使用触发方法对固定间隙中真空断路器电弧进行调查

1、Investigation of the Arc of a Vacuum Circuit Breaker in a fixed Gap using the Triggering method.使用触发方法对固定间隙中真空断路器的电弧进行调查。Abstract摘要When the contacts of a Vacuum circuit breaker (VCB) with current flowing through it, is separated, an arc is generated.当电流流过真空断路器（VCB）的触点分离时，产生电弧。The Arc is usually supp

2、orted by ionized gas or ionized metal vapour derived form the metal contact. 电弧通常由电离气体或从金属接触形成的离子化金属蒸气形成的。This arc is an essential component of the interrupting process and capability of the Vacuum circuit breaker. 该电弧是真空断路器的中断过程和能力的重要组成部分。The object of this paper is to trigger, record, observe and

3、analyze the dynamic image of the Vacuum arc when it ignites in a short gap and at a low voltage.本文的目的是触发，记录，观察和分析真空电弧在短间隙和低电压下点燃的动态图像。A CMOS high speed digital camera will be used to record the images of the arc. CMOS高速数码相机将用于记录电弧图像。The characteristics of the arc in its diffused and constricted stat

4、e, the degree of changes between the two states, and the direct relationship between the voltage and current will also be observed. 将观察电弧在扩散和收缩两种状态之间的变化程度以及电压和电流之间的直接关系The life time of the Vacuum arc will be 10ms.真空电弧的寿命为10ms。1 Introduction 引入VCB is one of the simplest circuit breakers. VCB是最简单的断路器之

5、一。Its design and construction consist of one fixed pole and one moveable contact placed in a vacuum vessel. 其设计和结构由放置在真空容器中的一个固定杆和一个可动触头组成。Its application has now been widely accepted in electric power system, especially in the medium voltage region. 其应用现已广泛接受电力系统，特别是在中压区域。Today it has largely repla

6、ced other arc-type interrupting devices and its main advantages include, its compact design, maintenance free, long life operation, has a very good environmental compatibility and its excellent interruption and dielectric recovery characteristics which can interrupt the high frequency current result

7、ing from the arc instability. 今天它已经在很大程度上取代了其他电弧型中断装置，其主要优点包括紧凑型设计，免维护，使用寿命长，具有很好的环境兼容性，优异的中断和介电恢复特性（可中断由电弧不稳定引起的高频电流）The characteristic of the vacuum arc have been of paramount importance for the successful interruption of short Circuit currents in medium voltage circuits. 真空电弧的特性对于中压短路电流的成功中断至关重要。

8、The arc exits in two forms, the diffused and constrict state.电弧以两种形式出现，即扩散和收缩状态。At low currents, up to 10 kA, the arc burns in diffused mode, so that the breakers contacts erosion and heating is acceptable. 从低电流到10 kA，电弧以扩散模式燃烧，使断路器接触腐蚀和温升在允许范围。But currents greater than 10 kA, the constriction of th

9、e arc caused by energy supplied to the Vacuum contact making it difficult for the gap to extinguish the arc at the instant of Current zero. 但是大于10 kA的电流，由于提供给真空接触器的能量引起的电弧的收缩使得间隙在电流零点瞬间熄灭电弧是困难的。The breaking capacity and reliability of interrupters depend greatly on the controlling of the vacuum arc.

10、 断路器的断路能力和可靠性在很大程度上取决于真空电弧的控制。Several researches have been carried out recently on methods of controlling the characteristics of the arc to keep it in its diffused state in order to design new type interrupters for high-voltage and high current power distribution. 近来已经对控制电弧特性的方法进行了几项研究，保持其处于扩散状态以设计用

11、于高压和大电流配电的新型断路器。To record the image of the arc changing from constricted form into a diffused form and analysis its characteristics, an experimental setup and a mathematic model of vacuum arc was used. 为了记录从收缩形式变化为弧形的弧的图像并分析其特征，使用了真空电弧的实验装置和数学模型。The recorded images and the mathematical model theory

