Transformer变压器外文文献翻译
负载运行的变压器中英文翻译
The Transformer on loadIt has been shown that a primary input voltage 1V can be transformed to any desired open-circuit secondary voltage 2E by a suitable choice of turn’s ratio. 2E is available for circulating a load current impedance. For the moment, a lagging power factor will be considered. The secondary current and the resulting ampere-turns 22N I will change the flux, tending to demagnetize the core, reduce m Φ and with it 1E . Because the primary leakage impedance drop is so low, a small alteration to 1E will cause an appreciable increase of primary current from 0I to a new value of 1I equal to ()()i jX R E V ++111/. The extra primary current and ampere-turns nearly cancel the whole of the secondary ampere-turns. This being so, the mutual flux suffers only a slight modification and requires practically the same net ampere-turns 10N I as on no load. The total primary ampere-turns are increased by an amount 22N I necessary to neutralize the same amount of secondary ampere-turns. In the vector equation,102211N I N I N I =+; alternatively, 221011N I N I N I -=. At full load, the current 0I is only about 5% of the full-load current and so 1I is nearly equal to 122/N N I . Because in mind that 2121/N N E E =, the input kV A which is approximately 11I E is also approximately equal to the output kV A, 22I E .The physical current has increased, and with in the primary leakage flux to which it is proportional. The total flux linking the primary,111Φ=Φ+Φ=Φm p is shown unchanged because the total back e.m.f., （dt d N E /111Φ-）is still equal and opposite to 1V . However, there has been a redistribution of flux and the mutualcomponent has fallen due to the increase of 1Φ with 1I . Although the change is small, the secondary demand could not be met without a mutual flux and e.m.f. alteration to permit primary current to change. The net flux s Φlinking the secondary winding has been further reduced by the establishment of secondary leakage flux due to 2I , and this opposes m Φ. Although m Φ and 2Φ are indicated separately, they combine to one resultant in the core which will be downwards at the instant shown. Thus the secondary terminal voltage is reduced to dt d N V S /22Φ-= which can be considered in two components, i.e. dt d N dt d N V m //2222Φ-Φ-=or vectorially 2222I jX E V -=. As for the primary, 2Φ is responsible for a substantially constantsecondary leakage inductance 222222/Λ=ΦN i N . It will be noticed that the primary leakage flux is responsible for part of the change in the secondary terminal voltage due to its effects on the mutual flux. The two leakage fluxes are closely related;2Φ, for example, by its demagnetizing action on m Φ has caused the changes on the primary side which led to the establishment of primary leakage flux.If a low enough leading power factor is considered, the total secondary flux and the mutual flux are increased causing the secondary terminal voltage to rise with load. p Φ is unchanged in magnitude from the no load condition since, neglecting resistance, it still has to provide a total back e.m.f. equal to 1V . It is virtually the same as 11Φ, though now produced by the combined effect of primary and secondary ampere-turns. The mutual flux must still change with load to give a change of 1E and permit more primary current to flow. 1E has increased this time but due to the vector combination with 1V there is still an increase of primary3current.Two more points should be made about the figures. Firstly, a unity turns ratio has been assumed for convenience so that '21E E =. Secondly, the physical picture is drawn for a different instant of time from the vector diagrams which show 0=Φm , if the horizontal axis is taken as usual, to be the zero time reference. There are instants in the cycle when primary leakage flux is zero, when the secondary leakage flux is zero, and when primary and secondary leakage flux is zero, and when primary and secondary leakage fluxes are in the same sense.The equivalent circuit already derived for the transformer with the secondary terminals open, can easily be extended to cover the loaded secondary by the addition of the secondary resistance and leakage reactance.Practically all transformers have a turn’s ratio different from unity although such an arrangement is sometimes employed for the purposes of electrically isolating one circuit from another operating at the same voltage. To explain the case where 21N N ≠ the reaction of the secondary will be viewed from the primary winding. The reaction is experienced only in terms of the magnetizing force due to the secondary ampere-turns. There is no way of detecting from the primary side whether 2I is large and 2N small or vice versa, it is the product of current and turns which causes the reaction. Consequently, a secondary winding can be replaced by any number of different equivalent windings and load circuits which will give rise to an identical reaction on the primary .It is clearly convenient to change the secondary winding to an equivalent winding having the same number of turns 1N as the primary.With 2N changes to 1N , since the e.m.f.s are proportional to turns,2212)/('E N N E = which is the same as 1E .For current, since the reaction ampere turns must be unchanged 1222'''N I N I = must be equal to 22N I .i.e. 2122)/(I N N I =.For impedance, since any secondary voltage V becomes V N N )/(21, and secondary current I becomes I N N )/(12, then any secondary impedance, including load impedance, must become I V N N I V /)/('/'221=. Consequently, 22212)/('R N N R = and 22212)/('X N N X = .If the primary turns are taken as reference turns, the process is called referring to the primary side.There are a few checks which can be made to see if the procedure outlined is valid.For example, the copper loss in the referred secondary winding must be the same as in the original secondary otherwise the primary would have to supply a different loss power.''222R I Must be equal to 222R I . ）222122122/()/(N N R N N I •• does in fact reduce to 222R I . Similarly the stored magnetic energy in the leakage field )2/1(2LI which isproportional to 22'X I will be found to check as ''22X I . The referred secondary2212221222)/()/(''I E N N I N N E I E kVA =•==.The argument is sound, though at first it may have seemed suspect. In fact, if the actual secondary winding was removed physically from the core and replaced by the equivalent winding and load circuit designed to give the parameters 1N ,'2R ,'2X and '2I , measurements from the primary terminals would be unable to detect any5difference in secondary ampere-turns, kVA demand or copper loss, under normal power frequency operation.There is no point in choosing any basis other than equal turns on primary and referred secondary, but it is sometimes convenient to refer the primary to the secondary winding. In this case, if all the subscript 1’s are interchanged for the subscript 2’s, the necessary referring constants are easily found; e.g. 2'1R R ≈,21'X X ≈; similarly 1'2R R ≈ and 12'X X ≈. The equivalent circuit for the general case where 21N N ≠ except that m r has been added to allow for iron loss and an ideal lossless transformation has been included before the secondary terminals to return '2V to 2V .All calculations of internal voltage and power losses are made before this ideal transformation is applied. The behavior of a transformer as detected at both sets of terminals is the same as the behavior detected at the corresponding terminals of this circuit when the appropriate parameters are inserted. The slightly different representation showing the coils 1N and 2N side by side with a core in between is only used for convenience. On the transformer itself, the coils are, of course, wound round the same core.Very little error is introduced if the magnetizing branch is transferred to the primary terminals, but a few anomalies will arise. For example, the current shown flowing through the primary impedance is no longer the whole of the primary current. The error is quite small since 0I is usually such a small fraction of 1I . Slightly different answers may be obtained to a particular problem depending on whether or not allowance is made for this error. With this simplified circuit, the primary and referred secondary impedances can be added to give:221211)/(Re N N R R += And 221211)/(N N X X Xe +=It should be pointed out that the equivalent circuit as derived here is only valid for normal operation at power frequencies; capacitance effects must be taken into account whenever the rate of change of voltage would give rise to appreciable capacitance currents,dt CdV I c /=. They are important at high voltages and at frequencies much beyond 100 cycles/sec. A further point is not the only possible equivalent circuit even for power frequencies .An alternative , treating the transformer as a three-or four-terminal network, gives rise to a representation which is just as accurate and has some advantages for the circuit engineer who treats all devices as circuit elements with certain transfer properties. The circuit on this basis would have a turns ratio having a phase shift as well as a magnitude change, and the impedances would not be the same as those of the windings. The circuit would not explain the phenomena within the device like the effects of saturation, so for an understanding of internal behavior.There are two ways of looking at the equivalent circuit:(a) viewed from the primary as a sink but the referred load impedance connected across '2V ,or(b) Viewed from the secondary as a source of constant voltage 1V with internal drops due to 1Re and 1Xe . The magnetizing branch is sometimes omitted in this representation and so the circuit reduces to a generator producing a constant voltage 1E (actually equal to 1V ) and having an internal impedance jX R + (actually equal to 11Re jXe +).In either case, the parameters could be referred to the secondary winding and this may save calculation time.The resistances and reactances can be obtained from two simple light load tests.7 负载运行的变压器通过选择合适的匝数比，一次侧输入电压1V 可任意转换成所希望的二次侧开路电压2E 。
