The safe grounding of generator set is a necessary prerequisite to ensure the personal safety of operators and the reliable operation of equipment, and the equipment management personnel must ensure the safe grounding of generator set. The measures to ensure the safe grounding of generator set are mainly divided into three categories: working grounding, protective grounding and protective zero grounding. Jichaihuan can explain the specific contents below:

一、工作接地

1、 Working grounding

（1）降低触电电压。对于中性点不接地的系统，当一相接地而人体触及另外两相之一时，触电电压为相电压的1.7倍以上；而对于中性点接地系统，触电电压就降到接近或等于相电压。

(1) Reduce the electric shock voltage. For the system with ungrounded neutral point, when one phase is grounded and the human body touches one of the other two phases, the electric shock voltage is more than 1.7 times of the phase voltage; For the neutral grounding system, the electric shock voltage drops to close to or equal to the phase voltage.

（2）迅速切断故障设备。对于中性点不接地的系统，当一相接地时，由于导线和地面存在电容和绝缘电阻，可以构成电流通路，接地电流很小，不足以使保护装置动作而切断电源，不能确保人身安 全。而对于中性点接地的系统，当一相接地后接地电流较大，保护装置会迅速动作，断开故障点。

(2) Quickly cut off the faulty equipment. For the system with ungrounded neutral point, when one phase is grounded, due to the capacitance and insulation resistance between the conductor and the ground, it can form a current path. The grounding current is very small, which is not enough to make the protective device act and cut off the power supply, and can not ensure personal safety. For the neutral grounded system, when one phase is grounded, the grounding current is large, and the protection device will act quickly to disconnect the fault point.

（3）降低电气设备对地的绝缘水平。在中性点不接地的系统中，当一相接地时，将会使另两相得对地电压升高到线电压。而对于中性点接地的系统，当一相接地时，另两相的对地电压只接近于相电压，故可降低电气设备和输电线路的绝缘水平。

(3) Reduce the insulation level of electrical equipment to ground. In a neutral ungrounded system, when one phase is grounded, the ground voltage of the other two phases will rise to the line voltage. For the neutral grounded system, when one phase is grounded, the ground voltage of the other two phases is only close to the phase voltage, so the insulation level of electrical equipment and transmission line can be reduced.

二、保护接地保护接地常用于中性点不接地的低压系统中，它的作用是：当电动机某一绕组的绝缘结构已破坏使外壳带电时，如果未接地，人体触及外壳，相当于单相触电，就可能发生触电的危险。而如果采用了保护接地，人体触及外壳时，由于人体的电阻与接地电阻并联，由于人体电阻；远大于接地电阻，通过人体的电流就很小，就不会发生触电的危险。

2、 Protective grounding protective grounding is commonly used in the low-voltage system with ungrounded neutral point. Its function is: when the insulation structure of a winding of the motor has been damaged and the shell is charged, if it is not grounded, the human body touches the shell, which is equivalent to single-phase electric shock, there may be the risk of electric shock. If protective grounding is adopted, when the human body touches the shell, due to the resistance of the human body in parallel with the grounding resistance, due to the resistance of the human body; Far greater than the grounding resistance, the current passing through the human body is very small, and there will be no danger of electric shock.

三、保护接零保护接零常用于中性点接地的低压系统中，它的作用是：当电动机某一绕组的绝缘结构已破坏而与外壳相接时，由于采用保护接零，就形成单相短路，迅速将这一相中的熔丝熔断，外壳便不再带电。即使在熔丝熔断前人体触及外壳时，也由于人体电阻远大于线路电阻，通过人体的电流也很微小，不会发生触电危险。

3、 Protective neutral connection protective neutral connection is often used in low-voltage systems with neutral grounding. Its function is: when the insulation structure of a winding of the motor has been damaged and connected with the shell, due to the use of protective neutral connection, a single-phase short circuit will be formed. Quickly fuse the fuse in this phase, and the shell will no longer be charged. Even when the human body touches the shell before the fuse is blown, the current passing through the human body is very small because the human body resistance is much greater than the line resistance, so there will be no danger of electric shock.

另外还需注意，发电机零线接地要考虑具体的情况，首先要确认变压器是否有漏电保护，一般进口发电机组是零地合一的，用的时候要拆掉，否则变压器有漏电保护的情况下很可能会跳。而国产发电机组的地线通常在地盘上，单独接地，零线和市电的零线接在一起。相线（三相线）要用专用开关把市电和发电做互锁控制，以免市电加在发电机组上。

In addition, it should be noted that the specific situation should be considered for the zero line grounding of the generator. First, it is necessary to confirm whether the transformer has leakage protection. Generally, the imported generator set is zero ground in one, and it should be removed when it is used, otherwise the transformer may jump under the condition of leakage protection. The ground wire of domestic generator sets is usually grounded separately on the site, and the zero wire is connected with the zero wire of municipal power supply. The phase line (three-phase line) shall use a special switch to interlock the mains power and power generation, so as to prevent the mains power from being added to the generator set.