Jens - MWB Hochspannungs technik GmbH F. R. Germany
Innerling - MWB Hochspannungs technik GmbH F. R. Germany

High energy discharges in conventional oil paper insulated instrument transformers lead to explosions with disastrous consequences for the other substation equipment and the environment. The use of SF 6-gas as insulating medium and a new transformer construction solves the problems and guarantees the preventation of any ccnsequential damages. Physics, construction and function of SF 6-insulated instrument transformers are described. Results from field experiences over a a period of more than 10 years show the reliability of this new safety concept.