12、of controlling the vacuum arc are analyzed and can be used to improve the quality and reliability of vacuum circuit interrupters. 通过分析记录图像和控制真空电弧的数学模型理论，以提高真空断路器的质量和可靠性。2.Experimental set-up 实验装置The circuit diagram of the experiment is shown in Fig.1; 实验电路图如图1所示。While Fig.2 shows Physical arrangemen

13、t of the equipment set-up in the experiment. 而图2显示了实验中设备设置的物理布置。The list of equipment consists of: 设备清单包括：1. Ultra high Vacuum test champers with two glass windows for Arc observation. 超高真空试验箱，带有两个玻璃窗用于电弧观察。2. Capacitor bank C0 电容器组3. isolation transformer 隔离变压器4. Mechanical pump 机械泵5. Wave scope 示波

14、器6. Inductor Lo 电感器The Mechanical pump evacuates the vacuum in the champers of any impurities and moisture to a vacuum level of less than6.66Pa. 机械泵将所有杂质和水分中的真空抽真空至小于6.66PaThe Co supplies a high arc current through L0 at a frequency of 50Hz to the contact gap. Co通过L0以50Hz的频率向接触间隙提供高电弧电流。The triggeri

15、ng pole placed at the centre of the hole of diameter 2mm in the cathode ignites the arc. 放置在阴极直径2mm的中心的触发极会点燃电弧。The contacts and electrode were isolated from both the chamber and ground. 触点和电极从腔室和地面分离。The current transformer CT and potential transformer PT were used to observe and measured the V-I c

16、haracteristic of vacuum arc. 电流互感器CT和电压互感器PT用于观察和测量真空电弧的V-I特性。The system used for recording the arc images is shown in Fig.4。用于记录电弧图像的系统如图4所示。The system is made up of: 系统由以下几部分组成：1. A vacuum arc, 真空电弧2. An Optical system (including filters and convex), 光学系统（包括滤光片和凸面）， 3. An Image Capture tools (incl

17、uding CMOS camera and A/D Converter) 图像捕获工具（包括CMOS摄像头和A / D转换器）4. An Image data transfer and storage / system interface to the wave scope and CRT 图像数据传输和存储/系统接口到波段和CRT5. A Voltage and current waveform analyzer 电压和电流波形分析仪6. A CRT CRT(“阴极射线显像管”，是一种使用阴极射线管（Cathode Ray Tube）的显示器。主要有五部分组成：电子枪（Electron Gu

18、n）、偏转线圈（Deflection coils）、荫罩(Shadow mask)、高压石墨电极和荧光粉涂层(Phosphor)及玻璃外壳。它是应用最广泛的显示器之一，CRT纯平显示器具有可视角度大、无坏点、色彩还原度高、色度均匀、可调节的多分辨率模式、响应时间极短等LCD显示器难以超过的优点，而且价格更便宜。)A. Triggering circuit 触发电路The triggering circuit is shown in Fig. 3.触发电路如图3所示It is made of two parts: 它由两部分构成1. High pulse voltage circuit, 高脉冲

19、电压电路2. High current circuit. 大电流电路。The high pulse voltage circuit which consists of R1, V1 and C1, produces a high pulse voltage to breakdown the vacuum dielectric; while the high current circuit made of R2, V2 and C2, provides successive energy enough to keep the vacuum arc burning. 由R1，V1和C1组成的高脉冲

20、电压电路产生高脉冲电压以击穿真空电介质;而由R2，V2和C2组成的大电流电路提供足够的能量来保持真空电弧燃烧。The high-voltage silicon stack SS provides a discharge path, and also insulates the high current circuit from the high pulse voltage circuit. 高压硅堆SS提供放电路径，并且使高电流电路与高脉冲电压电路绝缘。 Fig.6 shows the wave of the pulse voltage between A and B produced by

21、capacitor C1. 图6示出了由电容器C1产生的A和B之间的脉冲电压的波形。3. Observation of the Arc The camera and the triggering circuit were first set up respectively.首先设置相机和触发电路。The speed of the camera is set to 3.2secs at a resolution 1280128, while the life span of vacuum arc is about 10ms, so the camera is first triggered an

