Since ARTEMiS version 7.2, the SSN solver sets all initial states to zero, including transformer magnetization current and fluxes. This overrides all initial conditions that are sometimes set directly inside the masks of many SPS transformer models.
A common usage involving transformer model initial conditions is the study of inrush current caused by residual flux. With all initial states set to 0, users now must use methods that are closer to real-life methods. For example, to study the inrush currents of a saturable transformer, the user should now make 2 maneuvers with the transformer feeding breaker:
- Open the breaker at a prescribed angle so that the transformer flux is left constant at the desired value.
- Reclose the breaker and observe the inrush currents, if any.
Inrush current studies are often combined with Monte Carlo simulation to determine the statistical distribution of the inrush current. Monte-Carlo simulations can be done efficiently using SSN in the eMEGAsim simulator.