What pulley do I need for my new air compressor motor

Word of caution, as pointed out by John York, is to derate your motor. I put a HF 5 hp head on a compressor years ago, and ordered pulleys to make it run at its rated speed on the gnat's ass (it was around 3.25:1 ratio). It was just enough to ensure the motor cools for half the duty cycle. The little 5hp rated Leeson hit thermal overload constantly. So either the pump was underrated, or the motor is overrated, or a combination of the two. In retrospect, 900 rpm would have been better than the "rated" 1150 rpm on the data plate. Trust USA data plates, doubt Asian ones, I guess...
 
That is why one must review all of the data sheets.

Motors can be rated as "compressor duty"

Compressors can pump specified pressure, but a slight change in RPM can make a huge change in motor requirements.

If the overload is tripping, the pressure is too high for the motor capacity.

Either slow down the compressor or reduce the pressure.

Even commercial units can trip.

Our unit is maybe 14 years old with intermittent weekend use.

The overload recently started to trip.

What is up?

The cutout pressure was 180 ish, and it is very cold being winter.

Cold air is more dense, so more mass of air is in the same volume compared to summer.

Pressure switch just needed minor adjustment to return to 175, set it to maybe 160 to reduce operating cost, 7.5 hp pulls some amps.


Sent from my SM-G781V using Tapatalk
 
You must log in or register to reply here.
Back
Top