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微之欢颜 发表于 2010-4-6 21:17

爬电距离小于电气间隙的实例有吗

]一般情况下，测量电气间隙和爬电距离时，爬电大于电气；
标准上有说爬电距离小于电气间隙的时候，默认等于电气间隙值。
请问是否有爬电距离小于电气间隙的实例呢？否则何来此说法？期待大家指教哦

Andy.Yang 发表于 2010-4-6 21:30

In reality, the creepage distance can not be lower than clearance distance. Only in one case, you can find the clearance distance is bigger than creepage distance. for example, you know the working voltage of two opposite polarities, and check the related standards and find the creepage distance is 8mm, but check the clearance requirement, you can find the distance is 10mm, at this time , you must take creepage also 10mm. This sole case only occurs when you check the standards requirements, in reality, you can not find the case that the creepage distance is lower than clearance distance...

微之欢颜 发表于 2010-4-6 21:44

楼上的意思是指：
依据标准，爬电的要求值 小于 电气的要求值 的时候，自动默认把 爬电要求值改为电气要求值；
而不是指具体测得值；
那么就是说 实际情况 任何条件下 测得的爬电不可能小于电气是吗？
谢谢ANDY~~~

Andy.Yang 发表于 2010-4-7 08:51

Yes, you are right. In reality, you can not find the creepage is lower than the clearance...
By the way, if you wanna know more information about the safety distance, you can read UL840..

Alexsong 发表于 2010-4-7 12:08

引用第2楼微之欢颜于2010-04-06 21:44发表的:
楼上的意思是指：
依据标准，爬电的要求值 小于 电气的要求值 的时候，自动默认把 爬电要求值改为电气要求值；
而不是指具体测得值；
那么就是说 实际情况 任何条件下 测得的爬电不可能小于电气是吗？
谢谢ANDY~~~

1. 当通过工作电压计算出的爬电距离要求值小于电气间隙要求值时, 则爬电距离的要求值和电气间隙的要求值相同, 例如计算出的Cl为4.4, Cr为4.0, 则应将Cr修正到4.4.
2. 实际情况中测得的爬电距离不是不可能小于电气间隙, 而是这种情况非常非常少.

guanito 发表于 2010-4-7 12:11

我很想看一下爬电距离小于电气间隙实例，谁有这方面资料，请放上来共享一下

微之欢颜 发表于 2010-4-7 17:17

非常感谢3楼、4楼的意见！明白了！谢谢！UL840没看过，呵呵

浪子边城 发表于 2010-4-7 18:11

引用第5楼guanito于2010-04-07 12:11发表的:
我很想看一下爬电距离小于电气间隙实例，谁有这方面资料，请放上来共享一下
根据标准要求，只有可能计算得到爬电距离小于空间距离，但由于此时需要用空间距离来评估，所以，不会有爬电距离小于空间距离的实例

Andy.Yang 发表于 2010-4-7 18:14

If you can know how to measure the clearance and creepage, then you'll know that's impossible...

猛龙不过江 发表于 2010-4-7 18:15

引用第1楼Andy.Yang于2010-04-06 21:30发表的:
In reality, the creepage distance can not be lower than clearance distance. Only in one case, you can find the clearance distance is bigger than creepage distance. for example, you know the working voltage of two opposite polarities, and check the related standards and find the creepage distance is 8mm, but check the clearance requirement, you can find the distance is 10mm, at this time , you must take creepage also 10mm. This sole case only occurs when you check the standards requirements, in reality, you can not find the case that the creepage distance is lower than clearance distance...
   2L,很牛

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