Analysis of Rectifier Transformer, Basic Parameters of Rectifier Transformer and Its Application

Rectifier transformer is the power transformer of rectifier equipment. Rectifier equipment is characterized by the original input current, and the vice-rectifier through the original output DC. Converter is the general term of three working modes: rectifier, counter current and frequency conversion. Rectifier is one of the most widely used modes. The transformer used as the power source of rectifier device is called rectifier transformer. Rectifier DC power supply for industrial use is mostly obtained by AC network through rectifier transformer and rectifier equipment. Because the rectifier winding current is non-sinusoidal and contains many high-order harmonics, in order to reduce the harmonic pollution to the power grid, in order to improve the power factor, it is necessary to increase the pulse wave number of rectifier equipment.

In the chemical industry with the most application of rectifier, high-power rectifier devices have low secondary voltage and high current, so they are similar to electric furnace transformer in many aspects, that is, the structure characteristic points mentioned above, rectifier transformer also has. The biggest characteristic of rectifier transformer is that the secondary current is not sinusoidal AC. Because of the unidirectional conduction characteristic of the following rectifier elements, each phase line is no longer at the same time with load current but with soft current conduction. The pulsating current in one direction is transformed into direct current through the filter device. The secondary voltage of rectifier transformer is not only related to the capacity connection group, such as the commonly used three-phase bridge rectifier circuit. The secondary voltage and current of the rectifier transformer with double inversion and balanced reactor are different for the same DC output voltage and current. Therefore, the parameter calculation of the rectifier transformer is based on the rectifier circuit, and the general parameter calculation is from the secondary side to the primary side.

Because the rectifier winding current is non-sinusoidal and contains many high-order harmonics, in order to reduce the harmonic pollution to the power grid, in order to improve the power factor, it is necessary to increase the pulse wave number of rectifier equipment, which can be solved by phase-shifting method. The purpose of phase shifting is to make a phase shift between the same terminal voltage of the secondary winding of rectifier transformer.

Performance and Structural Characteristics of Rectifier Transformer

Performance characteristics

(1) Electrical performance is stable: the product combines load characteristics, grid voltage fluctuation and atmospheric overvoltage, and determines reasonable and reliable insulation level and insulation model according to the load condition of rectifier transformer, so as to fully ensure the reliability and stability of electrical performance of the product. The environmental safety factor of the product is more than 1.67.

(2) High degree of dynamic stability: the product winding has high mechanical strength and strong anti-sudden ability to meet extremely harsh load environment. In the process of design and manufacture, the dynamic instability caused by transformer leakage or abnormal transportation can be eliminated. The product has high dynamic stability. High resistance, 30% higher than the same capacity of the power transformer impedance, to suppress di / dt, effective protection of rectifier components.

(3) Good thermal stability: advanced product design, strict control of the heating position and the hottest temperature rise of the product, and leave sufficient temperature rise margin. If necessary, axial oil pipeline can be added to the coil. According to the load loss value of the coil, cooling mode can be selected and oil flow can be reasonably distributed to achieve the best cooling effect. The main temperature rise index is at least 5 C lower than the national standard. Copper wire is used for coil and lead, and current density is low.

(4) Strong overload capacity: the product has strong overload capacity and overvoltage capacity, can operate safely under rated load for a long time, can operate safely under 110% overvoltage for a long time (ambient temperature 40 C); transformer and motor connected terminals can withstand 1.5 times rated current, lasting 5 S. Product design and manufacturing take full account of load characteristics, and meet overload requirements from temperature rise, insulation performance and accessories selection.

(5) Excellent performance indicators: no-load current design, manufacturing value is lower than the national standard value of S9 series transformers with the same capacity, which is based on the economy and reliability of full user use.

(6) The effect of saving electricity is obvious and the noise is low ("65dB").

(7) The structure is simplified and the shape is beautiful; the leakage of the tank can be prevented by adopting the anti-leakage design technology.

Structural characteristics

(1) Iron core: 30Q130 high permeability silicon steel sheet and 3-6 step-lap core stacking step-by-step multi-stage lamination are adopted to reduce the no-load loss, no-load current and noise.

(2) Winding: The electromagnetic wire adopts oxygen-free copper conductor with high conductivity, and the winding adopts the whole new technology of cylindrical, double-cake and new spiral structure, which makes the product structure more compact. The main insulation can be guaranteed effectively. The first and last layers are strengthened and the insulation performance is improved. The winding outer surface is wound with high strength compact tape, which improves the mechanical strength of the winding, and greatly improves the impact resistance and short circuit resistance of the product.

(3) Body: Insulation pads of the body are supported by high-strength laminated wood and laminated cardboard, so that the supporting area at the end of the winding reaches more than 95%, which further improves the short-circuit resistance of the product and the reliability of the product. The rigid buffer structure is used to connect the body with the cover of the box, which overcomes the phenomenon of "suspension" and "top cover" of the body. The insulating materials are all wrapped with high strength and high density cable paper, and the allowable pressure should be 45 Mpa.

(4) Fuel tank: Fuel tank adopts radiator tubing (double-row and three-row tubing adopts insertion mode), or uses stepped radiator, which increases heat dissipation capacity under the same area of tank wall; It can also be installed according to user's requirements, or uses corrugated oil tank, strong oil air-cooled or strong oil.