关于变压器保护的20xx字英语文献
关于变压器保护的20xx字英语文献篇一：变压器英文文献Transformer short-circuit accident on the handling of Thoughts Astract: The accident in the transformer, the higher probability, a greater threat to the device is the transformer short circuit, especially the low pressure side of the transformer short-circuit. Transformer low voltage side to the incident after short inspection and processing to be described.Key words: Thinking transformer short-circuit accidentTreatment transformer short-circuit accident, first by checking, testing to find out the real problem lies; followed the process should also pay attention to related issues. Specific considerations are as follows:First, the transformer short-circuit accident inspection, testing. When subjected to sudden short-circuit transformers, high and low pressure side will be significant short-circuit current, no time off in a very short time circuit breaker, short circuit currents and current proportional to the square of the electric power to act on the transformer winding, This electric power can be divided into radial force and axial force. In short, the effect of radiation on the winding force of tension will be high voltage winding, low voltage windingunder pressure. Since winding round, round objects, the pressure ratio is more easily deformed by tension, therefore, more low-voltage winding deformation. Sudden short circuit in the axial force generated by the compression and the high and low voltage winding winding because the axial displacement, axial force is also acting on the core and clamps. Therefore, in face of sudden short-circuit the transformer, the most prone to deformation of the low-voltage winding and balanced winding, then the high voltage windings, core and clamps. Therefore, the transformershort-circuit accident, the inspection is to check the main winding, core, clamps and other parts.First, the winding of the inspection and testWhen the transformer short-circuit in the electric power under the action of winding the same time by pressing, pulling, bending and other forces acting, concealment caused by the failure of its strong, is not easy to check and repair, so the short circuit fault should focus on checking winding situation.(A) of the transformer DC resistance measurementAccording to the transformer DC resistance measurements to check the winding DC resistance unbalance and compared with previous measurements, can effectively examine the transformer winding damage. For example, a low voltage transformer short-circuit side after the accident to the DC resistance ofC increased by about 10% of new shares which may be winding to determine the situation, and finally winding hanging out, it was discovered off one phase winding C shares.(2) measurement of transformer winding capacitance.By the winding capacitance between the windings, and the cake layer capacitance and the winding-fat capacitor. This capacitor and the winding and core and in the gap, winding and core of the gap between the windings, the gap between cake layers and on. When the winding deformation, the general was “S”-shaped bend, which leads to winding on the core of the gap distance smaller, winding capacitance to ground will be larger, but the smaller the gap, the greater the capacitance changes, so winding electrical capacity can indirectly reflect the degree of winding deformation.(3) check after hanging hood.After lifting the transformer cover, check out the transformer ifinternal molten slag or copper slag or aluminum pieces of paper, high-density cable, you can determine the occurrence of a greater degree of winding deformation and off shares, etc. In addition, the shift from the winding Pad or off, clips and other bits, the pressure screw displacement can also determine the extent of the damage the windings. 2, core and clamps checks.Transformer core should have sufficient mechanical strength. Core of the mechanical strength is by all clamping on the core strength of their connections to guarantee. When the electric power generated when the winding, winding clamping axial force of the reaction will be offset, if the clamps, pull strength of less than the axial force plate when the clamps, pull board and the winding will be damaged. Therefore, we should carefully check the core, clamps, pull the state board and its connections.(1) Check the yoke iron core chips have ran up and down situation.(2) should be measured through the core and the core of the insulation resistance of the screw, check whether the damaged wearing coat-core screw; check the drawing board, drawing board connector for damage.(3) because of short circuit in the transformer, the plate and the clamps mayoccur between the displacement pressure of the nail plate and the yoke pulled off the ground connection, or over-current chip burning, so the plate for the winding, in addition to check the pressure screw, plate damaged, we must also check the winding and the pressure on the yoke screw and the ground connection is reliable.3, the analysis of transformer oil and gas.After suffering the impact of transformer short-circuit in the gas relay large amounts of gas may accumulate, it can be taken after the accident in the transformer gas relay the gas and oil inside the transformer for laboratory analysis, to determine the nature of theincident.Second, the transformer short-circuit fault handling precautions. 1, pieces of insulation should be replaced to ensure the performance of insulators.When dealing with the replacement of insulation parts should be tested for performance, and meet the requirements before use. In particular insulation on the lead frame wood attention should be paid. Wood should be placed before instal lation of about 80 ℃ hot transformer oil immersion period of time to ensure that the insulation of wood. 2, transformer oil filling the transformer insulation test should be conducted after 24 hours of rest.Because some of the moisture in the insulation pieces soak in the hot oil a longer time, the water will spread to the surface of insulation, if the fuelinjection after the test check the insulation defects often do not come out. For example, a 31.5MVA the 110kV transformer low voltage side of thereplacement of the treatment of a stent kV copper block, transformer filling of all the normal tests, 10kV low voltage side of the core, clamps, and insulation resis tance is reduced to about 1MΩ. Cover by hanging after examination, found that the stent 10kV copper block insulation is very low. Therefore, the transformer insulation test should be conducted 24 hours after the grease still more reliable.3, the core back to the equipment should be noted that the sharp corners.Installed in the back yoke, attention should be angular core chip, and timely measurement of oil duct insulation, in particular, pay attention to the oil channel at the chip corners, to prevent overlap resulting core chip multi-point grounding. For example, one of the 220kV120MVA transformers, replacementof the low pressure side of the winding back yoke installed, due to back loaded in the chip did not pay attention to sharp corners, and no timely measure the oil duct insulation, after installation of insulation to measure the oil channel 0Finally, take a long time to find the core chip, due to short circuit the oil channel sharp corners.关于处理变压器短路事故的几点思考摘要：在变压器事故中，发生概率较高、对设备威胁较大的就是变压器短路事故，特别是变压器低压侧发生短路。
美国变压器制作文章英文
美国变压器制作文章英文英文：Transformer manufacturing is a complex process that requires a lot of expertise and precision. As someone who has worked in the industry for several years, I can attest to the fact that it is not an easy job. However, the end result is always worth the effort.The first step in transformer manufacturing is to design the transformer. This involves determining the voltage and current requirements, as well as the physical size of the transformer. Once the design is complete, the next step is to select the appropriate materials. This includes the core, coil, and insulation materials.After the materials have been selected, the next stepis to assemble the transformer. This involves winding the coils, assembling the core, and connecting the coils to the core. Once the transformer has been assembled, it is testedto ensure that it meets the required specifications.One of the most important aspects of transformer manufacturing is quality control. Transformers are critical components in many electrical systems, and any defects or malfunctions can have serious consequences. As a result, it is essential to ensure that every transformer is thoroughly tested and inspected before it is released to the customer.In addition to quality control, another important aspect of transformer manufacturing is innovation. As technology advances, so do the requirements for transformers. Manufacturers must constantly adapt and improve their products to meet these changing needs.Overall, transformer manufacturing is a challenging but rewarding field. It requires a combination of technical expertise, precision, and innovation. However, the end result is a product that plays a critical role in many electrical systems.中文：变压器制造是一个复杂的过程，需要很多专业知识和精度。
