低压系统

Looks from the system communication effect, this system has a higher antijamming, the anti-signal weakens ability, the system can achieve a farther transmitting range, simultaneously because the communications system essential part SC1128 (Spread Spectrum / solution expand chip) is specially designed according to the domestic low power line characteristic, the performance price is high, these are all advantageous to the system's promotion.

从系统的通信效果来看，本系统有较高的抗干扰，抗信号衰减的能力，系统可达到较远的传输距离，同时由于通信系统的关键部件SC1128是根据国内低压电力线特性而专门设计的，性价比高，这些都有利于系统在做进一步的完善后在国内自动抄表行业内的推广。

Urban systems generally use a large number of low-pressure valve, and to environmental protection and development of energy-saving, that is, by the use of low pressure over the last steel valve towards environment-friendly plastic valve, balance valve, metal sealed butterfly valve and the center line butterfly valve seal transition, oil and gas to the pipeline of development projects, which in turn requires a large amount of flat gate valve and ball valve

2城建系统一般采用大量低压阀门，并且向环保型和节能型发展，即由过去使用的低压铁制闸阀逐步转向环保型的胶板阀、平衡阀、金属密封蝶阀及中线密封蝶阀过渡，输油、输气工程向管道化发展，这又需要大量的平板闸阀及球阀

When entering the diaphragm pressure on the top of the control room to the atmosphere or water by the downstream area of low pressure, the role of the bottom plate in the valve and the pressure below the diaphragm on the pressure value is greater than the top, so the main valve disc to the fully open position; when entering the diaphragm pressure above the control room can not water the lower reaches of the atmosphere or area of low pressure, the role of the diaphragm on the top of the pressure value is greater than the pressure below the value, so will the main valve pressure valve set to fully closed position; when the diaphragm pressure above the value of the control room at the entrance of the middle pressure and outlet pressure, the main valve in the regulator valve on the disk, and its regulation depends on the location of the needle-catheter system and adjustable valve guide of the role of joint control.

当阀门进入隔膜上方控制室内的压力水被排到大气或下游低压区时，作用在阀盘底部和隔膜下方的压力值就大于上方的压力值，所以将主阀阀盘推到完全开启的位置；当进入隔膜上方控制室内的压力水不能排到大气或下游低压区时，作用在隔膜上方的压力值就大于下方的压力值，所以就会把主阀阀盘压到完全关闭的位置；当隔膜上方控制室内的压力值处于入口压力与出口压力中间时，主阀阀盘就处于调节状态，其调节位置取决于导管系统中的针阀和可调导阀的联合控制作用。

When entering the diaphragm pressure on the top of the control room to the atmosphere or water by the downstream area of low pressure, the role of the bottom plate in the valve and the pressure below the diaphragm on the pressure value is greater than the top, so the main valve disc to the fully open position; when entering the diaphragm pressure above the control room can not water the lower reaches of the atmosphere or area of low pressure, the role of the diaphragm on the top of the pressure value is greater than the pressure below the value, so will the main valve pressure valve set to fully closed position; when the diaphragm pressure above the value of the control room at the entrance of the middle pressure and outlet pressure, the main valve in the regulator valve on the disk, and its regulation depends on the location of the needle-catheter system and adjustable valve guide of the role of joint control.

当进入隔膜上方控制室内的压力水被排到大气或下游低压区时，作用在阀盘底部和隔膜下方的压力值就大于上方的压力值，所以将主阀阀盘推到完全开启的位置；当进入隔膜上方控制室内的压力水不能排到大气或下游低压区时，作用在隔膜上方的压力值就大于下方的压力值，所以就会把主阀阀盘压到完全关闭的位置；当隔膜上方控制室内的压力值处于入口压力与出口压力中间时，主阀阀盘就处于调节状态，其调节位置取决于导管系统中的针阀和可调导阀的联合控制作用。

This apparatus has the functions of measuring, protecting, monitoring, controlling, and communication, it can replace the traditional apparatus of protecting and measuring, when combined with low-voltage frame breaker, they are base component of intelligent switchgears in low-voltage electric power system.

该装置集测量、保护、监控、通信等功能于一体，可替代传统的测量保护装置；与低压框架式断路器结合，可以构成低压配电系统智能化开关柜的基本电器元件。

Firstly, the realizable ways of signal detection and sample、 power circuit and the application of low-consumption model of MSP430 are discussed, by which the required function of current protection and voltage protection can be realized. Secondly, different protection algorithm based on micro-computer are discussed in this article, and from the virtues and defects of Fourier algorithm, an improved algorithm is put forward, and the importance of the improved algorithm is displaced. Thirdly, according to the national standard of GB/T18858 .3-2002, the principle of networklization of intelligence trip relay and how to realize it are mentioned. Lastly, using the current conditions, the test of precision is done. The experimental date present that the system is working well and can realize the real-time function of on-line detection.