22、d then the arc ignited. 相机的速度设置为3.2秒，分辨率为1280128，而真空电弧的使用寿命约为10ms，因此应先触发相机，然后电弧点亮。400 images of the ignited arc was captured, the images showing the cathode spots movement, transition of vacuum arc from constriction to diffusion state and anode spots movement etc. 拍摄了400个点火电弧图像，显示阴极点运动，真空电弧从收缩转变到扩散状

23、态，阳极点运动等。Vacuum Arc Analysis Mathematical Model Fig.5 shows a model of the experiment set-up to observe the vacuum arc in a vacuum circuit breaker. 真空电弧分析 - 数学模型图5为在真空断路器中观察真空电弧的实验设置模型。The following assumptions are made: 做出以下假设：1. C1 the capacitance between anode and shield阳极和屏蔽间的电容2. C2 the capacit

24、ance between cathode and shield阴极和屏蔽间的电容3. R1 the resistance between anode and shield 阳极和屏蔽间的电阻4. R2 the resistance between cathode and shield 阴极和屏蔽间的电阻5. U0 the voltage between anode and cathode阳极和阴极之间的电压6. U1 the voltage between anode and shield 阳极和屏蔽之间的电压7. U2 the voltage between cathode and shie

25、ld阴极和屏蔽之间的电压8. U4 the voltage between shield and ground屏蔽与地面之间的电压From fig 5 the voltage relation equation is given by: 从图5可以看出，电压关系式由下式给出：the arc does not only spread between the vacuum gap but also spreads to the space between the shields and the electrodes, the rate reaching the shield is more if

26、the current the of the vacuum arc is high, resulting in the presence of metal vapour in this space and since there is also a resistance between the electrode and the shield: 电弧不仅在真空间隙之间扩散，而且扩散到屏蔽和电极之间的空间，如果真空电弧的电流大，则达到屏蔽的速率更高，导致在此处存在金属蒸气，而且电极和屏蔽之间也有电阻：Formula 5 then becomes: 公式5然后变成：if the arc ignit

27、es only between the contact gap ,RI and R2 is negligible, that is no resistance exits between space and contact equation (1) and (3) becomes: 如果电弧仅在接触间隙之间点燃，则RI和R2是可以忽略的，他们之间没有电阻，则空间方程和接触方程（1）和（3）变为：But when the arc of the Vacuum Arc is large enough to cause metal vapour movement to the space betwee

28、n the electrode and the shield, the will be resistance between the space and the contact, the resistance is given by: 但是，当真空电弧的弧度足够大以使金属蒸汽移动到电极和屏蔽之间的空间时，空间和触点之间将产生电阻，电阻由下式给出：from equation 8 and 9 it can be seen that if the intensity of the arc is large then it will cause metal vapour movement to the

29、 space between the shield and the contact, and also the arc will constrict longer and strong enough to damage the surface of the breakers contact, so it is necessary to control the intensity of the arc and prevent it from constricting and keep it in a diffuse and stable arcing state. 从等式8和9可以看出，如果电弧

30、强度大，则会导致金属蒸汽在屏蔽和触点之间移动，并且电弧会收缩较长而足够强，破坏断路器的接触面，因此有必要控制电弧的强度，防止电弧被收缩并保持在漫反射稳定的电弧状态。Applying a magnetic field on a vacuum arc is an effective method of maintaining a diffuse arc even at high current in the Vacuum circuit breaker. 在真空电弧中施加磁场是在真空断路器中即使在高电流下仍保持漫反射电弧的有效方法。Many Manufacturers have used this

31、 method to design vacuum circuit breakers with stable and diffuse Arc at high voltage and current level. 许多制造商已经使用这种方法在高电压和电流水平设计具有稳定和漫反射电弧的真空断路器。Two methods, namely the AMF Axial Magnetic field and RMF Radial magnetic field are used to apply a magnetic field to the arc of the Vacuum Arc, ensuring t

32、hat there is less contact erosion and also improving the switching capacity of the interrupters 使用两种方法，即AMF轴向磁场和RMF径向磁场对真空电弧的磁场施加磁场，确保接触侵蚀较少，并且还提高断续器的开关容量4. Experimental Results 实验结论During the Experiments the following assumptions were made: 在实验期间，做出了以下假设：1. voltage of the capacitor C0 is set to 200

