国内专家提问IEC专家(中文版)
PROBLEMS
IEC 60364 - 4 – 41
GB16895.21
Protective equipotential bonding 保护等电位联结
According to IEC61140 5.2.5 and IEC 60364-4-41 411.1, shall protective equipotential bonding be provided for outdoor TN and TT system with automatic disconnection of supply?
根据IEC61140 （GB/T17045）5.2.5及IEC 60364-4-41 （GB16895.21）411.1，应为带有自动断电保护的户外TN和TT系统，提供保护等电位联结吗？
What kind of earthing systems commonly used for external lightings (including street lighting) in foreign countries?
在国外，外部照明（包括路灯）一般使用哪类接地系统？
The permissible maximum disconnection time5 s or 1 s for circuits defined by IEC 60364-4-41 411.3.2.3and 411.3.2.4, in case of without protective equipotential bonding, can it ensure the protection against electric shock?
IEC 60364-4-41（GB16895.21）411.3.2.3和411.3.2.4规定，允许最大断电时间5 s 或1 s，在没有保护等电位联结的情况下，能确保防电击吗？
Wherever the steel reinforcement of concrete structures to be considered as external conductive parts, shall it be welded or it may be wrapped is allowable for protective equipotential bonding purpose? What about for down conductor of lightning protection system?
将混凝土结构加强钢筋作为外部可导电部分考虑的任何情况下，应将其作为保护等电位联结进行焊接或缠绕吗？防雷系统的引下导体是怎样的？
For building floors without steel reinforcement, shall it to be provided additional protective equipotential bonding? (e.g. mesh)
没有钢筋的建筑楼层，应提供附加保护等电位联结吗？（比如：金属网）
Fault loop impedance Z S 故障回路阻抗Z S
Fault loop impedance Z S of LV system is calculated by fundamental sequence impedance or by zero sequence impedance?
低压系统的故障回路阻抗，是按基本阻抗还是按0区阻抗计算？
TT system
解释：根据IEC 60364-4-41（GB16895.21）411.5.1，由相同的保护电器予以保护所有外露导电部分，应通过保护导体连接至他们的公共接地极。
Clarify: In outdoor or wet locations, R A≤ U L./I D n, conventional touch voltage U L≤ 25 V. 澄清：户内或潮湿场所，R A≤ U L./I D n, 转换为接触电压U L≤ 25 V.
IT system
Explain: Why isolation device shall be provided for neutral conductor of IT system with isolated neutral?
解释：为何中性线隔离的IT系统，仍然要在中性线上安装隔离电器？
What is the typical range of operating value of the insulation resistance for IMD? (several ten kΩor 0.5 MΩ)
绝缘监测电器（IMD）的绝缘电阻的典型动作值范围是多少？（几十kΩ或0.5 MΩ）PELV
Where is PELV system commonly suitable (or not suitable) to be used?
那些场合一般适合（或不适合）使用PELV？
IEC 60364 – 4 – 42
GB16895.2
Protection against thermal effects 热效应保护
Explanation: clause 422.3.9 for protection against fire.
说明：422.3.9 条款是针对防火的规定：
422.3.9 末端回路及用电设备应按以下要求进行绝缘故障保护
a）在TN和TT系统中，应使用额定剩余动作电流IΔN≤300mA的RCD
b）在IT系统中，应提供绝缘监测电器监测整个装置，或在末端回路中使用RCM。做为选择，可使用a）中规定的额定剩余动作电流的RCD，在发生二次故障时予以断电保护。
Introduction on protection against fire risk that normally for public and office buildings and dwellings (including selection of cable types) in foreign countries.
在防范火灾风险方面，请介绍一下国外对于公共建筑、办公建筑、住宅（包括线缆类型的选择）的一般情况。
IEC 60364 - 4 – 43
GB16895.5
Overload protection 过载保护
Explain the factor 1.45 of formula I2≤ 1.45I Z, (regarding the tolerant of the characteristic curves, cyclic load or inrush current etc.)
