Help with a 3 phase star delta motor

[TF and the wire]

Not had the chance to read every reply on this but it sounds like the reason it was running slower was because in star, it only had 230v on its windings which were designed for 400v. In effect it was almost stalling. Then when the delta kicked in, it had the full 400v and ran at its designed speed.
4kW motor is well able to be run of a DOL starter. If you didn't want to get another starter you could connect it in delta and connect the 3 cables to the load side of the RUN contactor (see the diagram on a previous page). Just make sure that the overload setting is within range about 8amp.
I wouldn't bother with an invertor unless the customer wants to vary the speed.

 

[remer1957]

I think that there's a bit of inexperience here-maybe you should have told the customer that the motor was sha**ed and that you would replace the whole lot as a new installation, then at least he is bearing the cost (it is a business cost), not you wasting your time trying to get the whole story out of him. IMO there is a line which you don't want to cross, otherwise you may become a busy fool. If this happens on a few jobs at the same time you would need overloads to manage. Also, a new installation is not always more expensive-it comes with guarantees and warranties, you can be sure the whole install will do what it says on the tin and he gets peace of mind for the future. If he does go elsewhere someone else can be a busy fool.