Class 2+ 功能接地讨论
请问论坛里面有没有对Class 2+ 功能接地结构比较熟悉的，讨论一下像这种2类设备带功能接地的，一般认证机构划分到Class I 还是Class II呢？
是依据什么？
如果划分到Class 2， 是不是需要标“回”符号呢？
UL 60950 2.6.2 有对这个功能接地详细描述：
2.6.2 Functional earthing
If FUNCTIONAL EARTHING of accessible or inaccessible conductive parts is necessary, all of the
following apply to the FUNCTIONAL EARTHING circuit:
– the FUNCTIONAL EARTHING circuit shall be separated from parts at HAZARDOUS VOLTAGES in
the equipment by either:
• DOUBLE INSULATION or REINFORCED INSULATION; or
• a protectively earthed screen or another protectively earthed conductive
part, separated from parts at HAZARDOUS VOLTAGES by at least BASIC INSULATION;
and
– it is permitted to connect the FUNCTIONAL EARTHING circuit to a protective earth terminal
or to a PROTECTIVE BONDING CONDUCTOR; and
– wiring terminals to be used only for FUNCTIONAL EARTHING shall not be marked by the
symbol (60417-IEC-5017) or by the symbol (60417-IEC-5019), except that,
where a wiring terminal is provided on a component (for example, a terminal block) or
subassembly, the symbol is permitted; and
NOTE Other markings such as one of the symbols, (IEC 60417-5018 (DB:2002-10)) or (IEC 60417-5020
(DB:2002-10)), if appropriate, are permitted.
– for internal FUNCTIONAL EARTHING conductors, the colour combination green-and-yellow
shall not be used except in multipurpose preassembled components (for example,
multi-conductor cables or EMC filters); and
– in a power supply cord where a conductor having green-and-yellow insulation is
used only to provide a FUNCTIONAL EARTHING connection:
• the equipment shall not be marked with the symbol (IEC 60417-5172
(DB:2003-02)); and
• there are no requirements other than those in 3.1.9 regarding the
termination of this conductor at the equipment end.
MARCH 27, 2007 CAN/CSA-C22.2 NO. 60950-1-07 ♦ UL 60950-1 89 这个插座就是CLASS 2+function eathing 使用的，中间那个pin 是不接一次侧的地，
而是用一根黄滚绿地线接到输出端。
我不是很清楚功能接地的作用到底是什么，我有请教我们的研发工程师，好像也不是很清楚这个。 应该是Class II,一般情况下，它不是起保护接地作用。 回字符号还是要的！
但是这段标准中有这样一句话， 如果电源线中某一导体为黄绿双色且仅作为功能绝缘连接， 则回字符合不可用！ 算ClassI类设备
单要满足CLASS II类设备的绝缘要求 我们以前有一个产品也是这样的， 是算做Class II类的.
因为class I =需要基本绝缘+保护地,而功能地不能代表一种防电击的能力. 我也认为算II类器具, 这种产品我也见过，一般医疗电源有这种设计，3PIN的插座，中间的功能性PE pin直接连接到PCB输出端口（－）上，不能定于成classI，liao_yl 说得对“因为class I =需要基本绝缘+保护地,而功能地不能代表一种防电击的能力.”所以只能定义成class II类，但是可以不用加“回”符号。
