A HFID-based online testing technique for internal pressure of vacuum breaker

The internal gas pressure of vacuum breaker (VCB) is a main influencing factor which effects on the VCB´s electric properties. The decaying gas pressure in arc chamber will not only cause the supply voltage to be beyond the VCB´s endurance, but also very difficult to cut off the fault current effectively. With the decline of the arc chamber´s vacuum degree, because of the arc quenching performance deterioration, the partial discharge phenomena will occur between the contact and arcing cover, and the discharge high-frequency impulses will be formed. By capturing these impulses, we can detect indirectly the shield potential of the arc chamber, so as to understand the arc chamber´s vacuum degree accurately. Because the non-contact electric field receiving antenna is adopted as the detecting element, so we detect the vacuum degree without cutting off the power supply, reaching the purpose of the VCB online detection.