First you have to ask, what is a motor starter?
In a strict code sense you just need to satisfy all the requirements of 430. A packaged motor starter is the easiest way to do it.
When the overload protection is internal you are basically just looking for a way to start and stop the motor. At that point the size of the motor is probably the determining factor.
The magnetic starter (contactor) allows a fairly small switch to control a large motor. There are drum switches that will run motors up into the 10HP range tho.
I think most fractional HP motors are going to be controlled by a switch with internal O/L protection unless they are part of a larger machine that controls them with a relay.
