good afternoon ,

I need a bit of a advice in correct sizing of a soft start 3RW40.

application is a large fan 45Kw , I have found that 3RW4046-1BB14 might not be suitable and it is recommended that for this application choosing a size up might be required . based on this information I have chosen 3RW4047-1BB14 but in the manual I have found that in a large fan application where fan inertia is exceeding 10 times the inertia of a motor series 3RW40 should be replaced with 3RW44.

I would like to avoid mistake due to wrong sizing and I am relying on yours opinion.

Application 

Large suction fan preferable start within 15-20 sec, motor connection delta , installation with an optional contactor 24vdc , coastal stop and protection from direct start after stop (time delay).

Kind Regards 

K.R