What is a transformer? Types of transformers. Principle of operation of the transformer

In this article, we consider what a transformer is. Types of transformers will be described, the principle of action and design, too, will not be left without attention. It should be noted that this is a kind of static (fixed) AC machines that are used for various purposes not only in everyday life, but also in industry. For example, to account for consumed electricity. But first things first.

What is this device?

It is an electric static machine that is used to convert current or voltage. And we can distinguish several types of devices, depending on which network is powered. So, three-phase ones have three network windings, which are switched on according to the "star" or "triangle" scheme. In this it is possible to draw an analogy with asynchronous electric motors. There are various types of power transformers, which will be described below.

But in everyday life, devices are used in which there is one network winding. In addition, there is at least one secondary, which serves to power devices. For example, in tube technology, power transformers are used , with several secondary windings. There was a need to obtain several voltage values from one device: 6.3 V, 250 V. In addition, in life, one can find current transformers. They are installed in electric meters and serve for the operation of the monitoring device.

Design

The basis of the transformer is difficult to isolate, but if we rely on weight, then this is undoubtedly the core (magnetic core). It is made of steel sheets, which are assembled together and tightly tied together. This makes it possible to obtain the maximum possible cross-section of the magnetic circuit. But not only steel can be used, cores made of ferromagnets are often made. This substance, which is very similar in properties to metal, but has a slightly different structure. There are certain types of transformers, photo of the basic constructions are given in the article.

At least two windings are present in the design. One (primary) supply voltage. With the second, third, N-th, reduced voltage with a frequency and shape, similar to the input voltage. Power windings consist of a copper wire. It is wound on a frame located around the magnetic circuit. When voltage is applied to the primary circuit, an alternating magnetic field appears , which in the secondary winding induces EMF. As a result, a certain potential difference appears at the output.

Power Transformers

These types include those that convert electricity to the grid. This is not only a transformer installed at the substations. Types of power transformers are diverse, they serve not only to reduce the voltage from 110 kV, for example, up to 6 kV, in the case of a substation. These include devices used in power supply units for household radio equipment. In fact, the design of all the same, there are common nodes.

Even welding transformers, whose kinds are diverse, have a similar structure. Here only there are small nuances, for example, power machines in substations are equipped with an oil cooling system, while welding work without it. But the latter has an adjustment of the output current. This is necessary for welding different thicknesses of metals. Well, the devices used in everyday life, and do not have such adjustments.

Autotransformers

The autotransformer is one of the types in which the primary and secondary windings are directly connected. This allows you to get not only an electrical connection in the device, but also an electromagnetic one. Normally, the autotransformer has three outputs, and this allows you to obtain different voltage values. A distinctive feature of autotransformers is a high coefficient of efficiency. But there is one significant drawback - the primary and secondary circuits are not electrically isolated from each other. It is used for the most part to regulate the power of the consumer such a transformer. Types of transformers for other purposes are discussed below.

Measuring

For the use in AC electrical installations a special type of transformer is created - a measuring type. Thanks to them, the limits of measuring devices are increased. In addition, they allow measuring the current flowing through it without electrical connection to the power cable. In other words, without galvanic coupling, it is possible to monitor the flowing current in the circuit. But we can distinguish two types of measuring devices - voltage and current transformers. There are different types of current transformers, their difference in size and application.

Current transformers allow conversion. In this case, the large current flowing in the circuit decreases to a safe value. Moreover, it is safe at the output for control or measuring systems, alarm and protection devices. The primary winding is a section of the conductor, a secondary wound around it. With the latter, a current of 1 or 5 amperes is removed. But the voltage transformers are designed for a different purpose. They produce a voltage drop to measure the characteristics. With their help galvanic isolation of protective devices from the circuit with high voltage is carried out.

Pulse

This type of device is used for highly specialized purposes. It is necessary to convert a series of pulse signals. And the duration of one pulse can reach several tens of microseconds. And there is one small feature - only the amplitude of the signal changes, but not its shape. By the way, there are certain types of transformer protection , the pulsed ones are also supplied with circuits preventing the excess of voltage or current.

As a rule, pulse devices are used in circuits in which a signal of a rectangular shape is flowing. Often, this type of device is used in television technology. They convert small in duration video signal pulses with a very high duty cycle. And at the output you get a signal in its original form, but with an increased amplitude.

Conclusion

Now you know what a transformer is. We examined the types of transformers and saw that they all have slight differences, despite the fact that the design is largely similar. Please note that when working with any electrical devices, observe the safety precautions. In addition, to maintain the AC mains, you must have a tolerance group.