在D级、C级SPD保护产品中，最大持续工作交流电压（Uc）的选择有什么要求？
<p>新手求教。</p> <p>新手求教。</p><p> </p><p> </p><p>在GB50057-94（2000版）规定了在不同接地系统的Uc值，生产厂家一般能提供不同级别的几种Uc值供选择，对于220V/380V的电源系统，考虑到电源的波动性，D级通常选择Uc=275V，它的限制电压Up≤1200V，在C级通常选择Uc=385V或420V，它的限制电压Up≤1800V或1900V，在B级通常选择Uc=550V或510V，它的限制电压Up≤2500V。有的用户提出在D级应该选择Uc=385V，理由是当发生电源接地故障引起电压升高时，不至于损坏SPD，殊不知它的限制电压超出了1500V（Up≤1800V），设备将得不到很好的保护。接地故障引起的电源电压升高毕竟是极少出现的故障，所引起的设备损坏不属于SPD保护的范畴。 </p> 学习了，谢楼上主详细讲解。 Defeat the Raven God<br />Now it is time for you to wow power leveling kill the boss
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<br />that can be summoned from the room that is right
<br />before the blast wow power leveling boss.
<br />There are a lot of steps required to get Druid Epic Flight Form, but once you have it you will be
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<br />glad that you do. Be sure to do everything in order so that you can be certain that you haven’t
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<br />skipped any wow power leveling steps
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<br />and that you are prepared for the next challenge.
<br />Be sure to bookmark this page and check out the other WoW Druid guides we have available.
<br />This is yet another wow gold guide that I have
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<br />found online and it has a great foundation for powerleveling effectively, so I decided to add it
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<br />here for your enjoyment! Why add another powerleveling basics
<br />guide? Great aion gold question, I added it here
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<br />because I feel that if you don't have the powerleveling
<br />basics cheap wow power leveling down you will
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<br />fundamentals to really become a master. Just think of this as a
<br />beginning mastery buy wow power leveling course
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<br />for World of Warcraft powerleveling!
<br />1) Take as many warcraft gold quests as possible and
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<br />at the same time, try not to do quests one at a time. When
<br />entering aion powerleveling a new
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<br />area, find all the quests from NPC's first, before you start killing things.
<br />2) A complementary group of 2 or 3 (such as tank + healer) is sometimes far better than solo'ing.
<br />
<br />Especially cheap aion power leveling when a
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<br />quest calls for "kill X amount of something". Use groups when they suit you. :(
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