Transformer 变压器 英文原版
TRANSFORMER1. INTRODUCTIONThe high-voltage transmission was need for the case electrical power is to be provided at considerable distance from a generating station. At some point this high voltage must be reduced, because ultimately is must supply a load. The transformer makes it possible for various parts of a power system to operate at different voltage levels. In this paper we discuss power transformer principles and applications.2. TOW-WINDING TRANSFORMERSA transformer in its simplest form consists of two stationary coils coupled by a mutual magnetic flux. The coils are said to be mutually coupled because they link a common flux.In power applications, laminated steel core transformers (to which this paper is restricted) are used. Transformers are efficient because the rotational losses normally associated with rotating machine are absent, so relatively little power is lost when transforming power from one voltage level to another. Typical efficiencies are in the range 92 to 99%, the higher values applying to the larger power transformers.The current flowing in the coil connected to the ac source is called the primary winding or simply the primary. It sets up the flux φ in the core, which varies periodically both in magnitude and direction. The flux links the second coil, called the secondary winding or simply secondary. The flux is changing; therefore, it induces a voltage in the secondary by electromagnetic induction in accordance with Lenz’s law. Thus the primary receives its power from the source while the secondary supplies this power to the load. This action is known as transformer action.3. TRANSFORMER PRINCIPLESWhen a sinusoidal voltage Vp is applied to the primary with the secondary open-circuited, there will be no energy transfer. The impressed voltage causes a small current I0 to flow in the primary winding. This no-load current has two functions: (1) it produces the magnetic flux in the core, which varies sinusoidally between zero and φm, where φm is the maximum value of the core flux; and (2) it provides a component to account for the hysteresis and eddy current losses in the core. There combined losses are normally referred to as the core losses.The no-load current I0 is usually few percent of the rated full-load current of the transformer (about 2 to 5%). Since at no-load the primary winding acts as a large reactance due to the iron core, the no-load current will lag the primary voltage by nearly 90º. It is readily seen that the current component Im= I0sinθ0, called the magnetizing current, is 90º in phase behind the primary voltage VP. It is this component that sets up the flux in the core; φ is therefore in phase with Im.The second component, Ie=I0sinθ0, is in phase with the primary voltage. It is the current component that supplies the core losses. The phasor sum of these two components represents the no-load current, orI0 = Im+ IeIt should be noted that the no-load current is distortes and nonsinusoidal. This is the result of the nonlinear behavior of the core material.If it is assumed that there are no other losses in the transformer, the induced voltage In the primary, Ep and that in the secondary, Es can be shown. Since the magnetic flux set up by the primary winding ，there will be an induced EMF E in the secondary winding in accordance with Faraday’s law, namely, E=N Δφ/Δt. This same flux also links the primary itself, inducing in it an EMF, Ep. As discussed earlier, the induced voltage must lag the flux by 90º, therefore, they are 180º out of phase with the applied voltage. Since no current flows in the secondary winding, Es=Vs. The no-load primary current I0 is small, a few percent of full-load current. Thus the voltage in the primary is small and Vp is nearly equal to Ep. The primary voltage and the resulting flux are sinusoidal; thus the induced quantities Ep and Es vary as a sine function. The average value of the induced voltage given bywhich is Faraday’s law applied to a finite time interval. It follows thatEavg =()N 2f 12m ϕ = 4fN φmwhich N is the number of turns on the winding. Form ac circuit theory, the effective or root-mean-square (rms) voltage for a sine wave is 1.11 times the average voltage; thusE = 4.44fN φmSince the same flux links with the primary and secondary windings, the voltage per turn in each winding is the same. HenceEp = 4.44fNp φm andEs = 4.44fNs φmwhere Ep and Es are the number of turn on the primary and secondary windings, respectively. The ratio of primary to secondary induced voltage is called the transformation ratio. Denoting this ratio by a, it is seen thata =S P E E = SP N NAssume that the output power of a transformer equals its input power, not a bad sumption inpractice considering the high efficiencies. What we really are saying is that we are dealing with anideal transformer; that is, it has no losses. ThusPm = Pout orVpIp × primary PF = VsIs × secondary PFwhere PF is the power factor. For the above-stated assumption it means that the power factor on primary and secondary sides are equal; thereforeVpIp = VsIsfrom which is obtainedS P V V = S P I I ≌ S P E E ≌ aIt shows that as an approximation the terminal voltage ratio equals the turns ratio. The primary and secondary current, on the other hand, are inversely related to the turns ratio. The turns ratio gives a measure of how much the secondary voltage is raised or lowered in relation to the primary voltage. To calculate the voltage regulation, we need more information.The ratio of the terminal voltage varies somewhat depending on the load and its power factor. In practice, the transformation ratio is obtained from the nameplate data, which list the primary and secondary voltage under full-load condition.When the secondary voltage Vs is reduced compared to the primary voltage, the transformation is said to be a step-down transformer: conversely, if this voltage is raised, it is called a step-up transformer. In a step-down transformer the transformation ratio a is greater than unity (a>1.0), while for a step-up transformer it is smaller than unity (a<1.0). In the event that a=1, the transformer secondary voltage equals the primary voltage. This is a special type of transformer used in instances where electrical isolation is required between the primary and secondary circuit while maintaining the same voltage level. Therefore, this transformer is generally knows as an isolation transformer.As is apparent, it is the magnetic flux in the core that forms the connecting link between primary and secondary circuit. In section 4 it is shown how the primary winding current adjusts itself to the secondary load current when the transformer supplies a load.Looking into the transformer terminals from the source, an impedance is seen which by definition equals Vp / Ip. From S P = V V S P ≌I I SP E E ≌ a , we have Vp = aVs and Ip = Is/a.In terms of Vs and Is the ratio of Vp to Ip isP P I V =a a S S I V = SS I V a 2But Vs / Is is the load impedance ZL thus we can say thatZm (primary) = a2ZLThis equation tells us that when an impedance is connected to the secondary side, it appears from the source as an impedance having a magnitude that is a2 times its actual value. We say that the load impedance is reflected or referred to the primary. It is this property of transformers that is used in impedance-matching applications.4. TRANSFORMERS UNDER LOADThe primary and secondary voltages shown have similar polarities, as indicated by the “dot-making” convention. The dots near the upper ends of the windings have the same meaning as in circuit theory; the marked terminals have the same polarity. Thus when a load is connected to the secondary, the instantaneous load current is in the direction shown. In other words, the polarity markings signify that when positive current enters both windings at the marked terminals, the MMFs of the two windings add.Since the secondary voltage depends on the core flux φ0, it must be clear that the flux should not change appreciably if Es is to remain essentially constant under normal loading conditions. With the load connected, a current Is will flow in the secondary circuit, because the induced EMF Es will act as a voltage source. The secondary current produces an MMF NsIs that creates a flux. This flux has such a direction that at any instant in time it opposes the main flux that created it in the first place. Of course, this is Lenz’s law in action. Thus the MMF represented by NsIs tends to reduce the core flux φ0. This means that the flux linking the primary winding reduces and consequently the primary induced voltage Ep, This reduction in induced voltage causes a greater difference between the impressed voltage and the counter induced EMF, thereby allowing more current to flow in the primary. The fact that primary current Ip increases means that the two conditions stated earlier are fulfilled: (1) the power input increases to match the power output, and (2) the primary MMF increases to offset the tendency of the secondary MMF to reduce the flux.In general, it will be found that the transformer reacts almost instantaneously to keep the resultant core flux essentially constant. Moreover, the core flux φ0 drops very slightly between n o load and full load (about 1 to 3%), a necessary condition if Ep is to fall sufficiently to allow an increase in Ip.On the primary side, Ip’ is the current that flows in the primary to balance the demagnetizing effect of Is. Its