The ct.qmat team have employed the PT symmetry to still make the open circuit system with gain and loss share a large amount of features with an isolated system.

There are three major sources of fault current: an electric utility power system, a generator, and a motor. Short circuit faults are called shunt faults. An open-circuit condition is known as a series ...

BGE reviews several alternatives for a battery open-circuit monitoring device to protect from a dc supply single point of failure. The Federal Energy Regulatory Commission issued Order 867 on Jan. 23, ...

Qucs is a GPL circuit simulator. And if you want the GUI option, you might want to try out QucsStudio, which uses Qucs under the hood, and is free to use, but binary-only.