Dielectric Strength Recovery After Gas Arcs of Low-Voltage DC Hybrid Interruption

Investigating the post-arc dielectric strength recovery characteristics is essential for dc hybrid interruption, because a successful interruption in a hybrid dc switch is determined by the competition between the power system recovery voltage and post-arc dielectric strength recovery voltage. Based on a review of previous studies, related research is inadequate in the recovery of gas dielectric strength and research on the contact opening process is lacking. In order to investigate the influence of the rate of current reduction $\text{d}{i}/\text{d}{t}$ , arcing time, and electrode material on the breaking capacity of low-voltage dc hybrid switches, the dielectric strength recovery was measured after the quenching of gas arc. An experimental circuit and a pulse voltage generator were used to measure the post-arc dielectric strength recovery characteristics. The experimental results indicate that decreasing $\text{d}{i}/\text{d}{t}$ or the arcing time increases the dielectric strength recovery speed. However, there is a critical arcing time in the contact opening process that results in the fastest dielectric strength recovery speed. The optimal range of recovery time is proposed, which is an important parameter for the design of low-voltage dc hybrid switches.

I. Introduction

In recent years, continuous global energy shortages and environmental problems have received increasing attention, and many researchers around the world focused on the reduction of CO2 emission [1], [2]. Photovoltaic power generation devices, electric vehicles, and wind turbines [3] have been rapidly developed as an important part of renewable power sources, and dc grids are becoming widely used aiming to evaluate energy efficiency and cable weight. The system voltage of electric vehicle has reached 450 V [4], the dc power supply voltage of multielectric aircraft has reached 270 V [5], [6], and the new commercial buildings in Europe are supplied with a dc power of ±380 V [7]. A dc system has a high rise rate in short-circuit current and a high arc energy [8] since the dc system has low damping and large capacity. The dc switch needs to meet the following requirements: rapid commutation of the fault current, long lifetime, and reliable dielectric recovery characteristics.