MMF NpIp’ sets up a flux linking the primary only. Since the core flux φ0 remains constant. I0 must be the same current that energizes the transformer at no load. The primary current Ip is therefore the sum of the current Ip’ and I0.Because the no-load current is relatively small, it is correct to assume that the primary ampere-turns equal the secondary ampere-turns, since it is under this condition that the core flux is essentially constant. Thus we will assume that I0 is negligible, as it is only a small component of the full-load current.When a current flows in the secondary winding, the resulting MMF (NsIs) creates a separate flux, apart from the flux φ0 produced by I0, which links the secondary winding only. This flux does no link with the primary winding and is therefore not a mutual flux.In addition, the load current that flows through the primary winding creates a flux that links with the primary winding only; it is called the primary leakage flux. The secondary- leakage fluxgives rise to an induced voltage that is not counter balanced by an equivalent induced voltage in the primary. Similarly, the voltage induced in the primary is not counterbalanced in the secondary winding. Consequently, these two induced voltages behave like voltage drops, generally called leakage reactance voltage drops. Furthermore, each winding has some resistance, which produces a resistive voltage drop. When taken into account, these additional voltage drops would complete the equivalent circuit diagram of a practical transformer. Note that the magnetizing branch is shown in this circuit, which for our purposes will be disregarded. This follows our earlier assumption that the no-load current is assumed negligible in our calculations. This is further justified in that it is rarely necessary to predict transformer performance to such accuracies. Since the voltage drops are all directly proportional to the load current, it means that at no-load conditions there will be no voltage drops in either winding.。
变压器电感矩阵模型-外文文献翻译
1Research of transformer modeling considering the influence of tap positions on original parametersLiu J, Asad A, Nie K, et al. Research of transformer modeling considering the influence of tap positions on original parameters[C]// Power and Energy Engineering Conference. IEEE, 2016:2209-2214.摘要-传统的变压器模型假定在研究电力系统潮流，电磁和机电仿真时，分接位置只影响匝数比。
发现变压器的原始参数，如绕组电阻和电感，也随不同抽头位置而变化。
基于磁路定律，提出了变压器电感矩阵模型。
模型中的参数可以通过变压器型式测试获得。
进行潮流计算案例研究，以证明由不同分接头位置引起的变压器原始参数的偏差，可能会造成相当大的计算误差。
2 Stray parameters in high-voltage, high-frequency transformer传统的高压高频变压器（HHT）需要精心设计，因为频率增加所带来的各种要求，通常高达几十kHz。
在所有设计问题中，包括漏电感和杂散电容的杂散参数是重要的。
本文首先分析了HHT的杂散参数的源和常用计算方法，并对几种常用的最小化设计方法进行了分析比较，为HHT的设计提供了参考。
3 Design Methodology and Optimization of a Medium-Frequency Transformer for High-Power DC–DC Applications用于大功率DC-DC应用的中频变压器的设计方法和优化抽象：中频电力变压器（MFPT）是未来全直流海上风电场，牵引和固态变压器等应用中的隔离双向dc-dc转换器的关键要素之一。
变压器-外文翻译
-TransformerA Transformer is a device that change ac electric energy at one voltage level into ac electric energy at another voltage level through the action of a magnetic filed .It consists of two or more coils of wire wrapped a common ferromagnetic core. These coils are (usually) not directly connected. The only connection between the coils is the common magnetic flux present within the core.One of the transformer windings is connected to a source of ac electric power, and the second (and perhaps third) transformer winding supplies electric power to loads. The transformer winding connected to the power source is called the primary winding or input winding, and the winding connected to the loads is called the secondary winding or output winding. If there is a third winding on the transformer, it is called the tertiary winding.Power transformers are constructed on one of two types of cores. One type of construction consists of a simple rectangular laminated piece of steel with the transformer windings wrapped around two sides of the rectangle. This type of construction is known as core form.可编辑-The other type consists of a three-legged laminated core with the windings wrapped around the center leg. This type of construction is known as shell form. In either case, the core is constructed of thin laminations electrically isolated from each other in order to reduce eddy currents to a minimum.Power transformers are given a variety of different names, depending on their use in power systems. A transformer connected to the output of a generator and used to step its voltage up to transmission levels is sometimes called a unit transformer. The transformer at the other end of the transmission line, which steps the voltage down from transmission levels to distribution levels, is called a substation transformer. Finally, the transformer that takes the distribution voltage and steps it down to the final voltage at which the power is actually used is called a distribution transformer. All these devices are essentially the same the only difference among them is their intended use.In addition to the various power transformers, two special-purpose transformers are used with electric machinery and power systems. The first of these special transformers is a device specially designed to sample a high voltage and produce a low secondary voltage可编辑-directly proportional to it, Such a transformer is called a potential transformer. A power transformer also produces a secondary voltage directly proportional to its primary voltage the difference between a potential transformer and a power transformer is that the potential transformer is designed to handle only a very small current. The second type of special transformer is a device designed to provide a secondary current much small than but directly proportional to its primary current. This device is called a current transformerThe ideal transformer without loss of energy, so have a 100% efficiency. In reality, the efficiency of power transformer reaches 98%, But small transformer loss will be more serious, and they may be less than 85% of efficiency. The energy loss from transformer in these phenomena: (in a coil of narrative, conductive are called "core"The current through the winding resistance, thermal conductive (current generated when the heat to higher, the human body to feel energy losses caused to). And other kinds of loss, this loss not from the core transformer.Eddy: the magnetic loss to generate electricity, iron loop back into heat energy and loss caused to the outside可编辑-world. The core of don't cut into thin can reduce the loss.Magnetism loss: all are not both senders coils magnetic field lines are receiving causes energy drain.Hysteresis: core lagged effect of magnetic field changes that every cause loss of energy. This depends on the size of the loss of the core materials.Alternating magnetic field strength loss: that wire, iron and near the electromagnetic force between the metal forming and changing the vibration and energy drain.Magnetostrictive: the magnetic field that appear alternately core.If the core material susceptible to expansion effect of friction between the molecules, will lead to loss of energy.Cooling equipment: large transformer with cooling fan with general of water pump, or the radiator. These devices have been using energy generally count the energy loss of transformer.The overhead three phase power transmission line is the main energy corridor in a power system. One might assume that the circuit model would be trivial (ideal conductors), but three different phenomena produce effects that can not reasonably be ignored. In order of importance, they are the series voltages induced by the可编辑-magnetic fields surrounding the conductors, the shunt displacement currents resulting from the electric fields between conductors，and the ohmic resistance of the conductor material. A forth，and minor, effect is the leakage conduction current that flows through contamination films on the insulators．The overhead neutrals of a typical overhead power transmission line are electrically in contact with the tower and therefore grounded, They primarily exists to provide lightning shielding for the phase conductors and also to carry zero sequence and harmonic currents that help to maintain balanced sinusoidal voltages. They are usually steel or aluminum and are small (diameter about lcm)．The phase conductors are much larger (diameter about 5cm), and are typically stranded a1uminum surrounding a stranded steel cable (for increased tensile strength). sometimes more than one (a "bundle") comprise a phase．A11 are bare (no insulating covering) for heat dissipation reasons; the phase conductors are insulated from each other and the tower by suspension from insulator strings.可编辑-变压器变压器是通过磁场作用将交流电从某一电压等级转换至另一个电压级别的设备。
文献翻译-负载运行的变压器及直流电机导论
