Reasons for Diesel Generator Grounding

Diesel generators can have their service life extended by following correct operating procedures. Guangxi Dingbo recommends that customers refer to the generator set operation manual for implementation. What is the reason for grounding diesel generators during use? To ensure personal safety and the operational needs of the power system, there are strict requirements for generator set grounding. There are three types of generator set grounding methods: working grounding, protective grounding, and protective neutral grounding.

1.Working Grounding

Working grounding refers to grounding the neutral point. Its purposes are as follows:

1.1 Reduce electric shock voltage. In a generator set system where the neutral point is not grounded, when one phase is grounded, if a person comes into contact with one of the other two phases, the electric shock voltage will be more than 1.7 times the phase voltage. However, in a system with a grounded neutral point, the electric shock voltage is reduced to approximately or equal to the phase voltage.

1.2 Quickly disconnect faulty equipment. In a system with an ungrounded neutral point, when one phase is grounded, the capacitance and insulation resistance between the conductor and the ground can form a current path, resulting in a small grounding current that is insufficient to cause the protection device to operate and cut off the power supply, thus failing to ensure personal safety. In contrast, in a neutral grounded system, when one phase is grounded, the grounding current is relatively large, and the protection device will act quickly to disconnect the fault point.

1.3 Reduce the insulation level of electrical equipment to the ground. In a system with an ungrounded neutral point, when one phase is grounded, the ground voltage of the other two phases will rise to the line voltage. In a system with a grounded neutral point, when one phase is grounded, the ground voltage of the other two phases is only close to the phase voltage, thus reducing the insulation level of electrical equipment and transmission lines.

2.Protective Grounding

Protective grounding of generator sets is commonly used in low-voltage systems with ungrounded neutral points. Its function is: when the insulation structure of one winding of the motor is damaged, causing the shell, to become live, if it is not grounded, a person touching the shell is equivalent to a single-phase electric shock, which may lead to the danger of electric shock. However, if protective grounding is adopted, when a person touches the shell, since the human body resistance is in parallel with the grounding resistance, and the human body resistance is much larger than the grounding resistance, the current passing through the human body will be very small, and there will be no danger of electric shock.

3.Protective Neutral Grounding

Protective neutral grounding is commonly used in low-voltage systems with grounded neutral points. Its function is: when the insulation structure of one winding of the motor is damaged and connected to the shell,, the adoption of protective neutral grounding forms a single-phase short circuit, and the current can quickly blow the fuse in this phase, so that the shell, is no longer live. Even if a person touches the shell, before the fuse blows, the human body resistance is much larger than the line resistance, and the current passing through the human body is very small, so there will be no danger of electric shock.

Guangxi Dingbo Generator Set Manufacturing Co.,Ltd. was founded in 1974 and is one of the earliest manufacturers of generators and diesel generator sets in China. If you want get more information, please feel free to send email to [email protected] we will pay highly attention on your question.