Oil-Immersed & Dry-Type Transformers: Top 10 FAQs from Foreign Customers

As a professional foreign trade company focusing on power transmission and distribution equipment, we have been serving global customers for many years. In the communication process with overseas clients, we found that most customers have common questions about our core products — oil-immersed transformers and dry-type transformers. These questions involve product selection, performance parameters, installation, maintenance, certification and other aspects, which are also the key factors affecting customers' purchasing decisions. Today, we sort out the top 10 most frequently asked questions, and give detailed and professional answers, hoping to help every foreign customer better understand our products and make more suitable purchasing choices.

First of all, let's briefly review the core positioning of our two main transformers. Oil-immersed transformers take mineral oil as the insulation and cooling medium, which is a traditional and mature power distribution solution, suitable for large-capacity, high-voltage and outdoor application scenarios; Dry-type transformers use epoxy resin and other solid insulation materials, focusing on fire prevention, environmental protection and maintenance-free, which is more suitable for indoor, personnel-intensive and special environmental scenarios. The following answers will combine the characteristics of the two products and the actual needs of overseas projects to solve your doubts one by one.

Q1: What is the difference between oil-immersed transformers and dry-type transformers in terms of insulation and cooling methods, and how to choose according to the project scenario? This is the most frequently asked question by overseas customers. In terms of insulation method, the winding and iron core of oil-immersed transformers are immersed in insulating oil, and the oil serves as both insulating medium and cooling medium; The windings of dry-type transformers are treated by epoxy resin casting or impregnation, and air convection is used for heat dissipation, without the need for insulating oil. In terms of cooling method, oil-immersed transformers have two common cooling methods: ONAN (natural oil circulation natural cooling) and ONAF (natural oil circulation forced air cooling), which have good heat dissipation effect and are suitable for long-term continuous operation of large capacity; Dry-type transformers mainly rely on natural air cooling, and some large dry-type transformers will be equipped with forced air cooling devices (AF) to improve heat dissipation efficiency. In terms of selection, if your project is an outdoor industrial park, high-voltage power transmission line or large-scale factory with large capacity demand (more than 1000kVA), oil-immersed transformers are recommended, which have better heat dissipation and overload capacity; If it is an indoor scene such as a data center, commercial building, hospital or school with high fire protection requirements and limited space, dry-type transformers are more suitable, which have no oil leakage risk and are safer and more environmentally friendly

Q2: What is the capacity range of your oil-immersed transformers and dry-type transformers, and can they be customized according to the special needs of overseas projects? Our oil-immersed transformers have a wide capacity range, from several hundred kVA to several hundred MVA, which can fully meet the needs of high-voltage and large-capacity overseas industrial projects, such as new energy power generation, large-scale industrial parks and high-voltage power transmission projects; The capacity range of dry-type transformers is from several kVA to several MVA, which is suitable for medium and low capacity scenarios such as commercial buildings, data centers and small factories. In addition, we support full customization according to the special needs of overseas customers. For example, for projects in the Middle East with high temperature, high humidity and more sand and dust, we can customize oil-immersed transformers with enhanced anti-corrosion and moisture-proof performance, or dry-type transformers with better dust-proof effect; For projects in Europe and America that need to adapt to local voltage standards (such as 415V in the Middle East and 480V in North America), we can adjust the transformation ratio to ensure that the product is perfectly compatible with the local power grid

Q3: What international certifications do your transformers have, and can they meet the local safety and power standards of overseas projects? This is a key issue concerned by overseas customers, especially those in Europe, America, the Middle East and other regions. All our transformers have passed international authoritative certifications such as IEC, UL, CSA and TUV, and fully comply with the local safety and power standards of different countries and regions. For example, products exported to the European Union meet the CE certification requirements, ensuring compliance with the EU's safety, health and environmental protection standards; Products exported to North America have passed UL and CSA certifications, adapting to the local power grid and safety regulations; Products exported to the Middle East have passed SASO certification, which can perfectly match the local industrial power grid standards. At the same time, we can provide corresponding certification documents according to the needs of customers to ensure the smooth customs clearance of goods and the normal operation of projects

Q4: What is the service life of oil-immersed transformers and dry-type transformers, and what maintenance work is needed during operation? Under normal maintenance conditions, the service life of our oil-immersed transformers can reach more than 20-30 years, and the service life of dry-type transformers can reach 15-25 years. If customized according to special requirements (such as using high-quality insulation materials and optimizing the structure), the service life can be further extended. In terms of maintenance, oil-immersed transformers need regular oil quality inspection, oil filtration and replacement, because the insulation and cooling performance of insulating oil will decrease after long-term use, and regular maintenance can ensure the stable operation of the product; Dry-type transformers have the advantage of almost maintenance-free, and only need to do a good job in dust prevention and ventilation regularly, check the surface of windings and iron cores for damage, and clean up dust and debris, which is more suitable for areas with limited maintenance resources overseas