The Transformer on load ﹠Introduction to DC Machine sThe Transformer on loadIt has been shown that a primary input voltage 1V can be transformed to any desired open-circuit secondary voltage 2E by a suitable choice of turns ratio. 2E is available for circulating a load current impedance. For the moment, a lagging power factor will be considered. The secondary current and the resulting ampere-turns 22N I will change the flux, tending to demagnetize the core, reduce m Φ and with it 1E . Because the primary leakage impedance drop is so low, a small alteration to 1E will cause an appreciable increase of primary current from 0I to a new value of 1I equal to ()()i jX R E V ++111/. The extra primary current and ampere-turns nearly cancel the whole of the secondary ampere-turns. This being so , the mutual flux suffers only a slight modification and requires practically the same net ampere-turns 10N I as on no load. The total primary ampere-turns are increased by an amount 22N I necessary to neutralize the same amount of secondary ampere-turns. In the vector equation , 102211N I N I N I =+; alternatively, 221011N I N I N I -=. At full load, the current 0I is only about 5% of the full-load current and so 1I is nearly equal to 122/N N I . Because in mind that 2121/N N E E =, the input kV A which is approximately 11I E is also approximately equal to the output kV A, 22I E .The physical current has increased, and with in the primary leakage flux to which it is proportional. The total flux linking the primary ,111Φ=Φ+Φ=Φm p , is shown unchanged because the total back e.m.f.,（dt d N E /111Φ-）is still equal and opposite to 1V . However, there has been a redistribution of flux and the mutual component has fallen due to the increase of 1Φ with 1I . Although the change is small, the secondary demand could not be met without a mutual flux and e.m.f. alteration to permit primary current to change. The net flux s Φlinking the secondary winding has been further reduced by the establishment of secondary leakage flux due to 2I , and this opposes m Φ. Although m Φ and2Φ are indicated separately , they combine to one resultant in the core which will be downwards at the instant shown. Thus the secondary terminal voltage is reduced to dt d N V S /22Φ-= which can be considered in two components, i.e. dt d N dt d N V m //2222Φ-Φ-=or vectorially 2222I jX E V -=. As for the primary, 2Φ is responsible for a substantially constant secondaryleakage inductance 222222/Λ=ΦN i N . It will be noticed that the primary leakage flux is responsiblefor part of the change in the secondary terminal voltage due to its effects on the mutual flux. The two leakage fluxes are closely related; 2Φ, for example, by its demagnetizing action on m Φ has caused the changes on the primary side which led to the establishment of primary leakage flux.If a low enough leading power factor is considered, the total secondary flux and the mutual flux are increased causing the secondary terminal voltage to rise with load. p Φ is unchanged in magnitude from the no load condition since, neglecting resistance, it still has to provide a total back e.m.f. equal to 1V . It is virtually the same as 11Φ, though now produced by the combined effect of primary and secondary ampere-turns. The mutual flux must still change with load to give a change of 1E and permit more primary current to flow. 1E has increased this time but due to the vector combination with 1V there is still an increase of primary current.Two more points should be made about the figures. Firstly, a unity turns ratio has been assumed for convenience so that '21E E =. Secondly, the physical picture is drawn for a different instant of time from the vector diagrams which show 0=Φm , if the horizontal axis is taken as usual, to be the zero time reference. There are instants in the cycle when primary leakage flux is zero, when the secondary leakage flux is zero, and when primary and secondary leakage flux is zero, and when primary and secondary leakage fluxes are in the same sense.The equivalent circuit already derived for the transformer with the secondary terminals open, can easily be extended to cover the loaded secondary by the addition of the secondary resistance and leakage reactance.Practically all transformers have a turns ratio different from unity although such an arrangement issometimes employed for the purposes of electrically isolating one circuit from another operating at the same voltage. To explain the case where 21N N ≠ the reaction of the secondary will be viewed from the primary winding. The reaction is experienced only in terms of the magnetizing force due to the secondary ampere-turns. There is no way of detecting from the primary side whether 2I is large and 2N small or vice versa, it is the product of current and turns which causes the reaction. Consequently, a secondary winding can be replaced by any number of different equivalent windings and load circuits which will give rise to an identical reaction on the primary .It is clearly convenient to change the secondary winding to an equivalent winding having the same number of turns 1N as the primary.With 2N changes to 1N , since the e.m.f.s are proportional to turns, 2212)/('E N N E = which is the same as 1E .For current, since the reaction ampere turns must be unchanged 1222'''N I N I = must be equal to 22N I .i.e. 2122)/(I N N I =.For impedance , since any secondary voltage V becomes V N N )/(21, and secondary current I becomes I N N )/(12, then any secondary impedance, including load impedance, must become I V N N I V /)/('/'221=. Consequently, 22212)/('R N N R = and 22212)/('X N N X = .If the primary turns are taken as reference turns, the process is called referring to the primary side. There are a few checks which can be made to see if the procedure outlined is valid.For example, the copper loss in the referred secondary winding must be the same as in the original secondary otherwise the primary would have to supply a different loss power. ''222R I must be equal to 222R I . ）222122122/()/(N N R N N I ∙∙ does in fact reduce to 222R I .Similarly the stored magnetic energy in the leakage field )2/1(2LI which is proportional to 22'X I will be found to check as ''22X I . The referred secondary 2212221222)/()/(''I E N N I N N E I E kVA =∙==.The argument is sound, though at first it may have seemed suspect. In fact, if the actual secondarywinding was removed physically from the core and replaced by the equivalent winding and load circuit designed to give the parameters 1N ,'2R ,'2X and '2I , measurements from the primary terminals would be unable to detect any difference in secondary ampere-turns, kVA demand or copper loss, under normal power frequency operation.There is no point in choosing any basis other than equal turns on primary and referred secondary, but it is sometimes convenient to refer the primary to the secondary winding. In this case, if all the subscript 1’s are interchanged for the subscript 2’s, the necessary referring constants are easily found; e.g. 2'1R R ≈,21'X X ≈; similarly 1'2R R ≈ and 12'X X ≈.The equivalent circuit for the general case where 21N N ≠ except that m r has been added to allow for iron loss and an ideal lossless transformation has been included before the secondary terminals to return '2V to 2V .All calculations of internal voltage and power losses are made before this ideal transformation is applied. The behaviour of a transformer as detected at both sets of terminals is the same as the behaviour detected at the corresponding terminals of this circuit when the appropriate parameters are inserted. The slightly different representation showing the coils 1N and 2N side by side with a core in between is only used for convenience. On the transformer itself, the coils are , of course , wound round the same core.Very little error is introduced if the magnetising branch is transferred to the primary terminals, but a few anomalies will arise. For example ,the current shown flowing through the primary impedance is no longer the whole of the primary current. The error is quite small since 0I is usually such a small fraction of 1I . Slightly different answers may be obtained to a particular problem depending on whether or not allowance is made for this error. With this simplified circuit, the primary and referred secondary impedances can be added to give: 221211)/(Re N N R R += and 221211)/(N N X X Xe +=It should be pointed out that the equivalent circuit as derived here is only valid for normal operation at power frequencies; capacitance effects must be taken into account whenever the rate of change of voltage would give rise to appreciable capacitance currents, dt CdV I c /=. They are important at high voltages and at frequencies much beyond 100 cycles/sec. A further point is not theonly possible equivalent circuit even for power frequencies .An alternative , treating the transformer as a three-or four-terminal network, gives rise to a representation which is just as accurate and has some advantages for the circuit engineer who treats all devices as circuit elements with certain transfer properties. The circuit on this basis would have a turns ratio having a phase shift as well as a magnitude change, and the impedances would not be the same as those of the windings. The circuit would not explain the phenomena within the device like the effects of saturation, so for an understanding of internal behaviour .There are two ways of looking at the equivalent circuit:(a) viewed from the primary as a sink but the referred load impedance connected across '2V ,or (b) viewed from the secondary as a source of constant voltage 1V with internal drops due to 1Re and 1Xe . The magnetizing branch is sometimes omitted in this representation and so the circuit reduces to a generator producing a constant voltage 1E (actually equal to 1V ) and having an internal impedance jX R + (actually equal to 11Re jXe +).In either case, the parameters could be referred to the secondary winding and this may save calculation time .The resistances and reactances can be obtained from two simple light load tests.Introduction to DC MachinesDC machines are characterized by their versatility. By means of various combination of shunt, series, and separately excited field windings they can be designed to display a wide variety of volt-ampere or speed-torque characteristics for both dynamic and steadystate