What is the difference between rectifier transformers and power transformers?

Firstly, let’s understand these two different terms:

What is a rectifier transformer

Current conversion refers to the three working modes of rectification, reverse current, and frequency conversion, among which rectification is widely used. The characteristic of rectification equipment is that the input AC power is rectified and filtered to output DC power. A rectifier transformer is a power transformer used in rectifier equipment. Most industrial rectified DC power sources are obtained from rectifier transformers and rectifier equipment.

Most casting companies use rectifier transformers

What is a power transformer

A power transformer is usually a transformer that supplies power to an electric drive system. Most transformers in the power grid are power transformers.

The difference between rectifier transformer and power transformer

(1) Functional differences

The function of a rectifier transformer is to provide appropriate voltage for the rectifier system; 2. Reduce the pollution of the power grid caused by waveform distortion caused by rectification systems.

The output of the rectifier transformer is still AC and only supplies power to the rectifier equipment. Usually, the primary side is connected in a star shape and the secondary side is connected in an angle shape to suppress high-order harmonics. The neutral point of the secondary side corner is not grounded. When the rectification equipment is grounded at one point, it will not cause equipment damage, and the grounding fault alarm signal is sent through the grounding detection equipment. 1. Add shielding isolation between secondary coils.

Rectifying transformers are mainly used in fields such as electrolysis, smelting, excitation, power transmission, cascade speed regulation, electrostatic precipitator, and high-frequency welding. There is a slight difference in structure. In order to smooth the waveform, some electrolytic rectifier transformers are made into six phase outputs and six phase rectifier bridges are added externally to obtain relatively smooth waveforms. Based on the current waveform characteristics and anti harmonic requirements of thyristor rectifier circuits used in smelting and high-frequency welding, the eddy current losses in the windings of rectifier transformers and the stray losses in structural components were optimized for certain data and processes. In fact, the overall structure is also similar.

Power transformers are usually grounded at the neutral point of the y/y connection (providing single-phase power). If used for rectification equipment, it will damage the rectification equipment in the event of a ground fault, and its ability to suppress high-order harmonics generated by the rectification equipment is also poor.

(2) Different uses

The transformer used as a rectifier power source is called a rectifier transformer. Most rectified DC power sources used in industry are obtained from the AC power grid through rectification equipment consisting of rectifier transformers and rectifiers. In today’s highly modernized society, its enormous use can be directly or indirectly seen in almost every field. Power transformers are mainly used for power systems, daily lighting, and factory electricity. The main uses of rectifier transformers are as follows:

1. Electrochemical industry;

2. Traction DC power supply;

3. DC power supply used for transmission;

4. DC power supply for DC transmission;

5. DC power supply used for electroplating or electrical processing;

6. DC power supply for excitation;

7. DC power supply for charging;

8. DC power supply for electrostatic precipitator;

3. Output voltage difference

(1) Address difference

Due to its close integration with the rectifier, the output voltage of the rectifier transformer is called the valve side voltage, which is named after the unidirectional conductivity of the diode.

(2) Differences in Calculation Methods

Due to the different waveforms of the rectifier load current, the calculation method for its output current is not only very different from that of power transformers, but also varies for different rectifier circuits.

4. There are differences in design and manufacturing

Due to the differences in usage, design, and manufacturing between rectifier transformers and power transformers: considering the working conditions of rectifier transformers, they achieve low current density and magnetic flux density, as well as slightly higher impedance. In terms of winding structure, the valve side sometimes requires two windings for forward and reverse transmission or forward transmission and reverse braking power supply. When braking, the inverter is in the working state of the inverter; If the transformer has harmonic requirements, a shielding layer with grounding terminals should be placed between the windings; Take various measures such as strengthening the pressure plate and bracket, expanding the oil circuit, etc. to improve the winding’s ability to resist short circuits; In addition, in terms of heat dissipation, the heat dissipation margin is usually larger than that considered in the design and manufacturing of power transformers.