Transformers, step-up and step-down transformers (2023)

A transformer is an electrical device designed to convert alternating current from one voltage to another. It can be designed to increase or decrease voltages and works on the principle of magnetic induction. When an alternating current passes through the primary coil, a magnetic flux of alternating current is created in the iron core, inducing a voltage (or current) in the secondary coil. It consists of an iron core and a coil. The coil has two or more turns. The winding connected to the power supply is called the primary winding and the remaining windings are called the secondary winding.

How does an electrical transformer work?

The transformer mainly uses the principle of electromagnetic induction to work. The specific process is that when an AC voltage U1 is applied to the primary side of the electrical transformer and the current flowing through the primary winding is I1, the current creates an alternating magnetic flux in the iron core, causing the primary winding and the secondary winding to of electromagnetic connections.

(Video) Step-up & Step-down Transformer

Transformers, step-up and step-down transformers (1)

According to the principle of electromagnetic induction, electromotive force is induced when alternating magnetic flux flows through these two windings. Its size is proportional to the number of turns of the winding and the maximum value of the main magnetic flux. The voltage on the side with more turns is higher and the voltage on the side with fewer turns is lower. When the secondary of the transformer is open, that is, when the transformer is unloaded, the voltage at the primary and secondary terminals is proportional to the number of turns of the primary and secondary windings. That is, U1/U2 = N1/N2, but the primary and secondary frequencies are consistent to realize the voltage change. The operating principle of the transformer can be understood from the figure below.

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What types of step-down and step-down transformers are for sale on

isolation transformer

Transformers, step-up and step-down transformers (2)Isolation transformer refers to a transformer with galvanic isolation between the input winding and the output winding. It is widely used in electronic industry or industrial and mining enterprises, machine tools and mechanical equipment in general circuit control power supply, security lighting and power display. It can completely insulate the electrical part of the primary side and secondary side, and also insulate the electrical circuit. In addition, the high frequency loss of its iron core is used to prevent high frequency interference from entering the control circuit. To usean isolation transformerHanging the secondary on the floor can only be used in cases where the power supply reach is small and the line is short. At this point, the system capacitance current to ground is too small to cause personal injury. Another important role is the protection of personal safety! Can insulate people from dangerous voltages.

Ring core transformer

Transformers, step-up and step-down transformers (3)Toroidal transformer is a kind of step-down transformer power supply, which has the advantages of small volume, low noise, lower heat and high performance. In general, we use different voltages, e.g. B. 220V for home lighting, 36V for industrial security lighting, and the welding machine voltage needs to be adjusted. These cannot be separated from the toroidal transformer, which can step down the voltage we need using the principle of mutual electromagnetic inductance of the main and auxiliary coils. But how to improve the conversion efficiency ofRingkerntransformatorenit was a problem for many people. In fact, the conversion rate of a toroidal transformer is determined by the transformer's rating, the materials of manufacture and its location.

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control transformer

Transformers, step-up and step-down transformers (4)The control transformer is a small dry-type transformer primarily used to change the AC supply voltage. It is wound by an iron core and coil. It can not only change the AC current voltage, but also the impedance. If the design power is not exceeded, the current can also be changed. In different environments, the transformer also has different applications. It is generally used as control lighting and indicator light source for electrical equipment in machine tools and mechanical equipment. The multilevel control transformer can also be used in the chemical industry as a rectifier transformer. At this point it is only necessary to reconnect the adjustment taps of thecontrol transformer, cut off all device power supply, and then adjust the control transformer voltage with voltage regulator devices on both sides, so that it can be used in chemical industry.


Transformers, step-up and step-down transformers (5)Autotransformer is a transformer whose primary and secondary windings are on the same winding, the primary and secondary windings are directly connected in series, and the transformer is self-coupled. Common transformers transfer energy by electromagnetic coupling of primary and secondary coils and there is no direct electrical connection between primary and secondary coils, while autotransformers have direct electrical connection between primary and secondary coils and their low voltage coil is part of the voltage coil. high voltage. Autotransformers are also used as protective equipment for communication lines.

(Video) How does a Transformer work - Working Principle electrical engineering

Since the capacity calculated fromSpartransformatoris less than the rated capacity. Therefore, with the same rated power, the main dimensions of the autotransformer are smaller, and the effective material (silicon steel sheet and conductor) and construction material (steel) are reduced accordingly, thus reducing the cost. The reduction of effective materials leads to a corresponding reduction in copper and iron consumption, so that the efficiency of the autotransformer is higher. In addition, due to the reduction of main dimensions and mass, it is possible to manufacture transformers with higher capacities per unit under tolerable transport conditions.

What are the functions of a power transformer?

Ensuring electricity safety

There are many types of power transformers, but each type of transformer is a device that uses the principle of electromagnetic induction to change AC voltage. Therefore, the use of any transformer can ensure the safety of electricity. Changing the AC voltage without changing the power source can change the current, essentially allowing people to use electricity safely.

(Video) Transformers - working & applications (step up and step down) | A.C. | Physics | Khan Academy

Use the transformer to go up and down

The transformer can step up and down the voltage. We often use different voltages. For example, we need different voltages for domestic lighting and industrial security power. All this is inseparable from the transformer. With the transformer, we can reduce the voltage to the required voltage by the principle of mutual electromagnetic inductance and reduce the voltage loss.

impedance matching voltage

This feature is most commonly used in electronic circuits. Generally, electronics factories use impedance matching transformers to make the signal flow smoothly. Therefore, companies that need different voltages in the same environment can produce multi-winding transformers to meet the daily needs of workers.

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Something must be known before operating the transformer

Before using the step-up or step-down transformer, it must be fully tested to ensure its safe and stable operation. Transformer detection before operation mainly includes the following points.

  • According to actual production requirements for transformers and relevant national standards for transformer operation, DC resistance and insulation resistance of transformers are tested.
  • They should be tested if they are within the specified range.
  • Safe operation of the transformer has clear grounding requirements, so the grounding resistance and neutral grounding must be tested on the low voltage side. In addition, standardization of chassis grounding must be ensured. Make sure these ground points are correct and ensure ground stability.
  • Make sure that the explosion-proof respirators and hoses meet the prescribed requirements, and check that the dampening solution and explosion-proof film can be used properly.
  • Check all transformer wiring connections and ensure wiring is tight and phased correctly.
  • Check the performance of each sealing device to ensure a good seal, especially the vent valve, casing tube and oil cap to prevent leakage due to improper sealing.
  • Check that the oil level in the conservator corresponds to the operating environment.


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