(1) According to the purpose

1. Power transformer, used for step-up or step-down of power system.

2. Test the transformer to generate high voltage, and conduct high voltage test for electrical equipment.

3. Instrument transformers, such as voltage transformers and current transformers, are used for measuring instruments and relay protection devices.

4. Special purpose transformers, electric furnace transformers for smelting, rectifier transformers for electrolysis, welding transformers for welding, voltage regulating transformers for testing, etc.

(2) According to the number of phases

1. Single-phase transformers are used for single-phase loads and three-phase transformer groups.

2. Three-phase transformer, used for step-up and step-down of three-phase system.

(3) According to the winding form

1. Autotransformers are used to connect ultra-high voltage and large-capacity power systems.

2. Double-winding transformers, used to connect power systems of two voltage levels.

3. Three-winding transformers are used to connect power systems of three voltage levels, and are generally used in regional substations of power systems.

(4) According to the form of iron core

1. Core-type transformers, used in high-voltage power systems.

2. Shell-type transformers, special transformers for high current, such as electric furnace transformers and welding transformers, etc.; or power transformers for electronic instruments, TVs, radios, etc. The shell structure can also be used for large capacity power transformers.

(5) According to the cooling medium

1. Oil-immersed transformers, such as oil-immersed self-cooling, oil-immersed air-cooled, oil-immersed water-cooled, forced oil-circulating air-cooled and water-cooled, etc.

2. Dry-type transformers rely on air convection for cooling. Such low-voltage, oil-free transformers are usually cooled by fans and are suitable for fire protection and other occasions. For the low-voltage transformers used in the factory building of the 600MW unit, dry-type transformers are generally used for fire protection requirements.

3. Gas-filled transformers use special gas (SF6) instead of transformer oil to dissipate heat.

4. Evaporative cooling transformer, use special liquid instead of transformer oil for insulation and heat dissipation.

Transformer types and characteristics

Post time: Jan-20-2022