At present, it is a common phenomenon to use the neutral point of the generator to be grounded by resistance (that is, to install the neutral point grounding resistance cabinet on the neutral point of the generator) to protect the generator set. The neutral point is also called “zero point”, which refers to three-phase or Common point for star wiring in polyphase AC systems. The neutral point grounding method involves the safety, reliability and economy of the power grid, and directly affects the selection of the insulation level of the system equipment, the overvoltage level, the relay protection method, and the communication interference. It mainly plays the role of stabilizing the voltage and current.
The conditions of use of the resistance cabinet:
1. Generally used for indoor generators;
2. The altitude is not higher than 1000 meters;
3. Ambient temperature: -20°C~+70°C, relative humidity not more than 95%;
4. Used in systems with grid frequency 48~52Hz (50H system);
5. There is no flammable, explosive, corrosive gas and conductive dust in the surrounding environment.
The generator neutral point resistor cabinet is generally installed indoors, and the external dimensions of the resistor cabinet are determined according to the specific parameters of the user.
So should diesel generator sets be installed with neutral grounding resistance cabinets for protection?
Reminds the users: according to the correct operation method, the service life of the generator set can be extended, and the grounding or ungrounding of the diesel generator set should be determined by the specific conditions of the power system. The diesel generator set is only one component of the system, and the relationship with the normal mains power supply and distribution system should be considered. Therefore, the grounding problem is not isolated, it is closely related to protection, insulation, fault operation mode, etc. The requirements for the use of diesel generator sets as an emergency power supply and as a backup power supply are also different, and they need to be considered as a whole.
