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1、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
2、 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 linesThis transmission v
3、oltage 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
4、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 induc
5、tion 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 conne
6、cted togethe rThe 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
7、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wi
8、ndings . These 绕组彼止匕隔离从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 “ ratioof transformation is "determined by the relative number of turns in voltages. When the unit is carrying load, th
9、e ratio of the actual voltages is slightly different because of the drop caused by the flow of load 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 outpu
10、t even when the kilovolt-amperes remain constan teach of he windings. This is known as the“turn ratio”and it is the raoacbf the noPractically 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
11、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 dens ityFor the latter purpose, the taps should be in the winding subject to the voltage variation. De-energized tap changers are used when it is exp
12、ected 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 tran
13、sformer 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 cu
14、rrent 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 windin g"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
15、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 Changingconstant 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
16、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。绕组电流和电压必须考虑当应用 LTC equipment High 电压和高当前的应用程序需要特殊的注意事项,到达最佳位置为单位下来LTC equipment Step 通常会 LTC 中低压绕组和断电丝锥在高电压 winding “比转变”是由相关的圈数他windings.This 在每个被称为“转比率”以
17、及它是空的比例voltages.When单位带负荷、粮经比实际电压下降的略有不同,因为 造成1 oad流动的电流通过阻抗变压器的额定载荷的 windings.At,这滴被称为“电 压调节” 。电压降的数量随输出的功率因数即使kilovolt-amperes 保持不变。几乎所有开关电源变压器、 配电变压器有许多水龙头在一个或多个线圈来改变这一比例将ratio.Changing 是可取的 ,有两个原因来补偿系统中不同电压降,以确保变压器运行正像可能正确的核心 density.For后者目的、水龙头应该在绕组的电压变化主题。不带电更换时用自来水预计比例将需要改变,只是偶尔 ,因为负荷增长或一些季节性
18、选择所需的龙头 ;通过比例调节器(无负荷水龙头).Load 分流器(等),是用来改变时可以在比频繁或心甘情愿地德活力变压器以改变一个tap.It很少会造成大的差别用户绕组卷绕或轻,所以 ,选择是通常由设计师基础上的成本和好的设计。 两个绕组电流和电压时必须考虑应用等equipment.High 电压和大电流应用需要特别考虑到一个最佳位置,为等equipment.Step单位通常有疗效下在低 压线圈绕组和不带电水龙头在高压绕组。When energy is to be transferred between two circuits of nearly the same voltage The
19、use of autotransformers affords cost savings over two-winding unit sThe nearer the voltages are to each other, the smaller will be the autotransformer per kilovolt-ampere of output , and the greater the saving s The simplicity of phasing out systems has increased its us eMost autotransformers are Y-
20、connecte,dand it has been a standard American practice to add a low capacity, delta winding This is frequently referred to as a“ delta te rtIitasryprimar“y purpose has been to provide an internalpath for the third harmonic currents (required for excitation) , thus reducing those currents on the powe
21、r system It also helps to stabilize the neutral and to ground the system better In recent years, the use of shielded telephone cable has reduced the requirements for the delta tertiary. Because an autotransformer does not afford electrical separation between the two circuits, disturbances originatin
22、g on one circuit can be communicated to the other This difficulty is minimized by solidly grounding the neutral of the autotransformer. Solidly grounding the neutral , however, causes(amongother things)current of short-circuit magnitude to flow through the delta-connected tertiary winding during gro
