What Is a Transformer?

A transformer is a static machine that transfers AC power from one circuit to another at a constant frequency, but the voltage level can change, which means that the voltage can be increased or decreased as needed.

Its working principle is Faraday's law of electromagnetic induction, which states that "the magnitude of voltage is proportional to the rate of change of magnetic flux"

Necessity of transformer

Normally, electricity is produced at 11 kV. For economic reasons, AC power is transmitted at very high voltages, such as 220 kV or 440 kV over long distances. Therefore, the power station uses a step-up transformer.

Now for safety reasons, the step-down transformers of each substation reduce the voltage to different levels to supply power to different locations, thereby using the power at 400/230V.

Transformer structure

It mainly includes

Magnetic circuit (composed of the magnetic core, limbs, yoke, and damping structure).

Circuit (composed of the primary winding and secondary winding)

Dielectric circuit (composed of different forms of insulating materials, used in different places)

Tank and accessories (oil pillow, respirator, bushing, cooling pipe, etc.)

Transformer type

The various types are described below

1. The position of the winding relative to the core

Core type

Shell type

2. According to the winding ratio or turns

Step up

Step down

3. Service type

Power transformer

Distribution transformer

Instrument transformer

 Current Transformer

 Potential transformer

 Autotransformer

4. On the basis of the supply

Single-phase

Three-phase

5. On the basis of cooling

Air Natural (AN) or Self air-cooled or dry type

Air ForceD (AF) or Air Blast type

Oil Natural Air Natural (ONAN)

Oil Natural Air Forced (ONAF)

Oil Forced Air Forced (OFAF)

Oil Natural Water Forced (ONWF)

Oil Forced Water Forced (OFWF)