Rectifier transformer and power transformer, what is the difference?

Converter is the general name of three working modes of rectification, countercurrent and frequency conversion, and rectification is one of the most widely used. The characteristic of the rectifier equipment is to output the input AC power to DC after the rectification filter. The rectifier transformer is the Power Transformer of the rectifier equipment. Most of the industrial rectifier DC power supply is obtained by means of rectifier transformer and rectifier equipment.

What is a power transformer

Power transformers generally refer to transformers that supply power to electric drive systems, and most transformers in the power grid are power transformers.

The difference between rectifier transformer and power transformer

First, function difference The function of the rectifier transformer:

1. Supply the appropriate voltage to the rectifier system;

2. It is to reduce the pollution of the power grid caused by waveform distortion caused by the rectification system.

The output of the rectifier transformer is still AC, it only provides power to the rectifier equipment. Usually, the next side connection is star shape and the second side connection is angular shape, which is used to suppress higher harmonics. The corner neutral point of the secondary side connection is not grounded. When the rectifier device is grounded at one point, the device will not be damaged. The ground fault alarm signal is sent through the ground detection device. There is a shielding isolation between the first and second times.

Rectifier transformer is mainly used in electrolysis, smelting, excitation, transmission, cascade speed regulation, electrostatic dust removal and high frequency welding and other fields. The structure has a little difference, in order to smooth the waveform with the rectifier transformer for electrolysis, some are made into six-phase output, and the six-phase rectifier bridge is added outside to get a relatively smooth waveform. Smelting and high-frequency welding according to the current waveform characteristics and anti-harmonic requirements of thyristor rectifier circuit, eddy current loss in rectifier transformer windings and stray loss in structural parts, for some data and process optimization, in fact, the general structure is similar.

The power transformer is usually grounded at the neutral point of the Y/Y connection (providing single-phase power supply). If it is used for rectifier equipment, it can cause damage to the rectifier equipment when a ground fault occurs. And its ability to suppress the high order harmonics produced by the rectifier equipment is also poor.

Second, the difference in use

A transformer used as a power source for a rectifier device is called a rectifier transformer. Most of the rectifier DC power used in industry is obtained by the rectifier equipment composed of rectifier transformers and rectifiers in the AC power network. In today's highly modernized world, its great use can be seen directly or indirectly in almost every field. Power transformers are mainly used in power systems and daily lighting and factory power.

The main uses of the rectifier transformer are as follows:

1, electrochemical industry;

2, traction DC power supply;

3. Dc power supply for transmission;

4, DC power supply with DC transmission;

5, DC power supply for electroplating or electrical processing;

6. Dc power supply for excitation;

7. Dc power supply for charging;

8. Dc power supply for electrostatic dust removal;

Three, the output voltage difference

1) Differences in address:

Due to the close combination with the rectifier, the output voltage of the rectifier transformer is called the valve side voltage. The name derives from the unidirectional conductivity of the diode.

2) Differences in calculation methods:

Due to the different waveforms of the load current of the rectifier device, the calculation method of the output current is not only very different from that of the power transformer, but also different from that of the rectifier circuit.

Fourth, there are differences in design and manufacturing

Due to the difference between the use of the rectifier transformer and the power transformer, the design and manufacturing are also very different from the power transformer: considering the working condition of the rectifier transformer, the rectifier transformer has a low selection of current density and magnetic flux density; Impedance is also achieved slightly larger. In terms of the structure of the winding, the valve side is sometimes required to have two windings, respectively providing positive and reverse transmission or forward transmission and reverse braking. When braking, the converter is in the inverter working state; If the transformer has harmonic requirements, a shielding layer with a ground terminal should be placed between the windings; The anti-short circuit ability of windings is improved by strengthening the pressure plate and stay and increasing the oil passage. In addition, in terms of heat dissipation, there is usually a greater margin than that considered in the design and manufacture of power transformers.