operation. Because of the ease with which they can be controlled , systems of DC machines are often used in applications requiring a wide range of motor speeds or precise control of motor output.The essential features of a DC machine are shown schematically. The stator has salient poles and is excited by one or more field coils. The air-gap flux distribution created by the field winding is symmetrical about the centerline of the field poles. This axis is called the field axis or direct axis.As we know , the AC voltage generated in each rotating armature coil is converted to DC in the external armature terminals by means of a rotating commutator and stationary brushes to which the armature leads are connected. The commutator-brush combination forms a mechanical rectifier,resulting in a DC armature voltage as well as an armature m.m.f. wave which is fixed in space. The brushes are located so that commutation occurs when the coil sides are in the neutral zone , midway between the field poles. The axis of the armature m.m.f. wave then in 90 electrical degrees from the axis of the field poles, i.e., in the quadrature axis. In the schematic representation the brushes are shown in quarature axis because this is the position of the coils to which they are connected. The armature m.m.f. wave then is along the brush axis as shown.. (The geometrical position of the brushes in an actual machine is approximately 90 electrical degrees from their position in the schematic diagram because of the shape of the end connections to the commutator.)The magnetic torque and the speed voltage appearing at the brushes are independent of the spatial waveform of the flux distribution; for convenience we shall continue to assume a sinusoidal flux-density wave in the air gap. The torque can then be found from the magnetic field viewpoint.The torque can be expressed in terms of the interaction of the direct-axis air-gap flux per pole d Φ and the space-fundamental component 1a F of the armature m.m.f. wave . With the brushes in the quadrature axis, the angle between these fields is 90 electrical degrees, and its sine equals unity. For a P pole machine 12)2(2a d F P T ϕπ= In which the minus sign has been dropped because the positive direction of the torque can be determined from physical reasoning. The space fundamental 1a F of the sawtooth armature m.m.f. wave is 8/2π times its peak. Substitution in above equation then gives a d a a d a i K i mPC T ϕϕπ==2 Where a i =current in external armature circuit;a C =total number of conductors in armature winding;m =number of parallel paths through winding;And mPC K a a π2=Is a constant fixed by the design of the winding.The rectified voltage generated in the armature has already been discussed before for an elementary single-coil armature. The effect of distributing the winding in several slots is shown in figure ,in which each of the rectified sine waves is the voltage generated in one of the coils, commutation taking place at the moment when the coil sides are in the neutral zone. The generated voltage as observed from the brushes is the sum of the rectified voltages of all the coils in series between brushes and is shown by the rippling line labeled a e in figure. With a dozen or so commutator segments per pole, the ripple becomes very small and the average generated voltage observed from the brushes equals the sum of the average values of the rectified coil voltages. The rectified voltage a e between brushes, known also as the speed voltage, is m d a m d a a W K W mPC e ϕϕπ==2 Where a K is the design constant. The rectified voltage of a distributed winding has the same average value as that of a concentrated coil. The difference is that the ripple is greatly reduced.From the above equations, with all variable expressed in SI units:m a a Tw i e =This equation simply says that the instantaneous electric power associated with the speed voltage equals the instantaneous mechanical power associated with the magnetic torque , the direction of power flow being determined by whether the machine is acting as a motor or generator.The direct-axis air-gap flux is produced by the combined m.m.f. f f i N ∑ of the field windings, the flux-m.m.f. characteristic being the magnetization curve for the particular iron geometry of the machine. In the magnetization curve, it is assumed that the armature m.m.f. wave is perpendicular to the field axis. It will be necessary to reexamine this assumption later in this chapter, where the effects of saturation are investigated more thoroughly. Because the armature e.m.f. is proportional to flux timesspeed, it is usually more convenient to express the magnetization curve in terms of the armature e.m.f. 0a e at a constant speed 0m w . The voltage a e for a given flux at any other speed m w is proportional to the speed,i.e. 00a m m a e w w e Figure shows the magnetization curve with only one field winding excited. This curve can easily be obtained by test methods, no knowledge of any design details being required.Over a fairly wide range of excitation the reluctance of the iron is negligible compared with that of the air gap. In this region the flux is linearly proportional to the total m.m.f. of the field windings, the constant of proportionality being the direct-axis air-gap permeance.The outstanding advantages of DC machines arise from the wide variety of operating characteristics which can be obtained by selection of the method of excitation of the field windings. The field windings may be separately excited from an external DC source, or they may be self-excited; i.e., the machine may supply its own excitation. The method of excitation profoundly influences not only the steady-state characteristics, but also the dynamic behavior of the machine in control systems.The connection diagram of a separately excited generator is given. The required field current is a very small fraction of the rated armature current. A small amount of power in the field circuit may control a relatively large amount of power in the armature circuit; i.e., the generator is a power amplifier. Separately excited generators are often used in feedback control systems when control of the armature voltage over a wide range is required. The field windings of self-excited generators may be supplied in three different ways. The field may be connected in series with the armature, resulting in a shunt generator, or the field may be in two sections, one of which is connected in series and the other in shunt with the armature, resulting in a compound generator. With self-excited generators residual magnetism must be present in the machine iron to get the self-excitation process started.In the typical steady-state volt-ampere characteristics, constant-speed primemovers being assumed. The relation between the steady-state generated e.m.f. a E and the terminal voltage t V isa a a t R I E V -=Where a I is the armature current output and a R is the armature circuit resistance. In a generator, a E is large than t V ; and the electromagnetic torque T is a countertorque opposing rotation.The terminal voltage of a separately excited generator decreases slightly with increase in the load current, principally because of the voltage drop in the armature resistance. The field current of a series generator is the same as the load current, so that the air-gap flux and hence the voltage vary widely with load. As a consequence, series generators are not often used. The voltage of shunt generators drops off somewhat with load. Compound generators are normally connected so that the m.m.f. of the series winding aids that of the shunt winding. The advantage is that through the action of the series winding the flux per pole can increase with load, resulting in a voltage output which is nearly constant. Usually, shunt winding contains many turns of comparatively heavy conductor because it must carry the full armature current of the machine. The voltage of both shunt and compound generators can be controlled over reasonable limits by means of rheostats in the shunt field. Any of the methods of excitation used for generators can also be used for motors. In the typical steady-state speed-torque characteristics, it is assumed that the motor terminals are supplied from a constant-voltage source. In a motor the relation between the e.m.f. a E generated in the armature and the terminal voltage t V isa a a t R I E V +=Where a I is now the armature current input. The generated e.m.f. a E is now smaller than the terminal voltage t V , the armature current is in the opposite direction to that in a motor, and the electromagnetic torque is in the direction to sustain rotation ofthe armature.In shunt and separately excited motors the field flux is nearly constant. Consequently, increased torque must be accompanied by a very nearly proportional increase in armature current and hence by a small decrease in counter e.m.f. to allow this increased current through the small armature resistance. Since counter e.m.f. is determined by flux and speed, the speed must drop slightly. Like the squirrel-cage induction motor ,the shunt motor is substantially a constant-speed motor having about 5 percent drop in speed from no load to full load. Starting torque and maximum torque are limited by the armature current that can be commutated successfully.An outstanding advantage of the shunt motor is ease of speed control. With a rheostat in the shunt-field circuit, the field current and flux per pole can be varied at will, and variation of flux causes the inverse variation of speed to