Ungrounded systems as reflected in the standards

Unearthed power supplies (IT systems) are always used in situations where an initial insulation fault must not cause a protective device to respond, thereby interrupting the power supply. Classic fields of application, for example are in medically used locations, sensitive processes in the industrial sector, and feedback-controlled drives in heavy industry. New applications in electromobility and DC systems have come along as part of the paradigm shift in energy usage occurring now. This article provides an overview of the prevailing situation with respect to the standards.