What is the role of transformer on load switch? The role and classification of switching power suppl

The difference between the on-load voltage regulating transformer and the non-load voltage regulating transformer is that the former is equipped with a load voltage regulating device, which can withstand the load, and the latter can only change the position of the split head and adjust the voltage in the case of a power failure. The on-load voltage regulating transformer is used in places with strict voltage quality requirements, and is equipped with an automatic voltage regulation detection and control part to automatically adjust the voltage when the voltage exceeds the specified range.

Its main advantages are: it can adjust the voltage with load within the rated capacity range, and the adjustment range is large, the voltage fluctuation can be reduced or avoided, and the bus voltage quality is high, but its volume is large, the structure is complex, the cost is high, and the maintenance requirements are high. The no-load voltage regulating transformer (such as dry-type transformer, distribution transformer) must be powered off when changing the tap position, and the adjustment amplitude is small (for every change of one tap, its voltage adjustment or 5), the output voltage quality is poor, but it is relatively cheap and small.

The basic principle of on-load voltage regulation is that when the winding of the transformer is small, a number of tap taps are drawn, and through the on-load voltage regulation tap changer, under the condition of ensuring that the load current is not cut off, it is switched from one tap to another, so as to achieve the purpose of changing the effective turns of the winding, that is, changing the transformer transformation ratio.

On-load voltage regulation of the regulating transformer is not allowed under the following conditions:

1) When the transformer is overloaded (except for special circumstances);

2) When the light gas action of the on-load pressure regulating device is alarmed;

3) When the oil pressure resistance of the on-load pressure regulating device is unqualified or there is no oil in the oil standard;

4) When the number of pressure regulation exceeds the specified number;

5) When there is an abnormality in the pressure regulating device.

In layman's terms, it is possible to adjust the voltage with load and adjust the winding tap by relying on the switch. No load needs to be cut off to adjust the load, otherwise it is easy to damage the switch. General adjustment cannot be operated frequently.

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Reading guide] Before we introduce the switching power transformer, we must first understand the concept of power transformer. Because the former is actually a device that adds a switch tube to the power transformer, its original use has not changed. However, the function of this new type of transformer is very different from that of ordinary transformers.

In general, in the circuit, this kind of transformer not only has the actual function of ordinary transformer conversion voltage, but also has the functions of insulation isolation and corresponding power transmission. This type of transformer is generally used in the switching power supply of various high-frequency circuits. So what is the specific role of this product?

What is its classification? Let me introduce it to you.

For transformers, it is actually a device that can convert voltage. Usually we also call it a power transformer. However, the switching power supply transformer is different from other transformers in that it has one more switch than ordinary transformers.

In this way, a self-excited intermittent oscillator is formed, and its function is to adjust the input DC voltage into a high-frequency pulse voltage and then output.

In addition to the above functions, this product has a more important role, that is, the transfer and conversion of energy. Generally, in flyback circuits, when we turn on the switch, the corresponding transformer will convert the electrical energy into a magnetic field and store it. When we disconnect the switch, the magnetic field is converted into electrical energy.

So how does it work in a forward circuit? First of all, when we turn on the switch, the relevant input voltage is used to supply the load directly, and at the same time, the energy is stored by the inductor. Once we disconnect the switch, the energy will be transferred to the load through the energy storage inductor.

Finally, the switching power transformer can also convert the DC voltage transmitted to it, so that it can output various sizes of low voltage. We've talked about its role, so what is its classification?

Generally speaking, there can be two different types of switching power supply transformers, they are single-excitation and double-excitation. The two classifications have different structures and work very differently. The single-excitation type can input unipolar pulses, and can also output forward and reverse voltages; The difference between bipolar and slag high is the input bipolar pulse, and most of them are output bipolar pulse voltages.

Through the above text, many friends have a certain understanding of transformers. For switching power supply transformers, it is not only the difference of adding a power switch, but also some of his applications are more extensive. In addition, for some specific applications, the power transformer with this device can convert the voltage as needed, achieving the effect of meeting the needs of multiple types of voltage in the industrial field.

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A similar transformer is actually a transformer composed of two or more independent, similar coils, which are very similar in electrical properties, mechanical structure and appearance. Similar transformers are mainly used in occasions that require multiple outputs, such as audio and televisions. Similar transformers can be equipped with switches, that is, switches are set at the input or output of the transformer to facilitate the user to control the switching of the output voltage and the switching of the output port.

The design of similar transformer with switch can improve the flexibility and convenience of the transformer, so that users can switch the output voltage and output port at any time according to their needs, which is convenient and practical, but it should be noted that it is necessary to avoid overload and short block false start in the process of use, so as not to cause damage to the equipment or safety accidents.

The switching transformer generally refers to the transformer used in the switching power supply, which works in the pulse state of tens to tens of kilohertz or even hundreds of kilohertz frequencies, and the iron core is generally made of ferrite material.

The single-excitation transformer switching power supply is equivalent to the circuit shown in the figure, in which we regard the DC input voltage as a series of DC pulse voltage, that is, the unipolar pulse voltage, which directly supplies power to the switching transformer. Here we call the transformer a switching transformer to indicate that the circuit shown in the diagram is different from the general power transformer circuit in terms of working principle.

In the general power transformer circuit, when the input voltage at both ends of the power transformer is 0, it means that the input terminal is short-circuited, because the internal resistance of the power supply can be regarded as 0; In a switching transformer circuit, when the input voltage at both ends of the switching transformer is 0, it means that the input terminal is open, because the internal resistance of the power supply can be regarded as infinity.