23、und faults on either system. Autotransformers are not inherently self-protecting and, therefore, all windings must be examined for mechanical strength as applied to the system where they will be used . Tertiaries are normally 35 of the physical size of the largest winding of the autotransformer, unl
24、ess otherwise specified by the user.当能量将会转移到在两个电路 voltage.The 几乎一模一样的使用提供了autotransformers 节约成本 two-winding units.The 离电压是对方,较小的将是每kilovolt-ampere autotransformer 输出 ,越简单的 savings.The 淘汰系统是提高 autotransformers四use.Most,这是个标准的美国做法添加一个低容量、三角洲 winding.This 经常被称为一个“增量高等教育“牵引 ,主要目的是提供一个内部路径为第三谐波电流(要求励磁),从
25、而减少那些电流电源系统,也有助于稳定中性及地面系统better.In近年来,使用屏蔽电话电缆具有降低了要求高等职业学校教育。伊洛瓦底三角洲因为一个autotransformer不负担两个电路电气脱节、干扰来源于 一个电路能沟通的困难是减少工序的扎实的 autotransformer接地中立。坚定接地 中性的,然而,使(还有其他的议题)短路电流的大小delta-connected流到地面故障 时,在第三绕组或系统。Autotransformers并非内在自我,因此必须查看所有绕组机 械强度作为应用系统在哪里他们将被用到。Tertiaries通常是35%的物理尺寸最大 的绕组中的autotrans
26、former除另有规定外,由用户。当能量是两个几乎相同 voltage The 使用的耦电路之间传输提供节省成本超过双绕组units The 靠近,电压是彼此,就越小自耦变压器每千伏安培的较大的 output, and savings The 简单的逐步淘汰系统增加了其use Most 耦是 Yconnected, and 已添加低容量的标准美国实践winding This 通常称为"三角专上 " Its 的主要目的已提供内部路径 (需要励磁) 的第三个谐波电流, thus 减 少这些电源system It 上的电流也有助于稳定中性和地面的系统better In 最近 ye
27、ars, the 使用屏蔽电话电缆的三角洲减少了高等教育的三角洲的要求。因为自耦变压器不起两个电路之间的电分离,可以传达一个电路上原产的扰动,other This ,困难最小化通过扎扎实实地接地的自耦变压器中性。扎扎实实地接地neutral, however,原因(除其他外)电流的短路三角洲连接专上缠绕在任一系统接地故障期 间 内 流动 的 严重程度 。 耦本来 就不 self-protecting 和 therefore, all 绕组必须审查的机械强度,适用于使用场合的系统。 Tertiaries 通 常是35 of 的物理大小的最大清的自耦变压器,除非另有指定的用户。The bulk o
28、f a11 transformers, except for large extra-high voltage(EHV)and distribution units are three-phase units In the early days of the industry , It was almost universal practice in the United States to use three single-phase unitsconnected in a three-phase bank Insulation clearances and shipping limitat
29、ions for certain large EHV units now require this design. The distribution systems serve mainly single-phase loads in residential areas and are served from single-phase transformers;.大部分的大型超高压(超高压)和配电设备是在早期工业的三相 units.是在美国使用连接三相bank. Insulation间隙中的三个单相单位几乎普遍做法和运输条件的某些大型超高压单位现在需要此design. The分布系统服务主要是
30、单相负荷在住宅区和服务的单相transformers. a11 transformers except各式各样的变压器的体积,除了大型超高压(超高压)、销售单位三相单位。在 早期的产业,它几乎是普遍的实践在美国使用三个单相单位连接在一个三相 bank.Insulation间隙和运输限制某些大型超高压单位现在需要这个设计为单相负 荷分配系统的主要在居民区和供应从单相变压器。Selection and Cooling of Power Transformer选择和冷却的电力变压器选择与电力变压器冷却The selection of the transformer can have a major
31、impact on the cost a substation, since the transformer represents the major cost itemNameplate rating is only a guide to transformer application, and should only be used as a first step in the selection process. The transformer is available as a self-cooled unit, or it can be purchased with addition
32、al steps of forced cooling that use fan or fans and oil pumps. Transformer ratings can be increased from 2% to 66% by the addition of fans and pumps The nameplate rating is based on a continuous load producing a 55 to 65 c conductor temperature rise over ambient. Since many transformers do not carry
33、 continuous loads, advantage can be gained from the thermal time lag to carry higher peak loads without exceeding the temperature limits .Transformer ratings are based on the assumption that only an extremely slow deterioration of insulation will take place with normal operation. A substantial incre
34、ase in rating can be achieved by accelerating the loss of insulation life. This increase in rating might approach 20阴 for an hour or two, and approximately 120 for 24 hours For substations that are designed to carry full load under the outage of any one transformer, a high emergency rating for a 24-
