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）降低觸電電壓。對于中性點不接地的系統(tǒng)，當一相接地而人體觸及另外兩相之一時，觸電電壓為相電壓的1.7倍以上；而對于中性點接地系統(tǒng)，觸電電壓就降到接近或等于相電壓。

(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）迅速切斷故障設備。對于中性點不接地的系統(tǒng)，當一相接地時，由于導線和地面存在電容和絕緣電阻，可以構成電流通路，接地電流很小，不足以使保護裝置動作而切斷電源，不能確保人身安 全。而對于中性點接地的系統(tǒng)，當一相接地后接地電流較大，保護裝置會迅速動作，斷開故障點。

(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）降低電氣設備對地的絕緣水平。在中性點不接地的系統(tǒng)中，當一相接地時，將會使另兩相得對地電壓升高到線電壓。而對于中性點接地的系統(tǒng)，當一相接地時，另兩相的對地電壓只接近于相電壓，故可降低電氣設備和輸電線路的絕緣水平。

(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、保護接地保護接地常用于中性點不接地的低壓系統(tǒng)中，它的作用是：當電動機某一繞組的絕緣結構已破壞使外殼帶電時，如果未接地，人體觸及外殼，相當于單相觸電，就可能發(fā)生觸電的危險。而如果采用了保護接地，人體觸及外殼時，由于人體的電阻與接地電阻并聯(lián)，由于人體電阻；遠大于接地電阻，通過人體的電流就很小，就不會發(fā)生觸電的危險。

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、保護接零保護接零常用于中性點接地的低壓系統(tǒng)中，它的作用是：當電動機某一繞組的絕緣結構已破壞而與外殼相接時，由于采用保護接零，就形成單相短路，迅速將這一相中的熔絲熔斷，外殼便不再帶電。即使在熔絲熔斷前人體觸及外殼時，也由于人體電阻遠大于線路電阻，通過人體的電流也很微小，不會發(fā)生觸電危險。

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.

另外還需注意，發(fā)電機零線接地要考慮具體的情況，首先要確認變壓器是否有漏電保護，一般進口發(fā)電機組是零地合一的，用的時候要拆掉，否則變壓器有漏電保護的情況下很可能會跳。而國產發(fā)電機組的地線通常在地盤上，單獨接地，零線和市電的零線接在一起。相線（三相線）要用專用開關把市電和發(fā)電做互鎖控制，以免市電加在發(fā)電機組上。

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.