How do transformers increase voltage and decrease current?

What is a dry type transformer?

Definition: Dry type transformer refers to the transformer whose iron core and winding are not impregnated in insulating oil. It uses the principle of magnetic induction and electromagnetic induction to transform the input voltage into the output voltage through the magnetic field coupling between the primary and secondary windings in a free air environment.

Structure: The dry type transformer is mainly composed of an iron core composed of silicon steel sheets and an epoxy resin cast coil. Insulation tubes are placed between the high and low coils to increase electrical insulation and the coils are supported and restrained by a pad. The fasteners of the overlapping parts have anti-loosening performance.

dry type transformer

Working principle of dry type transformer

A transformer is an electronic device that transfers alternating current from one circuit to another while changing the magnitude of voltage and current. A transformer consists of two or more coils that are coupled to each other by a magnetic material. One coil is called the "main coil", which is the power input. The other coil is called the "secondary coil", which is the power output.

When the current in the main coil changes (for example, there is an AC current input), the changing magnetic field passes through the secondary coil to induce the electromotive force in the secondary coil, which in turn drives the current change in the coil.

According to Faraday's law of electromagnetic induction, a change in the magnetic field will cause a change in the current within the coil. And according to Ohm's law, voltage and current are proportional to each other. So, when the voltage in the main coil changes, the voltage in the secondary coil will also change and the current will change with it.

dry type transformer

The reason why the current becomes smaller after the transformer boost

The main reason that the current decreases as the voltage in a transformer increases is that power is conserved ‌. When the transformer voltage is increased, because the power is unchanged, the current will decrease accordingly. Specifically, the power of the transformer is equal to the input voltage multiplied by the input current, that is, P=V×I. Therefore, when the voltage increases, the current must decrease, while the total amount of electric energy remains unchanged.

In addition, there are also losses in the actual transformer, which will cause the decrease of the secondary side current to be slightly smaller than the theoretical inverse relationship‌. In practical applications, the design and operating conditions of the transformer will also affect the change of current. For example, the load characteristics of the transformer, the resistance and reactance of the winding and other factors will have an effect on the change in current‌.

Advantages of smaller transformer current

After the transformer is boosted and the current becomes smaller, although it will reduce the transmission speed of the current, it helps to reduce the loss of energy. Because the resistance of the wire will lead to the loss of electrical energy, and the current reduction can reduce the resistance in the wire, which can further reduce the loss of electrical energy. Therefore, in the long distance transmission, the transformer boost can effectively reduce the loss of electric energy and improve the efficiency of power transmission.