maintain counter e.m.f. approximately equal to the impressed terminal voltage. A maximum speed range of about 4 or 5 to 1 can be obtained by this method, the limitation again being commutating conditions. By variation of the impressed armature voltage, very wide speed ranges can be obtained.In the series motor, increase in load is accompanied by increase in the armature current and m.m.f. and the stator field flux (provided the iron is not completely saturated). Because flux increases with load, speed must drop in order to maintain the balance between impressed voltage and counter e.m.f.; moreover, the increase in armature current caused by increased torque is smaller than in the shunt motor because of the increased flux. The series motor is therefore a varying-speed motor with a markedly drooping speed-load characteristic. For applications requiring heavy torque overloads, this characteristic is particularly advantageous because the corresponding power overloads are held to more reasonable values by the associated speed drops. Very favorable starting characteristics also result from the increase in flux with increased armature current.In the compound motor the series field may be connected either cumulatively, so that its.m.m.f.adds to that of the shunt field, or differentially, so that it opposes. The differential connection is very rarely used. A cumulatively compounded motor hasspeed-load characteristic intermediate between those of a shunt and a series motor, the drop of speed with load depending on the relative number of ampere-turns in the shunt and series fields. It does not have the disadvantage of very high light-load speed associated with a series motor, but it retains to a considerable degree the advantages of series excitation.The application advantages of DC machines lie in the variety of performance characteristics offered by the possibilities of shunt, series, and compound excitation. Some of these characteristics have been touched upon briefly in this article. Still greater possibilities exist if additional sets of brushes are added so that other voltages can be obtained from the commutator. Thus the versatility of DC machine systems and their adaptability to control, both manual and automatic, are their outstanding features.负载运行的变压器及直流电机导论负载运行的变压器通过选择合适的匝数比，一次侧输入电压1V 可任意转换成所希望的二次侧开路电压2E 。
变压器工作原理英文
The Working Principles of Transformers Transformers are essential devices used in electrical power systems for voltage transformation. They play a crucial role in ensuring the efficient transmission and distribution of electricity. This document will provide an overview of the working principles of transformers.Introduction to TransformersA transformer consists of two or more coils of wire wound around a common magnetic core. The core is typically made of laminated iron to minimize energy losses due to eddy currents. The coils are referred to as the primary and secondary windings.The primary winding is connected to the input voltage source, while the secondary winding is connected to the load. The input voltage applied to the primary winding induces a fluctuating magnetic field in the core. This field induces a voltage in the secondary winding, which is then used to power the load.Faraday’s Law of Electromagnetic InductionThe operation of a transformer is based on Faraday’s law of electromagnetic induction. According to this law, when the magnetic field linking a conductor changes, an electromotive force (EMF) or voltage is induced in the conductor. This voltage is proportional to the rate at which the magnetic field changes.In a transformer, the primary winding is connected to an alternating current (AC) power source. As the AC voltage varies, it creates a changing magnetic field in the core. This changing magnetic field induces a voltage in the secondary winding, which is proportional to the number of turns in the winding.Step-up and Step-down TransformersTransformers can be either step-up or step-down, depending on the voltage ratio between the primary and secondary windings. A step-up transformer increases the voltage from the primary to the secondary winding, while a step-down transformer decreases the voltage.The voltage ratio in a transformer is determined by the ratio of the number of turns in the primary and secondary windings. For example, if the primary winding has 100 turns and the secondary winding has 200 turns, the voltage in the secondary winding will be twice the voltage in the primary winding.Step-up transformers are commonly used in power transmission, where high voltages are required to minimize energy losses over long distances. Step-downtransformers are used in applications where lower voltages are needed for safe and efficient operation.Ideal Transformer ModelIn an ideal transformer, the magnetic field in the core is perfectly coupled between the primary and secondary windings. This means that all the magnetic flux created by the primary winding links the secondary winding. In addition, there are no energy losses due to resistance or leakage inductance.Based on this ideal model, the voltage ratio in a transformer is given by the turns ratio. The turns ratio is the ratio of the number of turns in the secondary winding (Ns) to the number of turns in the primary winding (Np). Mathematically, it can be expressed as:Voltage ratio = Ns / NpThe ideal transformer model simplifies transformer analysis and design. However, real-world transformers have losses and non-ideal characteristics that need to be considered.Transformer Efficiency and LossesTransformers are not perfect and suffer from energy losses due to various factors. The major losses in transformers include copper losses and core losses.Copper losses occur due to the resistance of the wires in the windings. When current flows through the windings, heat is generated due to the resistance. These losses can be minimized by using wires with low resistance and increasing the size of the conductors.Core losses, also known as iron losses, occur due to hysteresis and eddy currents in the core material. Hysteresis losses are caused by the magnetic domains in the core repeatedly aligning and realigning with the changing magnetic field. Eddy current losses are caused by circulating currents induced in the core material. These losses can be reduced by using laminated iron cores and materials with low hysteresis and eddy current losses.The efficiency of a transformer is the ratio of output power to input power. Efficiency = (Output Power / Input Power) * 100%. It is desirable to have high-efficiency transformers to minimize energy losses.Transformer ApplicationsTransformers have numerous applications in electrical power systems. Some common applications include:1.Power transmission: Transformers are used to step up the voltage forefficient long-distance transmission of electricity.2.Power distribution: Transformers are used to step down the voltagefor safe and efficient distribution to homes and businesses.3.Voltage regulation: Transformers are used to regulate and stabilizevoltage levels in power systems.4.Electrical isolation: Transformers provide electrical isolation betweeninput and output circuits, preventing the transfer of hazardous voltages.5.Industrial applications: Transformers are used in various industrialprocesses, such as welding, electroplating, and electrolysis.6.Instrumentation: Transformers are used in instruments andmeasuring devices to step down voltage levels for accurate measurements.In conclusion, transformers are vital devices that enable the efficient transmission, distribution, and utilization of electrical energy. By understanding the working principles and characteristics of transformers, engineers can design and operate power systems effectively.。
Transformer变压器外文文献翻译
Transformer变压器One of the most valuable apparatus in electric power system is the transformer, for it enables us to utilize different voltage levels across the system for the most economical value. Generation of power at the synchronous machine level is normally at a relatively low voltage，which is most desirable economically．Stepping up of this generated voltage to high voltage，extra-high voltage or even to ultra-high voltage is done through power transformers to suit the power transmission requirement to minimize losses and increase the transmission capacity of the lines．This transmission voltage level is then stepped down in many stages for distribution and utilization purposes．电力系统中的最有价值之一是器具的变压器，它使我们能够利用不同电压等级，整个系统的最经济的值。
通常在较低功率在同步计算机级别的一代是voltage，which，是最理想的economically．Stepping 高voltage，extra 高电压该生成电压或甚至超高电压通过以适应电力传输的要求，尽量减少损失的电力变压器和增加lines．This 输电电压等级的输电量然后走在很多阶段的分布和利用的目的最有价值的一个装置在电力系统变压器,因为它使我们能够利用不同系统电压水平在最经济的价值。
变压器-外文翻译
