wpcily 发表于 2010-6-11 12:46

参考标准EN60950, Clause 5.1.1
However, if it is clear from a study of the circuit diagrams of either STATIONARY PERMANENTLY
CONNECTED EQUIPMENT or STATIONARY PLUGGABLE EQUIPMENT TYPE B, that has a PROTECTIVE
EARTHING CONDUCTOR, that the TOUCH CURRENT will exceed 3,5 mA r.m.s., but that the
PROTECTIVE CONDUCTOR CURRENT will not exceed 5 % of input current, the tests of 5.1.5, 5.1.6
and 5.1.7.1 a) are not made.
NOTE In the above case, the requirement of 5.1.7.1 b) continues to apply.

superleaf 发表于 2010-6-11 17:49

接触电流一般是不能超过3.5mA的，除了一些特别的设备～～～

superleaf 发表于 2010-6-11 17:56

5.1.7 Equipment with touch current exceeding 3.5mA有提到这个问题，可以看下～～

wpcily 发表于 2010-6-12 08:57

If the result of the TOUCH CURRENT measurement on any of the above equipments exceeds
3,5 mA r.m.s., the following requirements a) and b) apply, and also, if relevant, those in
5.1.7.2.
a) The r.m.s. PROTECTIVE CONDUCTOR CURRENT shall not exceed 5 % of the input current per
line under normal operating conditions. If the load is unbalanced, the largest of the three
line currents shall be used for this calculation.To measure the PROTECTIVE CONDUCTOR CURRENT, the procedure for measuring TOUCH CURRENT is used but the measuring instrument is replaced by an ammeter of negligible
impedance; and
b) one of the following labels, or a label with similar wording, shall be affixed adjacent to the
equipment AC MAINS SUPPLY connection:
WARNING HIGH LEAKAGE CURRENT EARTH CONNECTION ESSENTIAL BEFORE CONNECTING SUPPLY WARNING
HIGH TOUCH CURRENT EARTH CONNECTION ESSENTIAL BEFORE CONNECTING SUPPLY
Compliance is checked by inspection and measurement.

wpcily 发表于 2010-6-12 08:59

各位貌似误解意思了，我不是关心能不能超过3.5mA的问题，而是如何测量保护导体电流的问题？不然如何判定超过3.5mA的设备有没有超过输入电流的5%？

wpcily 发表于 2010-6-12 09:04

“To measure the PROTECTIVE CONDUCTOR CURRENT, the procedure for measuring TOUCH CURRENT is used but the measuring instrument is replaced by an ammeter of negligible impedance”,标准的解释是按测试接触电流的方法（只是将测量仪器换成没有阻抗影响的电流表），但是UL则要求测试正常工作是保护接地导体到大地的实际电流值，所以困惑，且实际两种方法测试都没出结果，所以更纳闷，是否有其他特别测试条件或要求？

superleaf 发表于 2010-6-12 10:51

UL和EN的标准关于漏电流超3.5mA的测试方法都是一样的吧，我看标准写的都是一样的，我估计用“没有阻抗影响的电流表”测不出结果，可能是因为电流表不是毫安级别的，如果是毫安级别的话应该测得出来。

wpcily 发表于 2010-6-12 10:53

恩，标准写的一样，但是UL机构的人要求按保护接地导体到大地的电流测试值；电流表没有问题，可以测试mA的，采用的是Fluke万用表测试的。

superleaf 发表于 2010-6-12 12:39

在小于3.5mA的情况下，我们用228表或U1U2表来测漏电流是为了模拟人体网络，我觉得电流大于3.5mA应该属于一个对人体构成反应的电流了，当大于3.5mA的时候，就不能用来模拟人体网络了，所以用电流表来测量。用电流表来测量纯粹是为了测量“保护接地导体到大地的电流值”，所以UL机构的人要求按保护接地导体到大地的电流测试值，是有它的道理的。

wolfxu 发表于 2010-7-27 13:48

这个测试直接将地线剪开串入电流表量测就Ok啊，得出的结果小于rating INPUT 5%，就好
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