A Study on the Condition Monitoring Diagnosis of a Closed-Switchboard by Detection of Radiated Electromagnetic Waves

This thesis dealt with a basic study on the development of condition monitoring diagnostic technique for power facilities installed inside closed-switchboards. Major causes of accidents in a closed-switchboard are series arc discharge by incomplete connection and partial discharge by insulation degradation. The series arc discharge was simulated using a terminal block and an electrode system of a stainless needle-carbon rod. The corona discharge was simulated in five types of electrode system which consist of a needle and a plane electrode. The experiment was carried out in an electromagnetic shielding room, and the measurement system was composed of an Ultra log antenna of 30MHz∼2GHz and an EMI test receiver of 150kHz∼2GHz, and a spectrum analyzer. Frequency spectrum of series arc discharge was distributed in ranges of 30MHz∼200MHz for the needle-carbon rod and of 30MHz∼400MHz for the terminal block. In corona discharge, frequency spectrum existed in ranges of 30MHz∼2GHz depending on types of electrode system. The experimental results showed that frequency spectrum is different as abnormal condition varies, and the inner space of a closed-switchboard is not influenced by outer noise generated by electrical accident or broadcast wave. Consequently, it is possible to diagnose the condition of closed-switchboards by detecting radiated electromagnetic waves.제 1 장 서 론 1 제 2 장 이 론 4 2.1 폐쇄배전반 4 2.2 절연열화 9 2.3 진단기법 20 제 3 장 실험 및 방법 22 3.1 실험계 22 3.1.1 아크 발생장치 23 3.1.2 코로나 전극계 25 3.2 실험 방법 28 제 4 장 결과 및 고찰 29 4.1 아크 방전 30 4.2 코로나 방전 32 제 5 장 결 론 37 참 고 문 헌 3