Hi , do i need to learn first microstation before learning openplant modeler?
No, you don't need to.
I haven't used Microstation and only used OpenPlant. But let's say - it would be much easier for new user to go from Microstation to OpenPlant, then from Civil/ACad to OpenPlant.
As I see OpenPlant: Microstation engine with additional "addons" (pipes, valves, equipment etc.). But also with also solid and surface functions.
If you will need to do projects with openBim then go straight to OpenBuild ( it's slower and has less components options - but at least it exports files to IFC) or even go to Civil/Revit..
All Bentley products comes with really basic libraries, so take in mind that you will need to make a lot of configurations and hand writing pipes, fittings etc. specifications. But for me it was the cross that we choose to carry, because microstation engine can work with really detailed object - like real models from SolidWorks (of course those equipment doesn't have "intelegence" but it works much better then in AutoCad engine)
thank you Nerijus for the advice