It is not difficult to find suppliers of oil-immersed transformers in China. 

Open Alibaba or Made-in-China, and you'll find a large number of options. But if you're looking for a 35KV oil-immersed double-split transformer (35KV Oil Immersed Transformer Double Split) that can be used in demanding environments such as power plants and new energy substations and can operate stably for several years, it's not that easy. 

I have been engaged in the procurement and auditing of power equipment for over a decade. I have visited dozens of oil-immersed power transformer factories and been to nearly a hundred engineering sites. I have seen substandard products that started leaking oil within half a year, and also witnessed high-efficiency oil-immersed transformers operating stably for ten years in mountain power stations. Today, I'll share some practical tips with you on how to choose this type of transformer and avoid the pitfalls. 

Don't fall into the trap of low prices. 

Everyone wants to save some money when making a purchase, but I have to remind you: Saving a hundred thousand or so on a 35KV double-split oil-immersed transformer may cost you several hundred thousand to fix the problems later. 

Those oil-immersed transformers with quotations far below the market price are mostly secretly reducing their configurations. Either they simplify the iron core fixing process or replace self-adhesive transposition wires with ordinary wires. They may seem usable at first glance, but in reality, they are not up to par in terms of short-circuit resistance and sealing. Especially in high-load scenarios such as new energy booster stations and traction substations, they are prone to failure. Once there is a power outage or maintenance is needed, the losses will be significant. 

A reliable 35KV double-split oil-immersed transformer must have these five advantages. 

After covering so many live events, I've summarized five core advantages. As long as they are met, you basically won't go wrong: 

1. Reliable power supply, no disruption even if it breaks down

The most core advantage of this transformer is its split-phase design. I once saw this in a power plant where a regular oil-immersed transformer would have to stop the entire power supply if one phase broke down. But this dual-split one is different. If one phase has a problem, it can be taken out for repair separately, and the other two phases can still be used. The power outage area is much smaller, and the impact is reduced accordingly. Moreover, each phase is independently designed, so even if there is an oil leak, it won't affect the other phases. Requirements like "single-phase core extraction for maintenance" in power plants and traction substations can be fully met by this transformer, which is something ordinary transformers can't compare with. 

2. Flexible transportation and installation, can be installed in mountainous areas and on islands

When undertaking projects in mountainous areas, on islands, or in metro shield tunnel sections, transportation is a major challenge. Conventional oil-immersed power transformers are too heavy and large. The weight limits of tunnels and bridges prevent them from being transported in. 

However, the split-phase type is a three-phase split type, which can be transported separately to the site and then assembled. I was previously involved in an island photovoltaic project, and it was entirely thanks to this that the transportation problem was solved. Not only was it easy to transport, but the installation period was also short. In such special scenarios, choosing it is definitely the right choice. 

3. Strong short-circuit resistance and stable operation

Short circuits in the power grid are fatal to transformers. High-quality 35KV double-split oil-immersed transformers have independent core frames for each phase and are clamped with pull plates, capable of withstanding symmetrical short-circuit currents of 250 kA. The windings use self-adhesive transposed conductors that can "stick together" when subjected to electromagnetic forces, with bending strength over 30% higher than conventional structures. 

I once witnessed a sudden short circuit in an industrial park. The winding of a regular transformer nearby was deformed and scrapped, but the double-split one was completely unscathed. Its stability is truly reliable. 

4. Low maintenance and cost-effective operation

For operation and maintenance teams, a maintenance-free device is the best choice. This low-maintenance oil-immersed transformer (Oil Immersed Transformer with Low Maintenance) features a corrugated oil tank and a fully sealed design, eliminating the need for oil changes by opening the tank cover for 20 years, saving a lot of trouble. 

Moreover, during maintenance, only the oil of one phase needs to be drained, which is approximately one-third of the total oil volume. The cost of oil filtration is low, and the power outage maintenance time is also short. Compared with traditional oil-immersed power transformers, it can save a considerable amount of operation and maintenance costs every year. 

5. Energy-saving and noise-reducing, suitable for urban and industrial areas

Nowadays, energy conservation is highly valued. The no-load loss of this high-efficiency oil-immersed transformer is 15-25% lower than that of the S11 series, and its load loss also complies with the national first-level energy efficiency standard 

In addition, it adopts a five-column rolled core structure, which can reduce the operating noise by 3 to 5 dB. I have installed it in urban network substations and industrial parks. Even when it operates at night, the noise does not affect the surrounding areas. It is particularly suitable for these scenarios where noise is a concern. 

Just pick these scenes. 

Not all projects require this model, but in the following scenarios, choosing it is definitely the right choice: 35 kV urban ring network cabinets for main transformers, three-phase traction transformers in traction power supply systems, three-phase box transformers in photovoltaic/wind power new energy booster stations; substations in mountainous areas, islands, and shield tunnel sections where transportation is inconvenient; user substations such as petrochemical plants and data centers that require "single-phase withdrawal for maintenance" or "phased expansion". 

When looking for suppliers, these three questions must be asked. 

When negotiating with suppliers, don't just ask about the price. Make sure to clarify these three questions to determine if they are reliable: 

What are the test data for your 35KV double-split oil-immersed transformer's resistance to short-circuit current? Can you provide an authoritative test report? (Reputable manufacturers all have complete data to ensure they can withstand a symmetrical short-circuit current of 250 kA). 

2. Does your high-efficiency oil-immersed transformer meet the GB 20052-2020 Class 1 energy efficiency standard? Can you provide the energy efficiency test report? (To avoid purchasing products with falsely marked energy efficiency.) 

For special transportation scenarios such as mountainous areas and islands, can you provide a complete disassembled transportation and on-site installation guidance plan? (This tests the engineering service capabilities of the manufacturer.) 

To be honest, in the end. 

The 35KV double-split oil-immersed transformer is a core device in the power system. Its reliability directly determines whether the project can operate stably and make profits. Choosing it is not just about picking a piece of equipment, but also about selecting a long-term cooperative partner. 

I hope my experiences can help you avoid pitfalls and select the equipment that suits your project. A good low-maintenance oil-immersed transformer not only ensures stable power supply but also helps you save on operation and maintenance costs as well as electricity bills, providing a solid support for the long-term profitability of your project.