1. Product Overview
In the 3～35kV power grid with non-effective grounding at the neutral point, except for the lightning overvoltage, the overvoltage caused by the single-phase intermittent arc grounding and resonance is the most frequent, and has a high amplitude and a long duration. The internal insulation of electrical equipment causes cumulative damage, causing breakdown or phase flashover at the weak point of external insulation, causing short-circuit accidents and causing explosions of zinc oxide arresters without gaps.
At present, the main measure to limit the arc grounding overvoltage is still to ground the neutral point of the grid through the arc suppression coil. However, the arc suppression coil does not limit the intermittent arc grounding overvoltage. Even due to the existence of the arc suppression coil, the arc reignition may occur at the maximum recovery voltage, so that the arc grounding overvoltage is higher. The arc suppression coil cannot compensate for the high frequency component and the active component of the ground current. The high frequency intermittent arc ground fault cannot be eliminated. When the active component is greater than a certain value, the grounding arc of the fault point cannot be self-extinguishing. The actual operating experience also proves that in the 3～35KV power grid where the neutral point is grounded by the arc suppression coil, accidents caused by arc grounding and resonance sometimes occur.
2, product features
1) It is possible to limit various types of overvoltages to lower levels, so that insulation accidents caused by overvoltages are greatly reduced.
2) The mechanism of arc suppression and limiting overvoltage is independent of the magnitude of the grid capacitor current, so its protection performance is not affected by the change of grid operation mode and grid expansion.
3) The system that originally installed the arc suppression coil according to the design specifications can no longer be installed; and its function of limiting the arc grounding overvoltage is better and more perfect than installing the arc suppression coil.
4) The probability of explosion of metal zinc oxide surge arresters (MOAs) in such power grids is greatly reduced.
5) The system does not need to be equipped with a dedicated harmonic elimination device, and the effect is better.
6) The whole device and the PT form a high-voltage switchgear, which has a simple structure, small volume, convenient installation and debugging, and wide application range.