110kV降压变电所英文文献

英文文献Cirtcuit BreakersA circuit breaker is mechanical switching device capable of making,and breaking currents under normal circuit conditions and also making.carring for a specified time ,and mediujm in which circuit interruption is performed may be designated by a suitable prefix, for example,air-blastcircuit breaker,oil circuit breaker.The circuit breakers currently in use can be dlassified into the following categories according to the arc-quenching principles:air swetches oel ciryit breakers,minmum-oil circuit breakers,air-blast circuit breakers,the magenetic air circuit breakers,minimum-oil circuit breakers,aer-blast circuit breakers,the by voltage,insulation levelcurrent,interrupting capabilities,transient recovery coltage,interrupting tiome,and trip delay.The nameplate on a circuit breaker usually indicates:.The maximum steady-state current it can carry, 2. The maximum interrupting current,3. The maximum line voltage,4.The interrupting time in cycles, The interrupting time in may last form 3 to 8 cycles on a 60 Hz system. To interrubt large currents quickly, we have to ensure rapid cooling. High-speed interruption lunits the damage transmission lines and equipment and, equally important,it helps to mainmain the stability of the system whenever a contingency occurs. The main parts of a circuit breaker are usually:arc-quenching chamber (or interrupter with moving and fixed contacts) operating mechanism and supporting structures. Air Switches-With increasing currents and voltages, spring-action driving mechanisms were developed to reduce contact buring by faster-opening operation.Later,main contacts were fitted with arcing contacts of special material and shape,which opend after and closed before the main contacts.Further improvements of the air switch were the bursh-type contact with a wiping and cleaning function,the insulating barrier leading to arc chutes,and blowout coils with excellent arc-extinguishing properties.These features,as well as the horn gap contact,are still in use in low voltage as and de breakers. Oil Circuit Breaker Around 1900, in order to cope with the new requirement for “interrupting capacity”,AC switches were immersed in a tank of oil. Is very effective in quenching the arc and establishing the open break after current zero.Deion grids,oil-blast features,pressure-tight joints and vents,new operating mechanisims,and multiple interrupter were introucedover several decades to make the oil circuit breaker a reliable apparatus for system voltage up to 362Kv.Types and Construction of TransformerA transformer is a device that alternating current electric energy at one voltage level into alternating current electric energy at another voltage level through the action of a magnetic field.It consists of two or more coils wire wrapped around a common ferromagnetic core.These coils are (usually)not directly connected. The only connection between the coils is the common magnectic flux presen 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 souce is called the primary winding or input winding.and the winding connected to the loads is called the secondary winding or input winding.If there is a third winding on the transformer,it is called the tertiary winding.Power transformer 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 know as coreform .The other type consists of three-legged laminated core with the windings wrapped around the center leg .This type of construction is know as shell form.In either case,the core is constructed of thin laminations electrically isolated form each other in order in order to reduce eddy currents to a minimum.The primary and secondary windings in a physical transformer are wrapped one on top of the other with the low-voltage winding innermost.Such an arrangement severs two purposes: 1.It simplifies the problem of insulating the high- voltage winding from the core.2.It results in much less leakage flux than would be the two windings were separated by a distance on the core.Power transformer 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 transformer levels is sometimes called unit transformer. The transformer ai the other end of the transformer 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 is down to the final voltage ai 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 transformer, 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 device designed to provide a secondary current.much smaller than but directly proportional to its primary current.This device is called a current transformer.Lingting protectionThe thunder and lightning protects to connect the ground; Connect the ground to avoid the thunder the most important link of the technique, ignore is a shot thunder, respond the thunder of the thunder or other form, and avoid the thunder work most all of send into the earth the thunder electric current. Store the thunder energy to behave the type to build the , current technology to still reach to not arrive, and therefore have no the reasonable but good connect the ground equip to is impossible to speak about to defend the thunder.Therefore say the design, the construction is very high standard to connect the ground system is a heavy inside that defend thunders work it heavy. High electric potential that For long time, people have an illusion, and