变压器基本知识英文.docx

1、变压器基本知识英文CONTENTSSection One Basic Knowledge of transformerSection Two Basic Work Principle of TransformerSection Three Operation of Transformer in ParallelSection Four Operation and Maintenance of TransformerSection Five Abnormal Operation and Remedies of TransformerSection Six Operation and Mainte

2、nance of Load Tap SwitchSection One Basic Knowledge of TransformerI. Use of TransformerThe transformer is a static electric device which can transform alternative voltage and current to transfer electric power in same frequency between two or more windings by means of electromagnetic induction.The t

3、ransformer has a lot of uses. There are various kinds of transformers widely used in all departments of national economy. In view of the angle from the electric power system, an electric power network connects many power plants and users and the electric energy generated from the electric power netw

4、ork shall be always sent to user areas by transmission in long distance. In case the electric power to be transferred is constant, the higher the transferred voltage, the less the current to be needed because the voltage drop is in direct proportion with the current and the loss of electric energy i

5、s in direct proportion with the square of the current. Therefore it can largely reduce the voltage drop and energy loss of the transmission lines if higher transferred voltage is adopted. At present it is difficult technically to make the generator with higher voltage, alternatively, the step-up tra

6、nsformer is used to rise up the voltage at the terminal of the generator before the electric power is sent. The longer the transmission distance, the larger the transferred power and the higher the requirement of volume and voltage levels of the transformer. As there are a lot of levels of voltage e

7、xisted in the power network, it should have transformers with different sizes of voltage to make connection.On the other hand, when electric energy is transferred to the receiving terminal it should have the step-down transformer to reduce the high voltage on the transmission lines to the voltage of

8、 the power distribution system, then reduce the voltage to that required by all electric equipments through the distribution transformer.It can be seen the position of the transformer in the electric power system is vital important. Not only it requires much transformers, normally the total installa

9、tion capacity of transformers are 8-10 times of that of the generator, but also it requires that transformers should have good performances, safe and reliable operation.Except in the electric power system, the transformer is also used in industries and mines where special power supply is needed, for

10、 example the transformer for the electric furnace in metallurgy, the transformer for the rectification in electrolysis or chemical industry, the transformer for electric welding, the transformer for test, the transformer for traction in railway and those products belonging to the category of the tra

11、nsformer such as mutual inductor, reactor, extinction coil etc. As they have similar basic principle and structure of the transformer and much application and varieties, they are called transformer-like products.II. Classification of Transformer(1) Classify according to use, there are power transfor

12、mer, electric furnace transformer, rectification transformer, electric welding transformer, test transformer, voltage-regulating transformer, reactor and mutual inductor etc.(2) Classify according to number of output phase, there are single-phase transformer, three-phase transformer.(3) Classify acc

13、ording to cooling media, there are dry transformer, oil-immersed transformer and air transformer.(4) Classify according to cooling style, there are oil-immersed self-cooled transformer, oil-immersed air-cooled transformer, oil-immersed and forced oil circulation air-cooled transformer, oil-immersed

14、and forced oil circulation water-cooled transformer and dry transformer.(5) Classify according to number of winding, there are double-winding transformer, three-winding transformer and autotransformer.(6) Classify according to style of voltage-regulating, there are field-free voltage-regulating tran

15、sformer and load voltage-regulating transformer.(7) Classify according to structure of iron core, there are core-type transformer and shell-type transformer.(8) Classify according to insulation level of the neutral point, there are full insulation transformer and tap insulation transformer.(9) Class

16、ify according to material, there are copper wire transformer and aluminum wire transformer.III. Model and Rated Data of Transformer1. Model of TransformerThe various kinds of classification of the transformer cannot cover all characteristics of the transformer. It should have the model of product to

17、 express all it characteristic. The model of the transformer consists of the Chinese phonetic alphabets and Arabic numerals and each alphabet or digit stands for a certain meaning.S F S R N Z - / Voltage level of high voltage winding（kV） Rated capacity (kVA) Voltageregulating style: it means load vo

