The SISD bushings manufactured by RITZ Instrument Transformers GmbH are insulated using the Epoxy Resin Impregnated Paper technology (ERIP) and are designed and dimensioned according to the specific electrotechnical requirements of each project. These bushings are available for indoor/indoor (SISD-II), indoor/outdoor (SISD-IO) or outdoor/outdoor (SISD-OO) applications, for voltages from 3,6 kV up to 72.5 kV and currents from 630 A up to 7000 A.
The conductor part of the bushing can be of copper or aluminum and is wrapped using a special paper type. Semiconductive capacitive grading layers are embedded during the wrapping process in order to control the electrical field. A grounding layer is also embedded across the entire length. The composite insulation is then cast in epoxy resin under vacuum.
After manufacture, each SISD bushing is routine tested according to IEC60137, this guarantees partial discharge free operation as well as the safety for human operators and the long-life span of the bushing.
All bushings are protected mechanically by high-quality shrinking sleeves which protect the insulation from humidity, dust and light knocks along the complete length of the bushings. In order to increase the creepage distance without adding additional bushing length, silicone insulator sheds are used. The SISD bushings have as standard 31mm/kV specific creepage distance, which according to IEC 60815 corresponds to a very high level of pollution.
If required, the bushings can integrate ring core current transformers also manufactured by RITZ Instrument Transformers GmbH, thus offering a complex customized solution.