think that connect the ground electric resistance more small avoid the thunder result and then more like, quilt object that protect safety. Certainly the electric resistance is more the small is more quick, strike by lightning to reserve time more short, the risk is more small, electric voltage of its stride, get in touch with the the electric voltage produce the machine too the more the ?But, construction that the fulfillment proof of near and more than ten in the last yearses, with its say that connect the worth importance of ground electric resistance, not equal to say that connect the ground to equip more reasonable, importanceElectricity equipments, demand variety that nows city, there is lots of in a building inside not the congeniality connect the ground device, if avoid the thunder to connect the ground, electricity the safety to connect the ground, AC power the work to connect the ground, correspondence and calculator system to connect the ground, according to the fulfillment proof, totally use to connect the ground is an application most for extensive connect the local type. That A, the independence connect the ground: As above part for demand for speak ofing connecting the ground of, all distinguish to independently establish the own to connect the ground system, and this kind of connect the local type to call the independence to connect the ground. Its advantage is each system and cant result in the mutual interference, and this is particularly important to correspondences systems.But the adoption independence that network easily were strike by lightninged is bad, so besides have to defend to explode the dangerous environment requesting to must want the adoption the independence of avoid the thunder method generally not lay claim to the way to connect the ground. Two, totally use to connect the ground: Also call unify to connect the ground.The each system that it connect the ground the demand unifies to receive a connect the ground to equip top, or is originally each system of connect the ground device to pass the underground to perhaps and up link, make them the electricity for becoming of its to connect the ground to unify the ground net with metals conductor, like this of connect the local type is to totally use to connect the ground. it is current to use to connect the ground totally applied the most extensive connect the local type. Each system that Three, connect the ground 1:00: Method that connecting the ground line to receive to connect the same point or same metals flat surface of line of ground mother of each system is up, like this call connect the ground 1:00 method. connect 1:00 the ground method can resolve the etc. Electric potential to connect the ground line the problem, can therefore lower of each system can cancellation of top of interference fundamental for of interference degree, particularly is 50 HZ work signal to system, and connect the ground method on the engineering to get the extensive application therefore and 1:00. Four, the many point connect the ground:The ground line of connecting of each system adopt many pointses short on-line connect the local type, and call to much order to connect the ground. Five, mix with to connect the ground: Metals line that so- called admixture connect the ground to is at an each circuit board in equipments to connect, or related and a few equipmentses of signal electric circuits, with the most short line with the same of metals to link to connect the ground with the most short line and machine hull, then the equipments of many sets use respectively the same point top to receive the ground net. Six, the wreath form connect the ground to much used for the ground net, be connect the ground to round along building surroundings a shut to match the wreath. like this of connect the electric field that ground net can make the interface including distribute even, reduce the stride electric voltage to bane person, and also reduce the indoors while suffering strike by lightning, because of the ground electric potential the steps degree is big but produce the danger to counter-attack to equipments high pressure. Seven, the foundation connect the ground:Make use of the reinforcing bar in the building foundation, and press norm the request the conjunction to create of connect the ground to call the foundation to connect the ground.断路器空气压缩断路器是一种机械开关设备，能够在正常和特殊情况下开断电流（比如说短路电流）。例如空气断路器、油断路器，干扰电路的导体因该安全可靠的应用于其中，电流断路器按灭弧远离通常被分为如下等级：空气开关断路器、油断路器、少油断路器、压缩空气断路器、具有消磁性质的隔离开关、六氟化硫断路器和真空断路器。他们的参数有电压等级、绝缘等级、电流开断容量、开断时间的瞬时电压恢复和条炸事件。断路器的铭牌通常包括：1.最大可承受电流；2.最大中断电流；3.最大线路电压；4.中断周期数量。在60hHZ的系统中，中断可能持续3-至8个周期，为了快速中断达负荷电流，我们不得不确保它的持续冷却，、高速开断能限制对传输线路的损害，这一点是同等重要的它帮助系统在任何事故发生时维持稳定运行，断路器主要由操作机构、执行机构和灭弧室组成。 当有触发电流或者电压时，空气隔离开关的弹簧操作机构迅速动作以用来减少触点的烧损，主触点的特殊形状和使用材料完全适合电弧的接触，空气隔离开关更进一步的改进是由于灭胡贤泉的性能、绝缘隔板组成的灭弧罩、带灭弧功能的触头等这些特殊性质，所以仍被应用于低电压等级和直流断路器中。 多油断路器出现于1900前后，主要用来满足新斯的开断容量的要求，交流开关被浸入一个油缸之中，油在熄灭电弧和在电流过零时建立开断功能是十分有效，灭弧栅、喷油嘴、鸭梨锄头、新的操作机构和多种新的断路功能在近几十年引进使用多油断路器能够适应362kV。变压器的类型和结构变压器是一个通过磁场作用将一个交流电压值变成另一个电压值的设备。它由2条或更多的金属丝缠绕在一个核心磁铁上组成的。这些绕线（一般）不直接接触。绕线之间唯一的联系是它们共有的存在于磁芯的磁通量。 一组变压器绕组连接到一个交流电源上，同时第二组（或许第三组）变压器绕组作为电源提供给负载。连接到电源上的变压器绕组叫做一次绕组，或者输入绕组。连接负载的绕组叫做二次绕组或者输出绕组。如果电压器上有第三绕组，它叫做三次绕组。 电力变压器由一两种磁芯中的一种构成。一种构造是由一种简单的变压器绕组缠绕在矩形两边的矩形薄钢片组成。这种构造类型被认为是核心形式。另一种类型是由绕组缠绕在中心引脚的3引脚叠片铁心构成。这种构造类型贝壳形式。其中任意一种类型，磁心都是由排列整齐的彼此之间电气隔离的薄迭片构成