接地电阻值选择多大合适？
How appropriate is the selection of grounding resistance?
接地电阻值选择是设计人员的考虑范围，正常的设计思想是将接地电流限制在某个数值以下即可，比如10KA，20KA等，一般限制在25KA以内，以便于降低断路器的造价以及铜排和电缆的截面积。另外也不能过小，要保证保达到护装置的灵敏性要求。
The selection of grounding resistance value is considered by the designer. The normal design idea is to limit the grounding current to a certain value, such as 10KA, 20KA, etc. and generally to 25KA, so as to reduce the cost of circuit breakers and the cross-section area of copper bars and cables. In addition, it should not be too small to ensure the sensitivity of the protection device.