Manufacturing a qualified oil-immersed transformer is never a simple job. From raw material processing to finished product delivery, the whole production involves dozens of sophisticated procedures. Every stable and durable power transformer relies on standardized, meticulous craftsmanship. As a professional manufacturer focusing on transformer R&D and production, Hebei Hozee Electric Co., Ltd. mainly produces oil-immersed transformers, dry-type transformers, single-phase transformers, as well as laminated iron cores and single-phase winding cores. We strictly control every production detail for all power equipment. Whether it is a conventional oil-immersed transformer or a customized 630KVA Dry Type Transformer, we always adhere to strict production standards to ensure long-term stable operation of equipment. Today, we simplify the complex manufacturing flow of oil-immersed transformers into 10 intuitive core processes for your reference.
01. Coil Winding
In accordance with official design drawings, high-quality oxygen-free copper wires or copper foils are adopted for winding high-voltage and low-voltage coils. All finished coils will be tested item by item strictly. We never allow unqualified products to enter the next process, ensuring all technical indicators meet design and industry requirements.
02. Coil Assembly
The finished coils are sleeved on the iron core columns in a standard concentric circle layout. During assembly, we strictly control the gap uniformity between coils and iron cores, as well as between adjacent coils. After assembly, workers will carefully check the symmetry and height consistency of all coils to avoid assembly errors.
03. Iron Core Lamination
After the coils are fully assembled, high-permeability cold-rolled silicon steel sheets are used for the lamination and assembly of the upper iron yoke. The flatness of each layer is measured during lamination. Tight lamination and tiny splicing gaps can effectively reduce the no-load loss of the transformer and improve overall energy efficiency.
04. Transformer Body Assembly
We integrate the iron core and coils into a complete transformer body, including placing insulating gaskets and installing supporting clamps. All fastening bolts are locked with torque wrenches according to standard torque values. This standard operation prevents component loosening caused by vibration during long-distance transportation and daily operation.
05. Lead Connection
High and low voltage leads are assembled and connected to tap changers as required. We guarantee excellent insulation between all leads. All welding positions are carefully cleaned and wrapped with professional insulating materials to eliminate potential safety hazards such as short circuits.
06. Vacuum Drying
The assembled transformer body is sent to a vacuum oven for high-temperature dehumidification to completely remove internal moisture from coils, insulating paper and gaskets. Moisture will greatly reduce the insulation strength of transformers. This step is crucial to guarantee product performance and extend equipment service life.
07. Lifting and Fastening
The dried transformer body is lifted into the oil tank for assembly and fastening. The whole sealing and assembling process must be completed within the specified time to prevent the dry body from absorbing moisture again and damaging the insulation structure.
08. Oil Filling Process
Professional vacuum oil filters are used to heat and filter insulating oil, removing impurities and trace moisture. When the oil level submerges the iron core, oil filling will be suspended. The transformer is sent to the vacuum oven again for vacuum degassing and dehumidification, and finally filled with insulating oil to the standard level.
09. Pressure Inspection
After oil filling is completed, a pneumatic sealing test is carried out to check all welds and gaskets for oil leakage. The transformer cannot be put into operation immediately. It needs to stand for more than 24 hours to allow the insulating oil to fully infiltrate insulating materials and discharge residual tiny bubbles.
10. Factory Delivery Test
Factory test is the strictest final quality inspection step. In addition to random inspections during production, every transformer will undergo full-item performance tests before delivery. All test data must meet or exceed national standards. Only qualified products can be put into storage and delivered to customers. At Hebei Hozee Electric Co., Ltd., not only oil-immersed transformers, but also our hot-selling 630KVA Dry Type Transformer and other series products are all inspected with the same strict standards.
Material costs can be calculated, but craftsmanship depends on ingenuity. Every process of transformer manufacturing concerns the safety and stability of long-term operation. As a professional transformer manufacturer, Hebei Hozee Electric Co., Ltd. always believes that product delivery is only the starting point of service. We focus on the long-term stable operation of equipment for 20 to 30 years. We do not pursue fast output, but reliable quality. With stable craftsmanship and consistent quality, we provide trustworthy power transformer solutions for global users.