解释公式I2≤ 1.45I Z,中的系数1.45，（依据特性曲线的公差容限？周期性负荷？浪涌电流？等等）
IEC 60364 - 4 – 44
GB/T16895.16
Earthing resistance R E 接地电阻R E
1 HV neutral solid earthing and low resistance earthing
1 高压中性点可靠接地与低阻接地
- R E ≤2000 V/I E instead of R E ≤1200 V/I E (derived from IEC 60364-4-44:2007 Table 44.A1 and Table 44.A2);
- R E ≤2000 V/I E代替R E ≤1200 V/I E（摘自IEC 60364-4-44:2007表44.A1及表
44.A2）
Note: The GB code considers the earth fault current of≥110 kV system can be ≥25 kA, in order to avoid R E too low, as well as the difficulties for separating the HV and LV earthing within the substation, in this case R E is allowed to be ≤ 5000 V/I E. (with provision of certain equipotential bonding and screening)
注：GB考虑≥110 kV系统的接地故障电流可能≥25 kA，为避免R E过低，以及考虑到在变电站分隔高压与低压接地系统的困难，在这种情况下，接地电阻允许≤5000 V/I E.。（带有某种等电位联结和屏蔽措施）
Comment: As a result, the power frequency stress voltage U1 or U2 exceed the limit values defined by GB 16895.11(idt. IEC 60364-4-442:1993) and GB 61935.1(idt. IEC60664-1), the LV equipment may be damaged under earth fault situation.
注释：其结果，源自U1或U2的电压，超过了GB 16895.11(idt. IEC 60364-4-442:1993) and GB 61935.1(idt. IEC60664-1)定义的限值，低压设备可能在接地故障时损坏。
What are the experiences and solutions concerning this problem in foreign countries? 国外在此问题上有何经验与解决方案？
- The earthing of TN system is only allowed to be connected to the HV system R E .
- TN系统的接地只允许连接至高压系统的R E
Comment: As a result, the implementation of TT and IT system are excluded, as well as the HV and LV earthing of TN system is not permitted to be separated.
注释：其结果，TT和IT系统被排除在外，而且TN系统的高压与低压接地系统不允许被分隔
2 HV neutral isolated or with resonance low or high resistance earthing
2 高压中性点隔离或合理低阻或高阻接地
- For power station and substation: R E ≤120 V/I E instead of R E ≤250 V/I E ..
- For power grid supplying LV consumer: R E ≤ 50 V/I E .
- 发电厂与变电站：R E ≤120 V/I E代替R E ≤250 V/I E …
- 为低压用户供电的电网：R E ≤ 50 V/I E
Comment: Not necessary to reduce the value of R E under perfect protective equipotential bonding. 注释：在有可靠保护等电位联结的情况下不必降低R E值
Some people consider that fault voltage U f and fault duration t may not be limited according to IEC 60364-4-44 Figure44.A2 in case of under perfect protective equipotential bonding.
有些人认为，根据IEC 60364-4-44 （GB/T16895.16）图44.A2，在有可靠保护等电位联结的情况下，可不限制故障电压U f与故障持续时间t。
Multiple source system 多电源系统
IEC 60364-4-44 clause 444.4.6 requires multiple sources with N conductor single point eartting. Conform that figure44.R7B can be used either for parallel or non parallel in normal operation (The figure not mentions the relevant switches on the interconnection line conductors and PEN conductor).
IEC 60364-4-44 （GB/T16895.16）444.4.6要求带N导体的多电源系统单点接地。符合图44.R7B，在正常运行时既可用于并联也可用于非并联。（图中未提及在线导体及PEN导体上各连接处的相关开关情况。）
.
In China, a lot of PEN conductor of multiple source systems wherever up to now are still implemented more than one point earthing (see figure below), however some of them no EMI were occurred that has been told. May be due to using TN-C system is actually suitable for those locations (see figure below: N is parallel with PE) without EMC problem or even no risk of fire and explosion.
在中国，很多多电源系统的PEN导体，到目前为止，无论何种场合，仍然执行多点接地（如下图），尽管被告知这样会导致电磁干扰，但其中一些并未发生过电磁干扰（EMI）。
也许由于使用TN-C系统(见下图：N线与PE线并联)，实际上是适合那些不存在电磁兼容(EMC)或没有火灾及爆炸风险场合的。
Clarify that the main bus bar is TN-S system, then the out going feeders from the bus bar shall not be TN-C system (see figure44.R7B Note b), otherwise in this case the PEN bus bar will be multiple point earthing.
请澄清：母排是TN-S系统，而后从母排引出的馈线不应是TN-C系统（见图44.R7B 注b），否则在这种情况下，PEN排将形成多点接地。
Wherever the sources are located in power grid (belongs to Power Company), the connection diagram as follow usually shall be used.
