隔离变压器供电的设备外壳，如果通过接地极接大地了，是否有安全风险？

Tricity

413.3.6 The exposed-conductive-parts of the separated circuit shall not be connected either
to the protective conductor or exposed-conductive-parts of other circuits, or to earth.

6.5 Protection by electrical separation
Electrical separation is achieved where the following conditions are met:
– basic protection is provided by basic insulation between hazardous-live-parts and exposed-conductive-parts of the separated circuit; and
– fault protection is provided
• by simple separation of the separated circuit from other circuits and earth, and
• by a protective-equipotential-bonding interconnecting exposed-conductive-parts of the separated circuit where more than one item of equipment is connected to the separated circuit. This protective-equipotential-bonding system shall not be earthed.
Intentional connection of exposed-conductive-parts to a protective earthing conductor or to an earthing conductor is not permitted.

Tricity

治学以诚 发表于 2016-6-22 12:28
因为  RA＝1000欧。也比C2小无限多，C2通常是兆欧起跳。
RA与C2分C1上的电压，RA分压显然近于0。

您确定您正确理解了IEC那段话的意思么？

王老的书我虽然看得很少，就看过的而言，多数内容并非是出自他个人的意见，有些其实原本就是IEC的规定，他无非是通过一些例子解释为什么IEC这么规定。

外壳不允许人为接地的原因，我个人认为还是担心有可能引入通过PE导体传递的外部故障电压。