首先在硬件设计上，对于信号检测、处理、电源电路、MSP430系列单片机的低功耗方式应用以及人机接口电路等问题提出了实现方法，基本实现了大范围电流、电压信号实时监控等功能；其次，本文还对当前各种微机保护算法进行了介绍，分析了傅立叶算法在实现智能脱扣器保护功能中的优缺点，并针对傅立叶算法中计算偏于复杂的问题对该算法进行了改进，提出了基于FFT的改进算法，通过算法的分析和比较，对改进算法的性能给出了评价；然后结合我国现场总线国家标准GB/T18858.3-2002讨论了DeviceNet现场总线在实现脱扣器网络化的原理，实现方法，论述了通讯接口电路的设计；最后利用现有条件，对装置进行了性能测试，试验数据说明系统工作状态较好，可以满足低压配电网自动化对低压脱扣器的各项要求。

AC system operating voltages from 120 to 600 VAC.

低压交流电系统中从120到600 VAC的电压称为低压。

This series of instruments for low-voltage, medium voltage, high-voltage switchgear and distribution systems, central station monitoring system, generator set systems, building automation systems, energy management system, such as factories, able to measure three-phase three-wire, three-phase four-wire system current, voltage, active power, reactive power, apparent power, active power, reactive power, power factor, frequency, voltage triangular openings, the largest open-shaped voltage power parameters, at the same time with a remote, remote control function.

该系列 仪表适用于低压、中压、高压开关和配电系统、中心电站监测系统、发电机组系统、楼宇自控系统、工厂能量管理系统等，能够测三相三线，三相四线系统的电流、电压、有功功率、无功功率、视在功率、有功电能、无功电能、功率因数、频率、开口三角形电压、最大开口形电压等电力参数，同时带有遥信、遥控功能。

In the whole system, the inner leak system is occurred to the lower pressure bypass system, this will directly cause the high quality reheated steam to reach to condenser, meanwhile increase the heat load of condenser, and the economy benefit of the unit will decreased.

整个系统存在的内漏主要是低压旁路低压旁路的泄漏，直接造成了高品质的再热蒸汽短路到凝汽器，同时增加了凝汽器的热负荷，对机组经济性的影响较大。

The result showed that the strong storm followed by mesoscale squall line was primary cause of strong sandstorm producing, steps and ladders short wave trough of 500 hPa was great criterion triggering system for the mesoscale squall line producing, the essential dynamic condition was provided by distortion field and the mesoscale low pressure of 700 hPa for the strong sandstorm forming and maintaining in mid-west of Hexi Corridor, the deep vertical circulation development condition was basic power that urged squall line to occur and sand dust to curl up, which was provided for the deep convection development by superimposition of lifting movement before ground cold front and ascendant current of secondary circulation in upper air jet entrance region, temperature and the barometric gradient around the cold front was enlarged by enhancement of ground thermal low and temperature diurnalvariation of afternoon, by which essential thermal energy unstable condition was provided for the gale and strong sandstorm eruption, the strong sandstorm appeared in downstream of -200 m^2s^(-2) center of vertical helicity, the vertical helicity had good instruction significance for development of squall line and landing region of sandstorm, the mesoscale squall line occurred in unstable stratification, basic condition of potential energy transforming as kinetic energy was provided by strong unstable stratification for the strong sandstorm forming and developing.

结果表明：中尺度飑线所伴随的强风暴是产生强沙尘暴的主要原因；500 hPa阶梯短波槽是中尺度飑线产生的大尺度触发系统，河西走廊中西部700 hp变形场、中尺度低压为强沙尘暴形成和维持提供了必要的动力条件；地面冷锋前上升运动与高空急流入口区次级环流的上升气流的叠加，为深对流发展提供了深厚的垂直环流发展条件，是促使飑线发生和沙尘卷起的基本动力；地面热低压的加强和午后气温的日变化加大了冷锋前后的温度和气压梯度，为大风、强沙尘暴爆发提供了必要的热力不稳定条件；强沙尘暴出现在垂直螺旋度为－200平方公尺/s^2中心的下游，垂直螺旋度对飑线的发展和沙尘暴的落区具有较好的指示意义；中尺度飑线发生在不稳定层结内，较强的不稳定层结为强沙尘暴形成、发展提供了位能转化为动能的基本条件。

I am sure after a few weeks of adaptation and familiarization I will have no difficulty in functioning on a daily basis in an English speaking society or in participating fully in graduate studies.

在大学的三年的学习生活不仅给予我自身的充实，更重要的是磨练和培养了我较强的自觉能力和严谨，踏实的作风以及不怕困难的精神，对未来充满了信心！

As the first volcanoes erupted, one of the gases that bellowed out was steam.

在第一批火山喷发时，喷出的气体之一就是水蒸汽。