I have a 15 HP motor on my Cyclone. When originally installed, it was right at full nameplate amperage with just the ductwork to and from the building (no branches installed yet). Now the amp draw has risen 3A on the middle leg compared to the other 2 legs. The starter's thermal overloads are starting to trip even on moderate loads - 3-4 gates open - a small portion of the initial test load. I have checked the starter, shutoff switch, and fuses to make sure they have good connections.
So first question - Is this a sign that the motor is going bad?
The bearings are not silent, but not too noisy.
Second question - I have heard more than one other user report motor overload problems in similar systems. Does a moderate to heavily loaded system like this wear out motors?
Third question - If you put a higher HP motor on the exact same load, will the amp draw be higher if motor efficiency is the same?
Fourth - My options seem to be to replace the motor with exact same model or one with higher efficiency and higher service factor, or replace bearings and have motor shop check out the existing motor. Or both , and keep the old motor as a spare. Which would you be inclined to do?
Thanks for any insight.