在电网（属于供电局）供电的任何场合，通常应采用以下连接图示。
Protective earthing and functional earthing 保护接地与功能接地
444.5.1所有保护和功能接地导体宜连接至单一总接地端子。
542.1.1 对于保护和功能接地的设置，可共同地或是分开地使用。
Clarify the above different expression in case of what conditions the functional earthing and the protective earhting shall be neither connected or separated, and what is the value of earthing resistance shall be selected？
请澄清：以上不同表示在何种情况下，功能接地与保护接地应连接在一起或分开设置？还有，接地电阻值应为几何？
Note: In China, when the above two kind of earthing is connected to gether, the earthing resistance usually shall be selected not more than 1Ω.
注：在中国，当上述两种接地被连接在一起时，接地电阻通常要求不大于1Ω
IEC 60364 - 5 – 54
GB 16895.3
Corrosion problems of earth electrodes 接地极腐蚀问题
According to IEC 60364-5-54 543.2.2, because of the steel reinforcement of the building floors, columns and beams etc. subject to mechanical stress in normal service, so that are not permitted to be used for PE and protective bonding conductors?
根据IEC 60364-5-54（GB 16895.3）543.2.2，因为建筑物地板、柱子和梁等的钢筋受其正常功能的机械强度制约，是不允许用于PE或保护联结导体的吗？
Explain:
说明：
C.4 对于混凝土包裹之外的其他需被接地的（电气）装置，其功能接地极可能出现的腐蚀问题
包裹在混凝土之内的普通钢导体，其电化学电势与在土壤中的铜导体相同。因而，有电化学腐蚀的危险。
Is it no corrosion problems where the stainless steel electrodes embedded in soil connected with concrete foundation steel reinforcement?
在土壤中与混凝土基础钢筋连接在一起的不锈钢接地极，没有腐蚀问题吗？
IEC 60364 - 5 – 53
GB16895.4
RCD
Introduce any typical cases regarding the high risk of break of neutral conductors mentioned by 64/1665/CDV 531.2.3.2.
请根据64/1665/CDV 531.2.3.2.对中性线导体断裂高风险的修订，介绍典型案例。
In case of provided equipotential bonding but usually lack of maintenance by BA4 (BA5) personnel, are there any risks that RCDs use in dwellings that may not ensure the safety protection against break of neutral conductors (including poor connection)? 在已提供保护等电位联结但缺少BA4（受过培训的人）(BA5)（专业技术人员）人员维护的情况下，在没有中性线断裂（包括连接不良）保护的住宅中使用的RCD，有风险吗？
The supply voltage of RCDs are selected provided protection not less than 50 V (GB standard), is it superfluous for ensuring the safety protection?
用于提供保护的RCD供电电压规定为不小于50 V (GB 规定)，对于确保安全保护是多余的吗？
IEC 60364 - 5 – 56
Safety service 安全供电
Briefly introduce the definition of electric supply system for safety services (emergency electric supply) and standby electric supply system.
请简单介绍用于安全供电（应急电源）及后备电源系统的定义
Note: In China, some safety services supply system, normally shall be decided by the scale of the premises (e.g.emergency power supply only shall be provided for≥50 m high buildings or
hospital with≥ 500 patient beds, etc. ).
注：在中国，一些安全供电电源系统，通常以规模为前提（例如：应急电源仅提供给≥ 50 m的高层建筑或≥ 500 个床位的医院）。
Introductions focus on:
560.5.3 Prefer to use IT system.
560.5.4Failure in control and bus system of normal installation shall not affect the safety services.
560.6.7 The condition for safety source which in addition may be used for other than safety services.
560.6.5 The condition of public network independent feeders to be used for safety services.
560.6.9 Special requirements for two supply sources operate in parallel.
560.8.1 Wiring systems
请着重以下条款进行介绍：
560.5.3 IT系统的优越性
560.5.4 正常装置的控制与总线系统故障不应影响安全供电
560.6.7 另外可用于非安全供电的安全电源的条件
560.6.5 用于安全供电的公共电网独立馈电的条件
560.6.9 双电源并联运行的特殊要求
560.8.1 布线系统
Introduce the typical single line diagram for safety services supply system (Including the implementation of PC, CB and CC type of automatic transfer switches) for example.
请以示意图方式，举例介绍安全供电系统（包括PC、CB及CC型自动转换开关的实施）。