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发表于 2024-1-18 10:09:03
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刚刚看到，感谢，我再算下。
另外，十根引下线，我写信给iec的编委了，回复说，这是MT21会议讨论的结果，同时也承认，不是所有国家都认为这样够安全比如德国。
you refer to clause 8.1 and 8.2 of IEC 62305-3. The “protection measure” you mentioned is a compromise which the responsible MT21 (former MT8) has found for this problem. The idea is, that with at least 10 down-conductors (d.-c.) the current sharing is so good, that only a small amount of current flows over the d.-c. under consideration. And with that the potential difference on the ground (responsible for the step voltage) and the potential difference along the d.-c. itself (mainly responsible for the touch voltage) is so low, that it can be accepted.
However, in the meantime the discussion in the MT21 went on. And therefore, in the next edition (Ed.3) of IEC 62305-3, to be published hopefully in 2024, the 10 d.-c. will be modified to 10 natural d.-c. (steel columns or steel reinforced concrete columns).
And, to be frank, some NC (e.g. Germany) still give a warning notice, that this “protection measure” does not seem enough for them to be acceptable. |
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