Hi.
My air compressor is supposed to run from a source of somewhere between 1.5 HP and 2.5 HP electric motor (230V - 60 Hz - 3450 rpm)
A 5 HP motor (230V - 60 Hz - 3450 rpm) is available to buy instead. If I install such 5 HP, will it just consume the needed current the compressor demands, or the consumption will be higher ? Will instead a 3 HP motor be a better choice, and why ? All motors cost the same. Electrical supply circuit and breaker is enough for any.

 

The off load current of a 5HP over a 1.5 to 2.5 motor is going to be a little higher. And just a little over-kill.
Unless the compressor is in continuous use, you most likely will not notice that much difference in consumption, do you have the circuit capable of supplying it?
Max.