Mike Krzyzewski is really a famous coach of Dream Team. She has coached north america men's basketball team for some time, that's clinched numerous medals for his country. Following Londonfl jerseys supplyn Olympic was over, Krzyzewski told The Associated Press that this game will be his final one as national coach, a job he's held for seven years. He had left open the possibility of swomen nfl jerseystaying with the team beyond the London Games, when practice on Saturday said these will be his last Olympics.When asked if he was sure, Krzyzewski didn't hesitate before again saying, "yecheap nfl jerseys wholesales," this will be his last game "If we could win it, then it might be three major championships in a row, i always do not know when that has been done because we haven't usually won http://govoriotkrito.bg/libs/nflcn08.htmthe globe championships," Krzyzewski said. "It becomes an enormous thing for the program." Whatever, he's an awesome coach. His achievement are going to be remembered by the country.cheap nfl jerseys
技术支持 Support
搜索 Search
你的位置:首页 > 技术支持

高压断路器基本知识

2014-8-8 11:01:04点击:

高压断路器(或称高压开关)它不仅可以切断或闭合高压电路中的空载电流和负荷电流,而且当系统发生故障时通过继电器保护装置的作用,切断过负荷电流和短路电流,它具有相当完善的灭弧结构和足够的断流能力,可分为:油断路器(多油断路器、少油断路器)、六氟化硫断路器(SF6断路器)、真空断路器、压缩空气断路器等。

选用指南

一般原则

为保证高压电器在正常运行、检修、短路和过电压情况下的安全,高压电器应按下列条件选择:
① 按正常工作条件包括电压、电流、频率、机械荷载等选择;
② 按短路条件包括短时耐受电流、峰值耐受电流、关合和开断电流等选择;
③ 按环境条件包括温度、湿度、海拔、地震等选择;
④ 按承受过电压能力包括绝缘水平等选择;
⑤ 按各类高压电器的不同特点包括开关的操作性能、熔断器的保护特性配合、互感器的负荷及准确等级等选择。
正常工作
①按工作电压选择选用的高压电器,其额定电压应符合所在回路的系统标称电压,其允许最高工作电压Umax不应小于所在回路的最高运行电压Uy,即Umax ≥ Uy。
② 按工作电流选择高压电器的额定电流In不应小于该回路在各种可能运行方式下的持续工作电流Ig,即In ≥ Ig。
短路稳定
① 短路稳定性校验的一般要求
② 短路电流的热效应
③ 短路稳定性校验
2环境条件
① 选择电器的环境温度
② 选择电器的环境湿度
③ 高海拔对高压电器的影响
④ 地震对高压电器的影响 ① 额定短路开断电流的选择
② 额定短路关合电流的选择
③ 额定操作顺序的选择
④ 额定失步开断电流的选择
⑤ 额定异相接地故障电流、发展性故障电流及关于开断电流的选择
⑥ 额定近区故障开断电流的选择
⑦ 额定线路充电开断电流、额定电缆充电开断电流、额定电
容器组开断电流、额定电容器组关合涌流、额定感应电动
机开断电流、额定空载变压器开断电流、额定电抗器开断
电流等的选择。标准中对上述各项开断电流和关合电流未
作规定,但使用中应按制造厂给出的试验数据选用。