35、hour period (e.g. until the failed unit can be replaced) could mean the selection of smaller transformers and a substantial saving in substation co stThe selection of the transformer should involve a careful evaluation of a number of other factors:变压器的选择带来了极大的负面影响一个变电站的成本,因为变压器代表主要成本item.Nameplate评级
36、是唯一指南在变压器应用,只应作为第一步选择过程。变压器是可作为一个self-cooled 单位 ,也可以购买额外的步骤,使用强迫冷却风扇或球迷和石油pumps.Transformer评级可以从25%上升到66%增加的球迷和水泵铭牌评级是基于一个持续负荷55生产到65环境温度上升的导体。由于许多变压器不带连续荷载,可以得到优势进行热滞后时间没有超过峰值负荷较高的温度范围。 变压器评级建立在假定只有一个极慢的恶化将发生与普通保温措施大幅度增加评级可以达到加速损失的绝缘life.This 评级可能已经接近200%增加一两个小时,而大名有120%,24 hours.For变电站用于承受负荷的任何一个变
37、压器的中断 ,高紧急等级来24 小时内(例如 ,直到失败单元可以代替)可能意味着选择较小的变压器以及大幅度节省变电站成本。变压器的选择应该包括仔细评估其他一些因素:变压器的选择可以在成本上,变压器代表成本item Nameplate 评级的主要是不仅 指南变压器 application , and 只 用 于作为第一步 选 择 过程 中 的 substation, since产生重大影响。变压器是可用的因为自冷的unit, or,它可以购买的强制冷却使用风扇或风扇和油pumps Transformer 评级的额外步骤可以从 25 由增加到 66 的球迷和 pumps The 铭牌评级基于对环境
38、产生55 至 65 导体温升连续负载。 由于许多变压器不带连续loads, advantage可以获得热滞后时间不超过温度限制的情况下进行更高的峰值负载。 变压器评级基于假设只有极其缓慢恶化的绝缘的进行大量正常operation A 评级的增加可以实现通过加速的绝缘life This 增加评级中的损失可能接近每小时200for或两个和约 120 for 24 hours For 变电站,为了把满负载下的任何一个变压器停电紧急高评级的 24 小时内 (例如直到失败可以更换设备) 可能意味着更小的变压器的选择,并大幅度的变压器选择保存在变电站花费了。 应涉及慎重评估的一些其他因素是:(1)Impe
39、dances should be selected considering their effect on short-circuit duties and low-side breaker ratings both for initial and future station developments In addition , impedance is important to achieve a proper load division in the parallel operation of transformers.(2)No load tap ranges should be se
40、lected to provide an adequatelow-side bus voltage.(3)If the high-side or low-side voltages vary over a wide range during the load cycle, it may be necessaryto provide bus regulation The actual regulation can be calculated using the system and load characteristics If regulating equipment is needed, i
41、t may be desirable to provide it in the transformer by using load tap changer(LTC) equipment. If the need for bus regulation is not presently evident, but may be required in the future, it may be economical to leave space in the station for future regulators, and buy transformers without LTC equipme
42、nt.(1)阻抗选择应考虑他们的职责和low-side 影响断路器评分短路的初始和未来都站developments生止匕外,阻抗是很重要的,取得适当的平行作业负荷的分裂变压器的 . .(2)不负载范围应选择水龙头提供适当的low-side 母线电压。(3)如果高端或low-side 电压范围在不同载荷循环期间,可能有必要提供汽车regulation.The实际规定可以计算系统和负载characteristics调节设备是必需的它可能需要它提供在变压器采用负载分流器(等)设备。如果需要汽车目前规定不明显 ,但可能需要在未来,它可能是经济在车站离开空间为未来的管理者,而且买变压器等设备没有。()
43、1 考 虑 到 对 他 们 影 响 短 路 职 责 和 低 边 断 路 器 评 级 最 初 和 未 来 站 developments In addition, impedance是重要实现的变压器并联运行一个恰当的 负载司应选择阻抗。 ( 2) 应提供足够低边母线电压选择没有加载水龙头范围。 () 3 如果高边或偏低电压随负载周期期间的范围广泛,可能需要提供可以使用系统计算巴士 regulation The 实际监管和调节设备的负载characteristics If是 needed, it 可能需要通过使用负载水龙头 changer(LTC) 设备提供它的变压 器。 如果总线管需要不是目前是
44、显而易见的但可能需要在未来, 它可能为将来的 监管者,站在离开空间,买不需LTC 设备变压器经济。A great many transformers, including all the large ones and all the high voltage ones are immersed in mineral oil which serves the double purpose of cooling and insulating the windings. Small transformers have enough tank surface to radiate a11 the he
45、at caused by their losses without exceeding the permissible temperature r isAes size increases, the losses increase faster than the tank surface which soon becomes inadequate Various methods have been developed to get the heat out of the tank more effectively Large power transformer being built toda
46、y are commonly of the forced-oil-cooled type In this design the oil is pumped both through the external cooling devices(air or water heat-exchangers)andthrough internal channels that are located nearest the points where the heat is generat edThus the transfer of heat to and from the oil is far more
