From FreeCAD Documentation
- After adding an Elmer solver as described here, select it in the tree view.
- Either use the toolbar button or the menu Solve → Electromagnetic Equations → Electricforce equation.
- Now either use the toolbar button or the menu Solve → Electromagnetic Equations → Electrostatic equation. This is important because the electricforce equation needs the potential field calculated by the Electrostatic equation.
- Change the equation's solver settings or the general solver settings if necessary.