电气工程与自动化专业英语（第3版）课件：高电压绝缘.pptx

高电压绝缘;高电压绝缘;高电压绝缘;高电压绝缘;高电压绝缘;4.难句翻译

[1].Transientovervoltagescausedbylightningstrikestotransmissionlinesandbyswitchingoperationsareoffundamentalimportanceinselectingequipmentinsulationlevelsandsurge-protectiondevices.

由雷击输电线和开关操作造成的暂态过电压,对于选择设备的绝缘水平和过电压保护装置非常重要。

[2].Whenalinewithdistributedconstantsissubjectedtoadisturbancesuchasalightningstrikeoraswitchingoperation,voltageandcurrentwavesariseandtravelalongthelineatavelocitynearthespeedoflight.

当一条具有分布常数的导线受到雷击或开关操作等干扰时，沿线产生和传播的电压和电流波的速度接近光速。;[3].However,duetothereinforcingactionofseveralreflectedwaves,itispossibleforvoltagetobuilduptoalevelthatcouldcausetransformerinsulationorlineinsulationtoarcoverandsufferdamage.

但是,由于数次反射波的加强,有可能使电压增加到一定水平,从而导致变压器绝缘或线路绝缘产生电弧击穿,进而遭受损坏。

[4].Whenvoltagegradientsreachthebreakdownstrengthofthehumidairwithinthecloud,typically5to15kV/cm,anionizedpathordownwardleadermovesfromthecloudtowardtheearth.Theleaderprogressessomewhatrandomlyalonganirregularpath,insteps.

当云层的电压梯度达到潮湿空气的击穿场强(5~15kV/cm)时,形成从雷云到地面的电离路径或先导放电。先导只是无规则地向下逐步推进。;[5].Theseleadersteps,about50mlong,moveatavelcityofabout105m/s.

每级长度约50m,伸展速度约105m/s。

[6].Atypicaltransmission-linedesigngoalistohaveanaverageoflessthan0.50lightningoutagesperyearper100milesoftransmission.

每年每100英里输电线路的雷击停电次数平均不超过0.5次是一个典型传输线的设计目标。

[7].Experiencehasshownthatthechanceofadirecthittophaseconductorslocatedwithin±30°arcsbeneaththeshieldwiresisreduced.

经验表明,直接击中避雷线下方30°内的相导线的机率会减少。;[8].Sincetheshieldwireiselectricallyconnectedtothetower,theotherrefractedwavemovesdownthetower,itsenergybeingharmlesslydivertedtoground.

由于避雷线与铁塔相连，其他反射波的能量沿着塔被安全转移到地???。

[9].Inordertoreduceovervoltagesduetolineenergizingorreclosing,resistorsarealmostalwayspreinsertedincircuitbreakersat345kVanda