... . Special in Middle East,south Africa,American; 3. I-O-II transferring mode with fire control function; IEC ... machanical interlock.9) the shell is made of fibreglass unsaturated polyester resin ,it has strong dielectric properties, the protection and ... shell , the shell sw itching components used fiberglass unsaturated polyester resin man ufacturi ng,with a strong dielectric properties, protection ...