通过过电流保护装置进行保护
相间接地保护自动装置的选择
故障和间接接触应通过适当协调
故障回路阻抗的断开时间。
因此，有必要满足以下条件：
Zs公司
·Ia公司≤ U0
哪里：
ZS是故障回路的阻抗（单位：欧姆），包括
-来源；
-线路导体至故障点；
-外露导电部分的保护导体；
-接地导体；
-装置的接地电极；
-电源的接地电极；
我
a是终电路的断开电流，时间如表1所示
配电电路电流不超过32A或1秒以内
对于电流超过32A的终电路；
U0是标称交流均方根对地电压（V）。
自动装置的选择应通过适当协调
故障回路阻抗的断开时间。
关系Zs
·Ia公司≤ U0
可以表示为：
我
一≤ U0=IkL对地Zs
其中，IkL对地是相对地故障电流。因此，可以声明
当跳闸电流Ia时，验证间接接触保护
保护装置的电压（在表1所示的时间内或1s内）较低
比ea的相位

Protection by means of overcurrent protective devices The choice of the automatic device for the protection against phase-to-earth faults and indirect contact shall be carried out by coordinating properly the disconnection times with the impedance of the fault loop. As a consequence, it is necessary to fulfill the following condition: Zs · Ia ≤ U0 where: ZS is the impedance (in ohms) of the fault loop comprising - the source; - the line conductor up to the point of the fault; - the protective conductor of the exposed-conductive-parts; - the earthing conductor; - the earth electrode of the installation; - the earth electrode of the source; I a is the disconnection current in the times shown in Table 1 for final circuits with currents not exceeding 32A or within 1 second for distribution circuits and for final circuits with currents exceeding 32A; U0 is the nominal a.c. r.m.s. voltage to earth (V). The choice of the automatic device shall be made by coordinating properly the disconnection times with the impedance of the fault loop. The relationship Zs · Ia ≤ U0 may be expressed as : I a ≤ U0 = IkL-to earth Zs where IkL-to earth is the phase-to-earth fault current. Therefore, it is possible to state that the protection against indirect contact is verified when the tripping current Ia of the protective device (within the times shown in Table 1 or within 1s) is lower than the phase-to-ea