Talking about the Types and Characteristics of Common Transformers

There are many kinds of transformers, but as far as their working principle is concerned, they are all made according to the principle of electromagnetic induction. Generally, the common transformers can be classified as follows.

I. Distribution by Purpose

1. Power transformer, used for boost or buck of power system.

2. Test transformer to produce high voltage, and carry out 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. Transformers for special purposes, furnace transformers for smelting, rectifier transformers for electrolysis, welding transformers for welding, voltage regulating transformers for testing, etc.

2. Dividing by phases

1. Single-phase voltage transformer for single-phase load and three-phase transformer group.

2. Three-phase transformer, used for three-phase system boost and buck.

3. According to winding form

1. Autotransformer, which is used to connect ultra-high voltage and large capacity power system.

2. Double-winding transformer, which is used to connect two voltage levels of power system.

3. Three-winding transformer, which is used to connect three voltage levels of power system, is generally used in regional substations of power system.

IV. According to the form of iron core

1. Core transformer for high voltage power system.

2. Shell transformer, used for special transformers with large current, such as electric furnace transformer and welding transformer, or for power transformers such as electronic instruments, television, radio, etc. Shell structure can also be used in large capacity power transformer.

V. According to Cooling Medium

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

2. Dry-type transformers rely on air convection for cooling. This kind of transformer with low voltage and no oil is usually cooled by fan, which is suitable for fire protection and other occasions. Dry-type transformer is widely used in factory low-voltage transformer of 600 MW unit for fire protection.

3. Inflatable transformer uses special gas (SF6) instead of transformer oil for heat dissipation.

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

6. Power Transformer Running Regulations DL/T 572-1995 divides transformers into three categories according to capacity

1. Distribution transformer, voltage 35 kV and below, three-phase rated capacity 2500 kVA and below, single-phase rated capacity 83 kVA and below, with independent windings, natural circulation cooling transformer.

2. Transformers with intermediate distribution, three-phase rated capacity not exceeding 100 MVA or each column capacity not exceeding 33.3 MVA, have independent windings, and rated short-circuit impedance Z meets the requirements.

3. Large transformer, three-phase rated capacity of more than 100 MVA, or its rated short-circuit impedance Z meet the requirements.