47、effective than in the plain self-cooled or fan-cooled unit where the oil is allowed to circulate by convection. When oil-to-air heat exchanger(a group fans on each radiator)is use,d this cooling type is designated as type of FOA While oil-to-water heat exchanger is use,d it is called FOW 许多变压器,包括所有的
48、大的和所有高电压的沉浸在矿物油的双重目的服务的冷却和绝缘绕。 小型变压器有足够的容器表面辐射热量减去所引起的损失而不超过允许的温度rise.As 尺寸增加,损失增加的速度比坦克表面,很快就变成inadequate.Various方法已经发展到过热的坦克正在建造更effectively.Large电力变压器今天的 type.In 一般 forced-oil-cooled 这个设计中被抽同时通过外部冷却设备(空气或水密闭式畜禽)和通过内部通道,通道位于在最近的点generated.ThusB 量转移的热量和从石油远比在平原更有效self-cooled或fan-cooled单元中时,其石油是允许流通
49、的对流。 当 oil-to-air 换热器 (一群球迷在每个散热器)使用 ,这种冷却式被指定为类型的 FOA.While oil-to-water 换热器使用,它被称为FOW。伟大多台变压器, 包括所有大型的和所有高电压的沉浸在矿物油的冷却和绝缘绕组的双重目的。小变压器有足够罐表面辐射的 a11 引起他们的损失不超过允许的温度rise As 大小increases, the 损失增加得更快,很快就将成为inadequate Various 方法的油箱表面的热已开发可以得到的罐内热今天正在兴建更多 effectively Large 电力变压器是常用的强迫油冷type In 这油抽水都通过外部冷
50、却设备 (空气或水热交换器) 的设计和通过内部渠道位于最近的热量在哪里generated Thus 的点的传热和油是比在油流通获对流的普通自冷或风扇冷却的装置有效得多。 当油 -空气换热器 (每个散热器组风扇) 是 used, this 冷 却类型被指定为 FOA While 油-水换热器的类型是used, it 被称为 FOWFor applications where any liquid, even a nonflammable one, is objectionable, the dry-type transformer is used The ventilated dry-type
51、unit is cooled by a continuous natural draft of air and consequently is not suitable for locations where the air is wet or dirty. For these locations a completely enclosed un,itthe sealed dry-type, is available, having a core-and-coil in a tank that is sealed and filled with an insulating gas. Dry-t
52、ype transformers are completely nonflammabl,e using organic material such as epoxy resin.为应用程序的任何 liquid , even 不可燃 one, is objectionable ,the 型干式变压器在哪里used The 通风的干式单位由连续的自然通风的空气冷却和因此不适合那里的空气是湿或肮脏的位置。 为这些位置完全封闭的 unit , the 密封干 type , is available ,having 核心 -和线圈被密封和装满绝缘气体的容器。 干式变压器完全是 nonflammable
53、, using 有机材料如环氧树脂。可应用在任何液体,甚至是一种难燃的人,是令人讨厌的,变压器通风产品结构设计和冷却市区单位由连续的自然通风的空气,因此不适合场所空气潮湿或脏。 为这些位置完全封闭的单位、 密封结构,是可行的,有一个 core-and-coil 密封在一个鱼缸,并充满了一种绝缘气体。变压器结构设计是完全不可燃,使用环氧树脂有机物质。Circuit Breaks 电路符 电路打破Within a few years of the introduction of the fuse, the growing electrical industry startedlooking for
54、 an alternative method of providing protection for electric circuits They wanted a device that would not be destroyed by its operation , that could simply be reset to restore power, and that could also be used as a means of switching for the circuit Out of this development work came the circuit brea
55、ker which is an electromechanical device The circuit breaker is defined as a device designed to open and close a circuit by non-automatic means and to open the circuit automatically on a predetermined over-current without injure to itself when properly applied within its rating.As with other equipme
56、nt, circuit breakers are divided into those rated for 1 000 volts and less and those rated for more than 1000 volt s Low-voltage circuit breakers were also divided into two distinct categories , molded-case and power types However, in the past few years the distinction between these two types has be
57、come less clea-cut as a new type of encased breaker are universally operated in air, so it is not necessary to designate them as air circuit breakers as this understood Medium and high voltage breakers, on the other hand, use mediums other than air in which to open the circuit and therefore must be
58、designated as being air, gas, and so on在短短几年内引进的保险丝,日益扩大的电气工业开始寻找一个替代方法的电力 circuits.They 想要提供保护装置,不会破坏其运行,那可能只是被重置为恢复供电,也可以使用的一种手段circuit.Out 切换的开发工作的电路breaker.which来为机电一体化装置,断路器被定义为一种装置,用来实现一个电路开启和关闭非自动化手段和打开电路自动上预定过流没有伤害到其自身在适当的应用其信用评级。与其他设备、 断路器分为 1 000 伏被评为越 来越被评为超过 1000 volts.Low-voltage 断路器也被分为两大类,types.However molded-casef力量,在过 去几年中区别这两种类型已变得更有clea-cut 作为一种新型被普遍地在空气断路器操作,所以没有必要指定
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