The transformer neutral grounding resistance cabinet is to add a resistor between the grounding phase and the neutral point of the transformer when a single-phase grounding fault occurs, which can limit the single-phase grounding fault current.
The neutral point grounding method of the power distribution system usually has a neutral point that is not grounded, a neutral point is grounded through the resistor, and a neutral point is grounded via the arc suppression coil. Different grounding methods are used and the way of use is different. With the development of the national economy, many urban distribution networks have changed the situation of overhead lines in the past, but mainly cable lines. At the same time, some new types of equipment, such as compact closed SF6 switchgear, Cross-linked polyethylene cables and zinc oxide surge arresters have become more and more widely used, which makes some non-effective grounding methods that were originally used somewhat unsuitable. Therefore, how to effectively and economically set the neutral point grounding has become the focus of current power supply work.
At present, many neutral points in China's distribution network have adopted the operation mode of resistance grounding. After installing the neutral grounding resistance cabinet, when non-metallic grounding occurs, the current flowing through the grounding point and the neutral point is significantly lower than that of the metallic grounding due to the resistance of the grounding point. At the same time, the sound phase voltage rises. Significantly reduced, the zero sequence voltage is approximately half of the single phase metallic ground. It can be seen that the neutral point through the resistor grounding can reduce the transient over-voltage during single-phase grounding, eliminate the arc grounding over-voltage and some resonant over-voltage, and can quickly select the fault line with a simple relay protection device. Remove the fault point.