Many users know that in order to ensure the personal safety of diesel generator operators and meet the needs of the power system, diesel generator sets have strict grounding requirements. There are three grounding methods for diesel generator sets: working grounding, protective grounding, and protective grounding. This article will explain in detail why diesel generator sets must be grounded.

1、 Work grounding refers to grounding the neutral point. Its purpose is to:

1. Reduce the electric shock voltage. For systems with ungrounded neutral points, 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 the phase voltage; For neutral grounded systems, the electric shock voltage drops to be close to or equal to the phase voltage.

2. Quickly cut off faulty equipment. For systems with ungrounded neutral points, when one phase is grounded, due to the presence of capacitance and insulation resistance between the wire and the ground, a current path can be formed. The grounding current is small enough to activate the protective device and cut off the power supply, which cannot ensure personal safety. For systems with neutral grounding, when one phase is grounded and the grounding current is high, the protective device will quickly act to disconnect the fault point.

3. Reduce the insulation level of electrical equipment to ground. In a system where the neutral point is not grounded, when one phase is grounded, the ground voltage of the other two phases will increase to the line voltage. For systems with neutral grounding, when one phase is grounded, the ground voltage of the other two phases is only close to the phase voltage, which can reduce the insulation level of electrical equipment and transmission lines.

2、 Protective grounding

The protective grounding of generator sets is commonly used in low-voltage systems with ungrounded neutral points. Its function is to prevent the risk of electric shock if the insulation structure of a certain winding of the motor is damaged and the casing is charged. If the grounding is not done and the human body touches the casing, it is equivalent to a single-phase electric shock. If protective grounding is used, when the human body touches the shell, due to the parallel connection between the human body's resistance and the grounding resistance, the human body's resistance; Far greater than the grounding resistance, the current passing through the human body is very small, so there is no risk of electric shock.

3、 Protective neutral connection

Protective neutral connection is commonly used in low-voltage systems with neutral grounding. Its function is to quickly fuse the fuse in one phase when the insulation structure of a motor winding is damaged and connected to the casing, resulting in a single-phase short circuit. The casing no longer carries electricity. Even when the human body touches the shell before the fuse melts, the current passing through the human body is very small due to the human body resistance being much greater than the line resistance, and there is no risk of electric shock.

Guangzhou Saiwei Energy Technology Co., Ltd. is a comprehensive enterprise specializing in the design, production, and installation of generators. Guangzhou Saiwei has many years of experience in engineering design and installation services. For many years, Guangzhou Saiwei has been committed to providing every customer with comprehensive products and energy solutions, including technical consulting, whole machine and generator supply, operation training, etc., with leading technology and first-class quality. The product range covers land diesel generator sets, marine generator sets, high-voltage generator sets, etc., and is widely used in industries such as power, communication, iron towers, healthcare, financial systems, data centers, etc. Welcome to inquire: 13302262088