Q5: How to solve the transportation problem of oil-immersed transformers? Because oil-immersed transformers are heavy and have strict transportation requirements, especially high-voltage large-capacity transformers. We have rich experience in overseas transportation and have established long-term cooperative relations with well-known international logistics companies. For oil-immersed transformers, we will take professional packaging measures, such as using shockproof packaging materials, fixing the transformer body to prevent damage during transportation; For large-capacity products that are difficult to transport, we can also adopt the way of split transportation, transport the iron core, winding and oil tank separately, and then assemble them on site by our professional technicians. At the same time, we will provide detailed transportation guidelines and documents to ensure that the goods can be transported to the project site safely and on time.

Q6: Do your transformers have the function of energy saving and consumption reduction, and what are the specific energy saving indicators? With the global emphasis on environmental protection and energy saving, more and more overseas customers pay attention to the energy saving performance of transformers. Our oil-immersed transformers and dry-type transformers all adopt energy-saving design. For oil-immersed transformers, we use high-quality silicon steel sheets and optimize the winding structure to reduce no-load loss and load loss. The energy saving efficiency can reach more than 98%, which can greatly reduce the long-term operation cost of customers; For dry-type transformers, we adopt epoxy resin insulation material with low loss, optimize the magnetic circuit structure, and the no-load loss is reduced by 15%-20% compared with ordinary dry-type transformers, which fully meets the national energy efficiency standard GB 20052-2020 and the relevant energy saving requirements of overseas countries

Q7: What should we pay attention to when installing oil-immersed transformers and dry-type transformers overseas? For the installation of oil-immersed transformers, it is necessary to choose an open and flat outdoor area, reserve enough maintenance space around, and configure corresponding fire-fighting facilities (such as oil separation pools and fire-extinguishing systems) because of the flammability of insulating oil; At the same time, attention should be paid to the sealing performance of the oil tank to prevent oil leakage. For the installation of dry-type transformers, it is necessary to choose a dry, clean and well-ventilated indoor environment, avoid installation in areas with high humidity, dust and corrosive gas, and ensure that the installation surface is flat to reduce vibration during operation. In addition, we will provide detailed installation manuals in English, and send professional technicians to the site for installation guidance if customers need it, ensuring that the installation work is carried out smoothly and the product can operate normally after installation

Q8: What should I do if the transformer fails during operation overseas? We have a complete after-sales service system to solve the failure problem for overseas customers in a timely manner. If the transformer fails during operation, customers can contact our after-sales service team through email, phone or online consultation at any time. Our professional technicians will first communicate with customers to understand the specific situation of the failure, and provide remote troubleshooting guidance. If the problem cannot be solved remotely, we will arrange after-sales personnel to go to the site for maintenance as soon as possible, and prepare corresponding spare parts in advance to shorten the maintenance cycle. At the same time, we promise that the maintenance response time for urgent failures will not exceed 24 hours, and the on-site maintenance will be arranged within 3-7 working days according to the regional distance, ensuring that the impact of the failure on the project is minimized.

Q9: What is the warranty period of your transformers, and what scope does the warranty cover? The warranty period of our oil-immersed transformers and dry-type transformers is 2 years from the date of installation and commissioning. During the warranty period, if the product has quality problems (excluding man-made damage, improper use and damage caused by force majeure), we will provide free maintenance, replacement of spare parts and other services. The warranty scope includes the main body of the transformer, windings, iron cores, cooling devices and other key components. After the warranty period expires, we will still provide lifelong maintenance services, and only charge reasonable fees for spare parts and maintenance labor, ensuring that customers have no worries about the later use of the product.

Q10: Can you provide supporting products such as distribution boxes and substations while providing transformers? Yes, our company's main products include oil-immersed transformers, dry-type transformers, distribution boxes and substations, which can provide one-stop power transmission and distribution solutions for overseas customers. The distribution boxes we produce are matched with transformers, with reasonable structure, safe and reliable performance, and can be customized according to the power distribution needs of the project; The substation integrates transformers, distribution boxes, control devices and other components, which can be directly installed and used on site, greatly shortening the project construction cycle. We can provide integrated design, production, installation and after-sales services according to the overall needs of the customer's project, saving customers' time and cost.

The above are the 10 most frequently asked questions by overseas customers about our transformers. If you have other questions or special needs, please feel free to contact us. We will always adhere to the principle of customer-centric, provide you with high-quality products and professional services, and work together with you to promote the smooth progress of the project.