with each layer spanning the end of the lamination. The relationship between the local magnetic flux density B and the number of joints N can be expressed as:
\[ B = \frac{N}{2} \times B_{\text{column}} \]
This indicates that increasing the number of joints reduces the magnetic density and thus the associated losses. Despite this, the number of laminated sheets increases with the number of lamination stages, reducing the production efficiency of silicon steel sheet cutting and core lamination. This challenge can be addressed with advanced cutting equipment and lamination processes, along with selecting the appropriate seam level. Through nearly two years of production experience, we believe that five-stage joints are better suited for kV-class transformers, offering higher production efficiency than ordinary two-stage or three-stage joints.
Comparing the local losses and no-load currents of five-stage versus three-stage joints, the former shows a marked improvement. The no-load loss of the transformer can be expressed as \( P = K \), where \( P \) depends on the core material, magnetic density, frequency unit loss, core weight, and other factors. For kV-grade products, the total coefficient \( K \) is typically around 1.12. Calculations show that the no-load loss coefficient should be approximately 1.08, but due to efficient stacking and minimal burrs during cutting, the actual coefficient is closer to 1.05. This translates to a 5-8% reduction in no-load loss and over 30% reduction in no-load current, showcasing impressive energy savings.
In addition to these benefits, the five-stage seam core offers other advantages. Firstly, regarding noise, the primary source of transformer noise is the magnetostriction of the silicon steel sheets, but magnetic attraction at the joints also contributes. The five-stage structure reduces the length of the joint gaps and the magnetic density, thereby lowering noise levels by approximately 3 dB compared to three-stage joints. Secondly, in terms of production efficiency, the use of advanced cutting equipment allows for up to seven-stage single-piece stacking. Furthermore, the core pieces have precise positioning holes, enabling faster assembly and significantly boosting production efficiency. Lastly, material savings are evident due to the reduced joint gaps and optimized core design, leading to a decreased need for electromagnetic wires.
To demonstrate these advantages, we compared six kV-class transformers—three using three-stage joints and three using five-stage single-piece lamination. Results showed an average 8% reduction in no-load loss, a 50% drop in no-load current, and a 4 dB decrease in noise for the five-stage core compared to the three-stage core.
In conclusion, the five-stage seam core excels in low losses, low noise, and excellent processability. Its adoption contributes to energy savings, improved power supply quality, and reduced environmental noise pollution. Our factory’s adoption of this structure has led to a 2% reduction in no-load loss and a more than 8% drop in no-load loss for kV-grade products, accompanied by a 30% reduction in no-load current and a 4 dB noise decrease. Given the current core materials, utilizing a five-stage seam lamination structure is undoubtedly the optimal production method and an ideal replacement for traditional two-stage and three-stage joint cores.
Here you can find the related products in Recordable Sound module, we are professional manufacturer of Greeting Card Sound Module, Recordable Sound Module, Recordable Musical Module. We focused on international export product development, production and sales. We have improved quality control processes of Recordable sound module to ensure each export qualified product.
If you want to know more about the products in Recordable sound module, please click the product details to view parameters, models, pictures, prices and other information about Greeting Card Sound Module, Recordable Sound Module, Recordable Musical Module.
Whatever you are a group or individual, we will do our best to provide you with accurate and comprehensive message about Recordable sound module!
Greeting Cards Sound Module, Recordable Sound Module, Recordable Musical Module
AST Industry Co.,LTD , https://www.astsoundchip.com