In order to ensure the safety of human body and power system operation, the diesel generator set is usually required to take grounding measures. According to different grounding purposes, it can be divided into working grounding, protective grounding and protective zero connection. The first way: working grounding. Due to the need of operation and safety of power system, the neutral point is often grounded, which is called working grounding. Working grounding has the following purposes: Reduce electric shock voltage. In systems with ungrounded neutral point, when one phase is grounded, and other two phases touch the human body, electric shock voltage is 1.732 times of phase voltage. While in systems with grounded neutral point, electric shock voltage is reduced to equal or close to the phase voltage. Cut off faulty equipment quickly. In systems with ungrounded neutral point, when one phase is grounded, the grounding current is very small( because there is el...