The working principle, operation and maintenance of 10kV oil-immersed transformer 1. The structure of the transformer The main components of the oil-immersed transformer are as follows: 1. Iron core. The core is the main magnetic circuit part of the transformer, which is usually composed of hot-rolled or cold-rolled silicon steel sheets with high silicon content, thickness or and insulating paint on the surface.

2. Winding. The winding is the circuit part of the transformer, which is wound with paper-wrapped insulated flat wire or round wire. 3. a fuel tank.

4. Transformer protection device: mainly including oil conservator, dehydrating breather, safety air duct, gas relay, oil purifier, thermometer, etc. 5. an outlet casing.

Answer: "Switching transformer" generally refers to the transformer used in the "switching power supply", which works in a pulse state of more than ten to tens of kilohertz or even hundreds of kilohertz frequency, and the iron core is generally made of ferrite material. In addition to the voltage conversion function of ordinary transformer, it also has the functions of insulation isolation and power transmission, which is generally used in switching power supply and other occasions involving high-frequency circuits.

Function: The switching power supply transformer and the switch tube together form a self-excited (or other-excited) intermittent oscillator, so as to adjust the input DC voltage into a high-frequency pulse voltage.

It plays a role in energy transfer and conversion. In flyback circuits, when the switch is turned on, the transformer converts the electrical energy into magnetic field energy and stores it, and releases it when the switch is cut off. In a forward circuit, when the switch is turned on, the input voltage is supplied directly to the load and the energy is stored in the energy storage inductor.

When the switch is cut off, the energy storage inductor is transferred to the load for freewheeling.

The input DC voltage is converted into the required low voltage.

All transformers work on the same principle, whether they are high or low frequencies.

The changing current in the primary coil produces a varying magnetic flux in the core, which then generates an induced electromotive force in the secondary stage.

Compared with traditional power supplies, switching power supplies have the characteristics of low power consumption, high efficiency, small size, light weight, wide voltage stabilization range, etc., and are widely used in computers and peripheral equipment, communications, automatic control, household appliances and other fields.

However, the outstanding disadvantage of switching power supply is that it produces strong electromagnetic interference, and the interference signal has a wide frequency range and a certain amplitude, and it will pollute the electromagnetic environment through conduction and radiation, and cause interference to communication equipment and electronic products. If not handled properly, the switching power supply itself can become a source of interference.

The disadvantage of traditional transformer power supply is that it is heavy in size and low in efficiency, but at present, in order to pursue profits, manufacturers in the market use inferior selenium steel sheets or fake ones, resulting in overheating of transformers and lower efficiency.

Switching power supply: high conversion efficiency, wide input voltage, low output ripple, its weight can be made very light, the cost is high, the disadvantage is that the working frequency is higher, the radiation is larger, and the power response is not as good as the transformer power supply.

Transformer power supply: It is the same as the switching power supply, and it is the same.

They are all power converters, the switching power supply is an electronic converter, and the transformer is an iron core type.

The power frequency transformer is the conversion (buck-boost) of alternating current, and the high-frequency transformer is only a component of the switching power supply.

First of all, the switching power supply is DC---DC, and the transformer is AC --- AC; Secondly, the switching power supply works at a higher frequency (generally in tens of kilohertz), and the transformer has high frequency, there are also low frequency, the pulse transformer used in the switching power supply is the high-frequency transformer, the iron core is a ferrite and other magnetic cores, its size is small, the efficiency is high (the higher the frequency, the higher the efficiency), the transformer everyone first thinks of the power frequency transformer, its working frequency of 50 Hz, it belongs to the low-frequency transformer, and the core must be superimposed with silicon steel sheets of soft magnetic materials (to prevent eddy current from producing Joule heating); Again: the functional scope of the two is not the same, the switching power supply includes a pulse transformer, but also contains the upper and lower end of the rectifier part, and no matter which frequency range of the transformer is only transformer, there is no rectification function;

Let's talk about the case, let's talk about the power circuit of the TV! The power supply part of the color TV is a typical switching power supply; In the past, the power supply circuit of black and white TV was composed of a power frequency transformer and a rectifier filter and voltage stabilization circuit. The color TV power supply is to directly rectify the 220V alternating current into a direct current of about 300V, and then cut it into a high-frequency pulse by the switching triode, and then step down the voltage through the pulse core transformer, and then rectify the filter output low-voltage DC (its whole process also solves the problem of voltage stabilization); The sum of these processes is worth a switching power supply.

And the power frequency transformer in the black and white TV brother represents the transformer you are talking about, it does not contain a rectifier filter circuit. Therefore, the functional scope of the two is different.

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"Electronic transformer" can be simply understood as "simple switching power supply without voltage regulation".

It is mainly used in some occasions that require high-power transformers and do not have strict requirements for frequency, output voltage and other parameters, but are sensitive to cost requirements, such as spotlight transformers in lighting applications. Spotlights are pure resistive loads, which are not sensitive to the working frequency, but require a lot of power, so the use of traditional power frequency transformers is costly and wastes copper and iron, so it is most suitable to use "electronic transformers" to solve this need.

The "switching power supply" can control the output power to accurately adjust the output voltage by PWM technology, and the output voltage can be guaranteed to remain unchanged when the input voltage changes, while the "electronic transformer" does not have this function!

Compared with the traditional linear regulated power supply, the switching power supply has many advantages, high parameters (cost, efficiency, load regulation), so it has a wide range of applications, such as the PC power supply used in the computer, TV, mobile phone charger, is "switching power supply".

The working principle of electronic transformers is similar to that of switching power supplies;

All of them convert high-voltage electricity into low-voltage electricity through electronic components;

The difference is: the electronic transformer converts high-voltage power frequency electricity into low-voltage and high-frequency electricity, and is used in lighting applications that only need to be transformed;

The switching power supply can output a stable DC voltage according to the design.