Hi, where did the specs for this solenoid come from?
No way is it 3kW rated, so it must be an AC solenoid, prob 50 or 60Hz, thus 50% duty cycle.
3kW is more than a electric heater that you plug into a wall socket produces, and that coil will get that hot with DC.
I gather you want to use 30V, what do you want to actually do with the solenoid.
Sorry but it looks like a bobbin of copper wire rather than a purpose built solenoid.
Are sure its not just an inductor and nothing to do with mechanical actuation?
Because you are relying on mechanical forces operating on the individual windings when used as a solenoid, it would be wound neater and more uniform to do that job.
Tom..... 
PS yay just finished daylight saving, the forum clock is now in sync.