外文翻译TransformerA Transformer is a device that change ac electric energy at one voltage level into ac electric energy at another voltage level through the action of a magnetic filed .It consists of two or more coils of wire wrapped a common ferromagnetic core. These coils are (usually) not directly connected. The only connection between the coils is the common magnetic flux present within the core.One of the transformer windings is connected to a source of ac electric power, and the second (and perhaps third) transformer winding supplies electric power to loads. The transformer winding connected to the power source is called the primary winding or input winding, and the winding connected to the loads is called the secondary winding or output winding. If there is a third winding on the transformer, it is called the tertiary winding.Power transformers are constructed on one of two types of cores. One type of construction consists of a simple rectangular laminated piece of steel with the transformer windings wrapped around two sides of the rectangle. This type of construction is known as core form. The other type consists of a three-legged laminated core with the windings wrapped around the center leg. This type of construction is known as shell form. In either case, the1外文翻译core is constructed of thin laminations electrically isolated from each other in order to reduce eddy currents to a minimum.Power transformers are given a variety of different names, depending on their use in power systems. A transformer connected to the output of a generator and used to step its voltage up to transmission levels is sometimes called a unit transformer. The transformer at the other end of the transmission line, which steps the voltage down from transmission levels to distribution levels, is called a substation transformer. Finally, the transformer that takes the distribution voltage and steps it down to the final voltage at which the power is actually used is called a distribution transformer. All these devices are essentially the same the only difference among them is their intended use.In addition to the various power transformers, two special-purpose transformers are used with electric machinery and power systems. The first of these special transformers is a device specially designed to sample a high voltage and produce a low secondary voltage directly proportional to it, Such a transformer is called a potential transformer. A power transformer also produces a secondary voltage directly proportional to its primary voltage the difference between a potential transformer and a power transformer is that the potential transformer is designed to handle only a very small current. The second type of special transformer is a device2外文翻译designed to provide a secondary current much small than but directly proportional to its primary current. This device is called a current transformerThe ideal transformer without loss of energy, so have a 100% efficiency. In reality, the efficiency of power transformer reaches 98%, But small transformer loss will be more serious, and they may be less than 85% of efficiency. The energy loss from transformer in these phenomena: (in a coil of narrative, conductive are called "core"The current through the winding resistance, thermal conductive (current generated when the heat to higher, the human body to feel energy losses caused to). And other kinds of loss, this loss not from the core transformer.Eddy: the magnetic loss to generate electricity, iron loop back into heat energy and loss caused to the outside world. The core of don't cut into thin can reduce the loss.Magnetism loss: all are not both senders coils magnetic field lines are receiving causes energy drain.Hysteresis: core lagged effect of magnetic field changes that every cause loss of energy. This depends on the size of the loss of the core materials.Alternating magnetic field strength loss: that wire, iron and near the electromagnetic force between the metal forming and3外文翻译changing the vibration and energy drain.Magnetostrictive: the magnetic field that appear alternately core.If the core material susceptible to expansion effect of friction between the molecules, will lead to loss of energy.Cooling equipment: large transformer with cooling fan with general of water pump, or the radiator. These devices have been using energy generally count the energy loss of transformer.The overhead three phase power transmission line is the main energy corridor in a power system. One might assume that the circuit model would be trivial (ideal conductors), but three different phenomena produce effects that can not reasonably be ignored. In order of importance, they are the series voltages induced by the magnetic fields surrounding the conductors, the shunt displacement currents resulting from the electric fields between conductors，and the ohmic resistance of the conductor material. A forth，and minor, effect is the leakage conduction current that flows through contamination films on the insulators．The overhead neutrals of a typical overhead power transmission line are electrically in contact with the tower and therefore grounded, They primarily exists to provide lightning shielding for the phase conductors and also to carry zero sequence and harmonic currents that help to maintain balanced sinusoidal voltages. They are usually steel or aluminum and are small4外文翻译(diameter about lcm)．The phase conductors are much larger (diameter about 5cm), and are typically stranded a1uminum surrounding a stranded steel cable (for increased tensile strength). sometimes more than one (a "bundle") comprise a phase．A11 are bare (no insulating covering) for heat dissipation reasons; the phase conductors are insulated from each other and the tower by suspension from insulator strings.5外文翻译变压器变压器是通过磁场作用将交流电从某一电压等级转换至另一个电压级别的设备。
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Transformer变压器One of the most valuable apparatus in electric power system is the transformer, for it enables us to utilize different voltage levels across the system for the most economical value. Generation of power at the synchronous machine level is no rmally at a relatively low voltage，which is most desirable economically．Stepping up of this generated voltage to high voltage，extra-high voltage or even to ultra-high voltage is done through power transformers to suit the power transmission requirement to minimize losses and increase the transmission capacity of the lines．This transmission voltage level is then stepped down in many stages for distribution and utilization purposes．电力系统中的最有价值之一是器具的变压器，它使我们能够利用不同电压等级，整个系统的最经济的值。
通常在较低功率在同步计算机级别的一代是voltage，which，是最理想的economically．Stepping 高voltage，extra 高电压该生成电压或甚至超高电压通过以适应电力传输的要求，尽量减少损失的电力变压器和增加lines．This 输电电压等级的输电量然后走在很多阶段的分布和利用的目的最有价值的一个装置在电力系统变压器,因为它使我们能够利用不同系统电压水平在最经济的价值。
一代的电力水平同步机通常以较低的电压,这是最理想的economically.Stepping这产生电压高压、超高压甚至是通过高压电源变压器适应电力传动要求减少损失,提高传输容量的lines.This传输电压水平就下来了许多阶段,分配和使用目的。
A transformer is a static device for transferring electric energy from one circuit to another electromagnetically，that is，by induction instead of by conduction．Its usual function is to transfer energy between circuits of different voltage．A transformer has a magnetic core on which there are two or more windings．These windings are insulated from each other and from ground．In autotransformers，however，the windings are connected together．The assembly of core and coils is normally insulated and cooled by immersion in mineral oil or other suitable liquid within an enclosing tank．Connection to the windings is by means of insulating bushings，usually through the cover.变压器是一个静态的装置电能量转移到另一个排列从一个电路,通过诱导而不是conduction.Its通常以换乘功能电路voltage.A间能量不同变压器磁芯上有一个有两个或两个以上绕组windings.These彼此隔离和ground.In autotransformers,然而,绕组连接组装的核心和线圈手工相结合,通常是由沉浸在保温和冷却液矿物油或其他适合在一个附上的tank.Connection绕组通过绝缘衬套,通常是通过封面。
变压器是核心的将电能从一个电路转移到另一个electromagnetically，that is，by 感应而不是核心的，由conduction．Its 常用函数的静态装置是核心的不同的voltage．A变压器电路之间传输能量已磁芯的有两个或更多的windings．These 绕组彼此隔离从ground．In autotransformers，however，the 绕组连接的together．The 大会和是核心的线圈通常是核心的绝缘和冷浸于矿物油中或其他合适的液体内封闭tank．Connection 在绕组绝缘盖通过bushings，usually 的手段。
The “ratio of transformation” is determined by the rel ative number of turns in each of he windings．This is known as the “turn ratio” and it is the ratio of the no-load voltages．When the unit is carrying load, the ratio of the actual voltages is slightly different because of the drop caused by the flow of 1oad current through the impedance of the transformer windings．At rated load, this drop is known as the "voltage regulation". The amount of voltage drop varies with the power factor of the output even when the kilovolt-amperes remain constant．Practically all power transformers and many distribution transformers have taps in one or more windings for changing the turn ratio．Changing the ratio is desirable for two reasons to compensate for varying voltage drop in the system and to assure that the transformer operates as nearly as possible at the correct core density．For the latter purpose, the taps should be in the winding subject to the voltage variation. De-energized tap changers are used when it is expected that the ratio will need to be changed only infrequently, because of load growth or some seasonal change．The desired tap is selected by means of a ratio adjuster(no load taps)．Load tap changer(LTC)is used when changes in ratio may be frequent or when it is undesirable to de-energize the transformer to change a tap．It seldom makes much difference to the user which winding or windings are tapped；therefore，the choice is usually made by the designer on the basis of cost and good design. Both winding current andvoltage must be considered when applying LTC equipment．High voltage and high current applications require special considerations to arrive at an optimum location for the LTC equipment．Step down units usually have LTC in the low-voltage winding and de-energized taps in the high voltage winding．"转型的比率"是由他每圈相对数决定的windings．This 称为"转率"，这是空载voltages．When 股的比例承载负荷，因为下降1oad 通过的阻抗变压器windings．At 额定负载电流的流动引起的实际电压的比例略有不同这滴被称为"电压调节"。
即使当千伏安培保持所有电源变压器和许多配电变压器有水龙头的一个或多个绕组更改比率是可取的原因有两个补偿系统中变电压降，并向保证变压器操作正确核心density．For，后者的目的在尽可能接近的转ratio．Changing constant．Practically 的电压降量随输出的功率因素水龙头应在电压变清盘。
切断调压分接开关时预期比例将需要更改只有很少，因为负荷增长的使用或一些季节性的change．The 需要选择了水龙头比调节器(无负荷水龙头）的方式时比率的更改可能会频繁, 而使用．Load 分接开关（LTC）时，是不可取de-energize 更改很少tap．It 变压器多大差别，用户或其中缠绕或绕组用tapped；therefore，the 选择通常是由设计器成本和好的设计的基础上作出的。