Types and differences of power dry-type transformers

How to distinguish transformers

1. Divided by phase number:

1.1 Single phase oil immersed transformer: used for single-phase loads and three-phase transformer groups.

1.2 Three phase transformer: used for voltage rise and fall in three-phase systems.

2. Classified by cooling method:

2.1 Dry type transformer: It relies on air convection for cooling and is generally used for small capacity transformers such as local lighting and electronic circuits.

2.2 Power Transformer: Relying on oil as the cooling medium, such as oil immersed self cooling, oil immersed air cooling, oil immersed water cooling, forced oil circulation, etc.

3. Classified by purpose:

3.1 Voltage Transformer: Used for voltage rise and fall of current transformers.

3.2 Instrument transformers: such as low-voltage distribution cabinets, low-voltage distribution, instruments used in distribution systems, and relay protection devices.

3.3 Test Transformer: A transformer capable of generating high voltage and conducting high voltage tests on indoor equipment. 4) Special transformers: such as electric furnace transformers, rectifier transformers, adjustment transformers, etc.

4. Classified by winding form:

4.1 Dual winding transformer: used to connect two voltage levels in the power system.

4.2 Three winding transformer: generally used in power system regional substations, connecting three voltage levels.

4.3 Autotransformer: used to connect power systems with different voltages. It can also be used as a regular step-up or step-down transformer.

5. Classified by iron core form:

5.1 Core Transformer: Used for high-voltage power transformers.

5.2 Shell type transformer: used for special transformers with high currents, such as furnace transformers and welding transformers; The biggest difference between oil immersed test transformers and dry-type transformers is the presence or absence of "oil". However, since oil is liquid and has fluidity, oil immersed test transformers must have a casing. The inside of the casing is transformer oil, and the transformer coils are soaked in the oil, which cannot be seen from the outside; And dry type transformers do not have oil, so there is no need for an outer shell, and the coils of the transformer can be directly seen; Another characteristic is that oil immersed transformers have an oil conservator on top and store transformer oil inside. However, new oil immersed test transformers also have transformers produced without an oil conservator; The oil immersed test transformer is designed with a heat sink on the outside for the convenience of heat dissipation, that is, for the flow and heat dissipation of internal insulation oil. It is similar to a heat sink, but the dry-type transformer does not have this heat sink. The heat dissipation relies on the transformer under the transformer coil, which is similar to the electrical of a household fan; Oil immersed transformers are generally installed indoors or outdoors in separate transformer rooms due to fire protection needs, while dry-type transformers are definitely installed indoors. Generally, they are installed in measurement rooms and installed side by side with air conditioning.

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