33、V. 电容器C0的电压设定为200V。2. The gap between the electrodes is about 8 mm. 电极之间的间隙约为8毫米。3.Optronis-Camracord High-speed camera Ca 1000, Max-Revolution=12801024, Max-sampling freq=200,000.Fps .Optronis-Camracord高速摄像头Ca 1000，最大公转= 12801024，最大采样频率= 200,000.FpsA. V-I Characteristics. 伏安特性The relationship betwe

34、en the peak voltage and Peak current a very important characteristic of the vacuum arc is indicated in Fig 6. 峰值电压和峰值电流之间的关系是真空电弧的一个非常重要的特性，如图6所示。It shows the voltage-current characteristic of vacuum arc at different length of the short gap. 不同长度短间隙的真空电弧的电压 - 电流特性如图所示。B. Images of vacuum arc 真空电弧图像D

35、uring the whole optical test process to observe the igniting of the arc at 10ms, 400 frames images of vacuum arc were recorded with a high speed CMOS Video camera the images are shown in Fig 7. 在整个光学测试过程中，在10ms观察电弧点火，用高速CMOS摄像机记录400帧真空电弧图像，图像如图7所示。These images show some characteristics of vacuum arc

36、. 这些图像显示出真空电弧的一些特征。It shows that the arc has five distinct stages: 这表明电弧有五个不同的阶段：1.The Initial stage of the arc: The arc immediately after the ignition-images 1 - 3. , this is at the point when the arc was triggered between the triggering electrode and the anode and resulting in the initial plasma b

37、etween the main gap anode and the cathode .弧的初始阶段：即刻点火图像1-3之后的电弧，这是触发电极和阳极之间电弧触发的时刻，在主间隙阳极与阴极之间产生初始等离子体。 2.Constricted stage 1: image 4-6 the arc just begin to get into its constriction stage and is yet to attain its max value, it begins to spread quickly from the cathode to the anode 收缩阶段1：图像4-6，弧开

38、始进入其收缩阶段，并且尚未达到其最大值，它开始从阴极迅速扩展到阳极3.The constrict stage: images 7-9 the constricted arc attains it max value and is strongest at the stage and can melt the anode contact and forms several spots on the surface. 收缩阶段：图像7-9，收缩电弧达到最大值，在阶段最强，可以熔化阳极接触并在表面形成几个点。4.The Diffuse stage: images 10-12 here the arc

39、 begins to quench and becomes weak and starts to die down and migrates to the outer space and breaks up into spots between the gaps. 漫射阶段：这里的图像10-12开始熄灭，变弱，开始死亡，并移动到外部空间，并分裂成间隙之间的斑点。5.Quenching Stageimages 13-15), this is when the arc beings to finally extinguish, the current of the Arc decreases qu

40、ickly and the intensity of the arc disappears at the surface of the anode. 熄灭阶段图像13-15），这是当电弧终于熄灭时，电弧电流迅速下降，电弧强度在阳极表面消失。The arc disintegrates into several light spots called cathode spots moving at high speed on the surface until it all finally disappears or extinguishes. 电弧分解成表面高速移动的称为阴极点，直到它们全部消失或

41、熄灭。5. Conclusion. 结论Understanding the behavior and the thermodynamics of the Vacuum arc of a VCB circuit breaker is very necessary to improve the performance, efficiency, design and the correct functioning of the interrupter. 了解VCB断路器真空电弧的行为和热力学对于提高断路器的性能，效率，设计和正确的功能是非常必要的。Generally there are three

42、methods to produce an arc in a vacuum namely, Draw Arc, inducing Arc and the triggering arc. 通常有三种在真空中产生电弧的方法，即绘制弧，诱导电弧和触发电弧。The triggering method was used in this paper to record the arc intensity, the constriction and diffusion changes in the arc.本文采用触发方法记录电弧强度，电弧中的收缩和扩散变化。About 400 images were collected at a speed of 4000fps and 1280 x 1024 pixel during the investigation.在调查期间以4000fps和12801024像素的速度收集了约400张图像。The investigation of the arc within a 10m