What is arc suppression and harmonic suppression? Arc suppression and harmonic suppression are generally aimed at ungrounded neutral systems.
Arc suppression and harmonic suppression cabinet, also known as microcomputer arc suppression and harmonic suppression line selection and overvoltage protection device, is used in the power industry for power systems with ungrounded neutral points, neutral points grounded through arc suppression coils, or neutral points grounded through high resistance. It can limit various types of overvoltage in the system, effectively improving system operation safety and power supply reliability.
At the same time, due to the long duration of arc grounding overvoltage, the energy easily exceeds the bearing capacity of the lightning arrester, leading to the explosion of the lightning arrester. Furthermore, the high amplitude overvoltage generated by arc grounding exacerbates the cumulative damage and even breakdown of solid insulation such as cables.

In a neutral ungrounded system, when the zero sequence capacitance is too large (mainly formed by the ground capacitance of the line and cable), it increases the single-phase grounding current. When intermittent faults occur to the ground, it is not easy to extinguish the arc, causing arc grounding, overvoltage, endangering the safety of the system, and also increasing the probability of electric shock injury to the human body. Therefore, when the grounding current exceeds 10A, it is generally necessary to install arc suppression coils to compensate for the grounding current.
When there is a non-linear inductive load between phases in an ungrounded system (such as a voltage transformer), the disturbance of the system is likely to cause resonance between zero sequence capacitance and inductance. As the resonance voltage increases, the non-linear inductance will decrease and the oscillation will intensify, eventually maintaining at a high voltage level, causing a high ground overvoltage, which is also known as ferromagnetic resonance. This resonance can be eliminated or weakened by installing harmonic elimination equipment on the secondary side of the voltage transformer. Let's take a look at several common harmonic elimination schemes in the power system.
In order to take harmonic elimination measures for the distribution network, when selecting secondary harmonic elimination devices such as microcomputer harmonic elimination devices, as well as primary harmonic elimination devices such as neutral point harmonic elimination damping resistors and harmonic elimination type voltage transformers in the same distribution network, it should be determined according to the specific situation of the power grid. It is best to combine the primary harmonic elimination device with the secondary harmonic elimination device to complement each other's advantages. To ensure equipment safety, measures such as limiting intermittent arc grounding overvoltage should also be taken while taking harmonic elimination measures.