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Advantages, Disadvantages and Differences of Dry Type Transformers and Oil Immersed Type Transformer

2021
Issuing time:2018-10-25 16:43Author:Zhejiang Keshuo Electric Co., Ltd.

Advantages and disadvantages of dry and oil immersed transformers

Drying on the price becomes more expensive than oil.

In terms of capacity, large-capacity oils become more dry than dry.

Drying is required in complex buildings (basement, floor, roof, etc.) and in crowded locations. The oil change is used in an independent substation.

The transformer inside the box is generally box-changed. Outdoor temporary electricity generally uses oil change.

In the construction, the dry change and the oil change are selected according to the space. When the space is large, the oil change can be selected, and when the space is relatively crowded, the dry change is selected.

The regional climate is relatively humid and hot, and it is easy to use oil. If dry change is used, forced air cooling must be provided.

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1, appearance

  The package type is different, the dry type transformer can directly see the iron core and the coil, and the oil type transformer can only see the outer casing of the transformer;

2, the lead form is different

Dry-type transformers mostly use silicone rubber bushings, while oil-type transformers mostly use porcelain bushings;

3, different capacity and voltage

Dry-type transformers are generally suitable for power distribution. The capacity is mostly below 1600KVA, the voltage is below 10KV, and some can achieve 35KV voltage level. The oil-type transformer can do all the capacity from small to large, and the voltage level also does all. Voltage; the UHV 1000KV test line under construction in China must be an oil-type transformer.

4, insulation and heat are not the same

Dry-type transformers are generally insulated with resin, relying on natural air-cooling, large-capacity cooling by fan, and oil-type transformers are insulated by insulating oil. The insulation of the oil inside the transformer will generate a tropical-to-transformer radiator (chip). Cooling on.

5. Applicable places

Dry-type transformers are mostly used in places where “fireproof and explosion-proof” are required. Generally, large-scale buildings and high-rise buildings are easy to adopt; while oil-type transformers may cause oil to be ejected or leaked after “fault”, which is mostly used outdoors. There is also a site where the site "excavation oil pool" is dug.

6, the ability to withstand the load is different

Generally, dry-type transformers should be operated at rated capacity, while oil-type transformers have better overload capability.

7, the cost is not the same

For transformers of the same capacity, the purchase price of dry-type transformers is much higher than that of oil-type transformers.

Dry type transformers generally start with SC (epoxy resin cast encapsulation), SCR (non-epoxy cast solid insulation encapsulation), SG (open)

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The difference between dry type transformer and oil immersed type transformer

"Of course, the same is true for power transformers, there will be iron cores for magnetic circuits, which are used as windings for circuits. The biggest difference is in "oil type" and "dry type". That is to say, the cooling medium of the two is different. The former uses transformer oil (and of course other oils such as beta oil) as the cooling and insulating medium, and the latter uses air or other gases such as SF6 as the cooling medium. The oil change is the body composed of the iron core and the winding. In a fuel tank filled with transformer oil, the dry core often encloses the core and the winding with epoxy resin, and there is also a non-encapsulated type that is used nowadays. The winding is specially impregnated with special insulating paper. Insulating varnish, etc., to prevent the windings or core from getting wet. (Because the two are derived from different classifications due to different methods of process, use and structure, so we narrowly speaking)

In terms of production and dosage, the current dry-voltage level is only 35kV, and the capacity is relatively small compared to oil change, which is about 2500kVA. Since the dry-change manufacturing process is complicated with respect to the same voltage level and oil capacity of the same capacity. The cost is also high. So at present, it is still more oil in terms of dosage. However, due to the environmental protection of dry change, flame retardant, impact resistance and so on, it is often used in indoor and other high-demand power supply and distribution sites, such as hotels, office buildings, high-rise buildings and so on. If you are just a transformer user, it should be enough to understand these."

Each has its own advantages and disadvantages, low oil cost, easy maintenance, but flammable and explosive. Due to its good fire resistance, dry change can be installed in the center of the load to reduce voltage loss and power loss. However, the dry change is high in price, large in volume, poor in moisture and dust resistance, and high in noise.

The oil becomes gradually withdrawn, and the dry change can be dismantled and transported, cleaned, and easy to maintain.

It is better to distinguish from the outside;

The biggest difference between oil-immersed transformers and dry-type transformers is that there is no "oil". Because oil is liquid and has fluidity, oil-immersed transformers must have a casing. The inside of the casing is transformer oil, and the oil is immersed in the transformer. The coil does not see the coil of the transformer from the outside; the dry transformer has no oil, it does not need the outer casing, and can directly see the coil of the transformer; there is also a characteristic that the oil-immersed transformer has a oil pillow on it, and the internal storage Transformer oil, but now the new oil-immersed transformer also has transformers without oil pillows;

The oil-immersed transformer is convenient for heat dissipation, that is, it is convenient for the internal insulating oil to flow and dissipate heat. The heat sink is designed externally, just like the heat sink, but the dry type transformer does not have this heat sink, and the heat dissipation depends on the fan below the transformer coil. The fan is a bit like an indoor unit for home air conditioning;

Oil-immersed transformers are usually installed in a separate transformer room or outdoors due to the need for fire protection. Dry-type transformers are definitely installed indoors. Generally, they are installed in low-voltage power distribution rooms and installed side by side with low-voltage power distribution cabinets.




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