전기적스위치; 계전기; 셀렉터(selector); 비상보호장치(접촉케이블 h01b 7/10;  h01g 9/18; h02h; 무접점 전자장치에 의한 개폐 h03k 17/00) electric switches; relays; selectors; emergency protective devices (contact cables h01b7/10;  electrolytic self-interrupters h01g9/18;  emergency protective circuit arrangements h02h;  switching by electronic means without contact-making h03k17/00) 