18、ltage-regulating if it appears otherwise it means field-free voltage-regulating “Resisting” high temperature (it means class F insulation temperature Insulation (cooling) media is hard “burning” oil Number of windings: it means three windings if it appears otherwise it means double windingsCooling s

19、tyle: it means air-cooling if it appears otherwise it means self cooling Three-phase transformerExample of the model of the electric power transformer product:SRNZ-25000/33 means three-phase load voltage-regulating high temperature resisting liquid-immersed self-cooled double-winding power transform

20、er with the rated high voltage of 33kV and the rated capacity of 25000kVA. 2. Rated Data of the Transformer(1) The rated voltage U1N /U2N with the unit of kilovolt (kV). For the three-phase transformer the rated voltage means the linear voltage.(2) The rated current I1N /I2N with the unit of ampere

21、(A). For the three-phase transformer the rated current means the linear current.(3) The rated capacity SN, i.e. the apparent power with the unit of kilovolt-ampere (kVA). It has relations with the rated voltage and the rated current as follows:The single-phase transformer SN = U1N I1N ; SN = U2N I2N

22、The three-phase transformer SN = U1N I1N ; SN = U2N I2NThe rated capacity of the transformer is the guaranteed value of the output capacity of the transformer. It is different with the rated capacity of the winding. The rated capacity of the double-winding transformer is the rated capacity of the wi

23、nding while for the multiple windings transformer, the rated capacity of each winding should be specified and its rated capacity is the rated capacity of the maximum winding.In our country the level of the rated capacity of the transformer is R10 preferred numbers increased by the times of , only th

24、at of 30kVA and those of 63000kVA and upwards are different with preferred numbers. The levels of detailed capacities are shown in Table 1-3.Table 1-3 Levels of Rated Capacities of Transformer Unit: kVA1020(30)506380100125160200250315400500630800100012501600200025003150400050006300800010000125001600

25、0200002500031500400005000063000(90000)(120000)(150000)(180000)(240000)(360000)Note: The single-phase transformer to be consisted in the three-phase transformer set has only 1/3 of the values in the table while the single-phase transformer for other use has the same values in the table.(4) The rated

26、frequency f with the unit of Hertz (Hz). In our country the main frequency is 50 Hz.(5) The unload current and unload loss. When the secondary winding of the transformer is open and the primary winding is applied by the rated voltage with the rated frequency of sinusoidal wave, the current passing t

27、hrough it is called as the unload current I0. Normally the unload current is expressed by the percentage of the rated current. The active power generated when the transformer is operated under no-load is called as unload loss P0.(6) Reactance voltage and load loss. When the secondary winding of the

28、transformer is in short circuit, the voltage applied upon the primary winding to generate the rated current to flow through is called as the reactance voltage Uk. Normally the reactance voltage is expressed by the percentage of the rated voltage. The caused loss corresponding to the rated capacity u

29、nder the reference temperature is called as the load loss Pk.In addition, the nameplate of the transformer also shows number of phases, wiring diagram and groups to be connected, operation style and cooling style, total weight of the transformer, total weight of oil etc.Section Two Basic Work Princi

30、ple of TransformerI. Basic Electromagnetic Law1. Law of Electromagnetic InductionSuppose a coil of N turns in the magnetic field, in case the magnetic flux intercrossed with the coil changes, theinduced electromotive force shall be generated in the coil. If the supposed direction of theinduced elect

31、romotive force and the positive direction of intercrossed magnetic flux are in accordance with the right-hand screw rule, then the induced electromotive force is: （2-1）in which e theinduced electromotive force, V;N number of turns of the coil; d change of the magnetic flux in the coil, Wb; dt time r

32、equired by the change of magnetic lines of flux, s.2. Magnetic Induction Intensity (magnetic flux density)The magnetic induction intensity means the number of magnetic lines of flux passing through the vertical unit area. It is used to judge if number of the magnetic lines of flux is strong or not. The calculation formula is shown as follows: （2-2）In which, B magnetic induction intens